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Chao, L. L. & Knight, R. T. Human prefrontal lesions increase distractibility to irrelevant sensory inputs. Neuroreport 6, 1605-1610
Abstract
Neurological patients with focal lesions in either the dorsolateral prefrontal cortex, temporal-parietal junction or the posterior hippocampus, and control subjects, were tested on a task requiring short-term retention of environmental sounds. Subjects had to indicate whether initial and subsequent test sounds were identical in two conditions. The initial and test sounds were separated by either a silent period varying from 4 to 12.6 s (no-distractor condition) or a series of irrelevant tones (distractor condition). Prefrontal patients were significantly impaired by distractors at all delays, hippocampal patients were impaired only at longer delays, while temporal-parietal patients performed similar to controls. The findings suggest that dorsolateral prefrontal cortex is crucial for gating of distracting information during delay tasks.
... The definition of interruption is closely related to distraction, which is researched in the field of road safety (see [95] for a review). The difference between distractions and interruptions is that the former are encountered stimuli intended to be ignored [25] and filtered out by a top-down suppression of signals from the prefrontal cortex [20,21]. The latter are stimuli that represent aspects of a secondary task, resulting in a reallocation of cognitive resources [25]. ...
Today's information and communication devices provide always-on connectivity, instant access to an endless repository of information, and represent the most direct point of contact to almost any person in the world. Despite these advantages, devices such as smartphones or personal computers lead to the phenomenon of attention fragmentation, continuously interrupting individuals' activities and tasks with notifications. Attention management systems aim to provide active support in such scenarios, managing interruptions, for example, by postponing notifications to opportune moments for information delivery. In this article, we review attention management system research with a particular focus on ubiquitous computing environments. We first examine cognitive theories of attention and extract guidelines for practical attention management systems. Mathematical models of human attention are at the core of these systems, and in this article, we review sensing and machine learning techniques that make such models possible. We then discuss design challenges towards the implementation of such systems, and finally, we investigate future directions in this area, paving the way for new approaches and systems supporting users in their attention management.
... Therefore, the PFC plays important roles in controlling human behavior, including top-down regulation of behavior, thought and emotion, generating the mental representations needed for flexible, and goal-directed behavior. Previous research has demonstrated that impairment of the PFC can affect attentional focus (Chao and Knight, 1995;Wilkins et al., 1987), as well as impulse control, potentially leading to reckless behavior (Aron, 2011). ...
... At early stages of sensory processing, one of the many functional roles of the prefrontal cortex is the gating of afferent sensory information (Yamaguchi & Knight, 1990). The dorsolateral prefrontal cortex (DLPFC) plays a crucial role in sensory gating, the goal-directed control of attention, and inhibition of irrelevant information (Chao & Knight, 1995). The DLPFC was previously found to be hypoactivated in the left (Bishop, 2009) and hyperactivated in the right hemisphere (Basten et al., 2011(Basten et al., , 2012Forster et al., 2015) during cognitive tasks in healthy, highly anxious individuals. ...
Evidence suggests that trait anxiety relates to cognitive processing and behavior. However, the relationships between trait anxiety and sensory processing, goal‐directed performance and sensorimotor function are unclear, particularly in a multimodal context. This study used electroencephalography to evaluate whether trait anxiety influenced visual and tactile event‐related potentials (ERPs), as well as behavioral distractor cost, in a bimodal sensorimotor task. Twenty‐nine healthy young adults completed the State–Trait Anxiety Inventory. Participants were directed to focus on either tactile or visual stimuli while disregarding the other modality, responding to target stimulus amplitude with a proportional grip. Previous research suggests that somatosensory N70 and visual P2 ERPs serve as markers of attentional relevance, with attention also impacting the visual P3 ERP. It was hypothesized that trait anxiety would modulate the ERPs susceptible to attentional modulation (tactile N70, visual P2 and P3) and not affect behavioral performance. Trait anxiety showed a large, significant interaction with attention for visual P3 latency in response to unimodal visual stimuli, with a positive relationship between P3 latencies and trait anxiety when attending toward the stimulus and negative when attending away. A large, positive main effect of trait anxiety on visual N1 amplitude for bimodal stimuli was also detected. As predicted, trait anxiety related to ERPs but not behavioral distractor cost. These findings suggest that trait anxiety modulates visual but not somatosensory processing correlates based on attention. The absence of overt behavioral performance effects suggests compensatory mechanisms may offset underlying differences in sensory processing.
... The process of change detection ref lected by the MMN is known to take place in the auditory cortex, with contributions from frontal regions (Näätänen and Alho 1995;Opitz et al. 2002;Molholm et al. 2005;Näätänen et al. 2007). The frontal cortices play an important role in selective attention and orienting (Knight et al. 1981;Chao and Knight 1995), which is why the MMN is thought to ref lect an "attention switch" toward deviant sounds (Giard et al. 1990;Näätänen and Alho 1995). In addition, the topdown modulation of visual processing is widely thought to be mediated by frontal-to-visual cortex projections (Desimone and Duncan 1995;Kastner and Ungerleider 2000;Miller and Cohen 2001;Knudsen 2007 Goddard et al. 2022). ...
While the auditory and visual systems each provide distinct information to our brain, they also work together to process and prioritize input to address ever-changing conditions. Previous studies highlighted the trade-off between auditory change detection and visual selective attention, however, the relationship between them is still unclear. Here, we recorded electroencephalography signals from 106 healthy adults in three experiments. Our findings revealed a positive correlation at the population level between the amplitudes of ERP indices associated with auditory change detection (MMN) and visual selective attention (N2pc) when elicited in separate tasks. This correlation persisted even when participants performed a visual task while disregarding simultaneous auditory stimuli. Interestingly, as visual attention demand increased, participants whose N2pc amplitude increased the most exhibited the largest reduction in MMN, suggesting a within-subject trade-off between the two processes. Taken together, our results suggest an intimate relationship and potential shared mechanism between auditory change detection and visual selective attention. We liken this to a total capacity limit that varies between individuals, which could drive correlated individual differences in auditory change detection and visual selective attention, and also within-subject competition between the two, with task-based modulation of visual attention causing within-participant decrease in auditory change detection sensitivity.
... The DLPFC is involved in attentional and executive functions. It is important to select and direct attention to relevant information from various sensory sources, as well as from working memory, filtering nonrelevant stimuli and focusing attention [28]. The right DLPFC is particularly involved in exploratory attention [29]. ...
Background
Involuntary limb activation using functional electrical stimulation (FES) can improve unilateral spatial neglect. However, the impact of FES on brain activity related to spatial attention remains unclear. Thus, in this study, we aimed to examine the effects of FES on spatial attention.
Methodology
In this interventional study, 13 healthy right-handed participants were asked to perform the Posner task for six minutes both before and after either FES or sham stimulation during each set, resulting in a total of two sets. FES was applied to the left forearm extensor muscles, with a frequency of 25 Hz, a pulse width of 100 μs, and the intensity adjusted to reach the motor threshold. Both the energization and pause times were set to five seconds. The Posner task was used to measure reaction time to a target appearing on a computer screen. Brain activity, indicated by oxygenated hemoglobin values, was measured using near-infrared spectroscopy with 24 probes according to the International 10-20 system method.
Results
In the left hemisphere, oxygenated hemoglobin values in the premotor and supplementary motor areas, primary somatosensory cortex, and somatosensory association areas were significantly higher after FES than after sham stimulation. In the right hemisphere, oxygenated hemoglobin values were significantly increased in the premotor, primary, and supplementary motor areas; in the supramarginal gyrus; and in the somatosensory association areas after FES. Reaction times in the Posner task did not differ significantly between the FES and sham conditions.
Conclusions
Collectively, these results suggest that FES of the upper limbs can activate the ventral pathway of the visual attention network and improve stimulus-driven attention. Activation of stimulus-driven attentional function could potentially contribute to symptom improvement in patients with unilateral spatial neglect.
... From the behavioral perspective, early studies showed that prefrontal lesions in humans led to the inability to override prepotent responses, which manifested as an impairment in the organization of behavior (Bechara et al., 1994;Damasio, 2006). Detailed behavioral analysis have revealed that prefrontal lesions in humans led to impairments in several executive functions that support cognitive control, as working memory, setting, sustained attention, inference control, decision making, inhibitory control, planning, and strategy implementation (Milner, 1963;Eslinger and Damasio, 1985;Chao and Knight, 1995;Bechara et al., 1998;Burgess, 2000). Importantly, studies developed by Milner (1965) showed that prefrontal lesioned patients showed deficits in spatial mazes, which appeared to be non-spatial in nature but had deficits in the correct strategy to solve the mazes, showing perseverative and impulsive behaviors. ...
Cognitive control of behavior is crucial for well-being, as allows subject to adapt to changing environments in a goal-directed way. Changes in cognitive control of behavior is observed during cognitive decline in elderly and in pathological mental conditions. Therefore, the recovery of cognitive control may provide a reliable preventive and therapeutic strategy. However, its neural basis is not completely understood. Cognitive control is supported by the prefrontal cortex, structure that integrates relevant information for the appropriate organization of behavior. At neurophysiological level, it is suggested that cognitive control is supported by local and large-scale synchronization of oscillatory activity patterns and neural spiking activity between the prefrontal cortex and distributed neural networks. In this review, we focus mainly on rodent models approaching the neuronal origin of these prefrontal patterns, and the cognitive and behavioral relevance of its coordination with distributed brain systems. We also examine the relationship between cognitive control and neural activity patterns in the prefrontal cortex, and its role in normal cognitive decline and pathological mental conditions. Finally, based on these body of evidence, we propose a common mechanism that may underlie the impaired cognitive control of behavior.
... berg, & Weinberger, 1993, for review) but normally spared in MT amnesia (e.g., Chao & Knight, 1995;Drachman & Arbit, 1966;Hopkins, Kesner, & Goldstein, 1995;Janowsky, Shimamura, Kritchevsky, & Squire, 1989;Shoqeirat, Mayes, MacDonald, Meudell, & Pickering, 1990). In one particularly telling study, participants with frontal lobe damage (an etiology usually agreed to cause attentional impairments) were impaired at an extradimensional shift, which required shifting attention to a previously irrelevant stimulus dimension, whereas participants with combined lesion to amygdala and hippocampus were unimpaired in their ability to perform the shift (Owen, Roberts, Polkey, Sahakian, & Robbins, 1991). ...
Damage to the hippocampus and medial temporal (MT) structures can lead to anterograde amnesia and may also impair latent learning, in which prior exposure to cues affects their subsequent associability. Normally, latent learning may reflect both representational and attentional mechanisms. Prior work has suggested that individuals with MT amnesia have specific deficits in representational processing; thus, latent learning that invokes primarily representational mechanisms might be especially impaired in MT amnesia. The current results provide preliminary confirmation of this prediction. In Experiment 1, a latent learning paradigm expected to invoke representational mechanisms was impaired in individuals with MT amnesia, whereas in Experiment 2, a paradigm expected to invoke other attentional mechanisms was spared in individuals with MT amnesia. This suggests the representational and attentional components of latent learning are dissociable and differentially affected in anterograde amnesia.
... Dogs with medial temporal lobe lesions can retain sound identities for over a minute (Kowalska et al., 2001), although their memory for tone locations over a 10-s delay is impaired (Kowalska, 1999). Human patients with hippocampal damage can struggle to hold sounds in mind for several seconds, at least if the material cannot be rehearsed sub-vocally (Cave and Squire, 1992;Chao and Knight, 1995;Keane et al., 1995;Milner, 1972;Milner and Teuber, 1968;Penfield and Milner, 1958;Squire et al., 2001;Stefanacci et al., 2000;Wickelgren, 1968). It seems that the criticality of the hippocampus depends on species and the auditory feature to be maintained (see Supplementary Tables H, I). ...
The hippocampus has a well-established role in spatial and episodic memory but a broader function has been proposed including aspects of perception and relational processing. Neural bases of sound analysis have been described in the pathway to auditory cortex, but wider networks supporting auditory cognition are still being established. We review what is known about the role of the hippocampus in processing auditory information, and how the hippocampus itself is shaped by sound. In examining imaging, recording, and lesion studies in species from rodents to humans, we uncover a hierarchy of hippocampal responses to sound including during passive exposure, active listening, and the learning of associations between sounds and other stimuli. We describe how the hippocampus' connectivity and computational architecture allow it to track and manipulate auditory information – whether in the form of speech, music, or environmental, emotional, or phantom sounds. Functional and structural correlates of auditory experience are also identified. The extent of auditory-hippocampal interactions is consistent with the view that the hippocampus makes broad contributions to perception and cognition, beyond spatial and episodic memory. More deeply understanding these interactions may unlock applications including entraining hippocampal rhythms to support cognition, and intervening in links between hearing loss and dementia.
Schizophrenia is a severe mental disorder and a leading cause of global disability. Increasing evidence ties impairments in both auditory and visual perceptual processing to impaired functional outcomes. In the auditory system, deficits are observed in the ability to process changes in tonality, leading to deficits in the detection of nonverbal aspects of auditory communication, including emotion and sarcasm. In the auditory sytem, these deficits are indexed by impaired generation of mismatch negativity (MMN), which has become a widely utilized index of auditory perceptual dysfunction. In the visual system, deficits are especially observed in functions related to the magnocellular visual pathway, which projects preferentially to the dorsal visual stream. Dorsal stream dysfunction, in turn, contributes to impairments in processes such as fragmented object recognition, face emotion recognition, and social cognition. Indices of visual perceptual dysfunction include visual P1 responses to magnocellular-biased stimuli, as well as fMRI activation levels within the dorsal and ventral streams. Perceptual level deficits are tied most directly to impaired function of N-methyl-D-aspartate glutamate receptors (NMDAR) and thus may serve both as pathophysiologically based nosological biomarkers and as targets for neuromodulatory and pharmacological treatment development.
The detection of temporally unpredictable visual targets depends on the preceding phase of alpha oscillations (∼7–12 Hz). In audition, however, such an effect seemed to be absent. Due to the transient nature of its input, the auditory system might be particularly vulnerable to information loss that occurs if relevant information coincides with the low-excitability phase of the oscillation. We therefore hypothesized that effects of oscillatory phase in audition will be restored if auditory events are made task irrelevant and information loss can be tolerated. To this end, we collected electroencephalography (EEG) data from 29 human participants (21F) while they detected pure tones at one sound frequency and ignored others. Confirming our hypothesis, we found that the neural response to task-irrelevant but not to task-relevant tones depends on the prestimulus phase of neural oscillations. Alpha oscillations modulated early stages of stimulus processing, whereas theta oscillations (∼3–7 Hz) affected later components, possibly related to distractor inhibition. We also found evidence that alpha oscillations alternate between sound frequencies during divided attention. Together, our results suggest that the efficacy of auditory oscillations depends on the context they operate in and demonstrate how they can be employed in a system that heavily relies on information unfolding over time.
The recent publications of the inter-areal connectomes for mouse, marmoset, and macaque cortex have allowed deeper comparisons across rodent vs. primate cortical organization. In general, these show that the mouse has very widespread, “all-to-all” inter-areal connectivity (i.e. a “highly dense” connectome in a graph theoretical framework), while primates have a more modular organization. In this review, we highlight the relevance of these differences to function, including the example of primary visual cortex (V1) which, in the mouse, is interconnected with all other areas, therefore including other primary sensory and frontal areas. We argue that this dense inter-areal connectivity benefits multimodal associations, at the cost of reduced functional segregation. Conversely, primates have expanded cortices with a modular connectivity structure, where V1 is almost exclusively interconnected with other visual cortices, themselves organized in relatively segregated streams, and hierarchically higher cortical areas such as prefrontal cortex provide top–down regulation for specifying precise information for working memory storage and manipulation. Increased complexity in cytoarchitecture, connectivity, dendritic spine density, and receptor expression additionally reveal a sharper hierarchical organization in primate cortex. Together, we argue that these primate specializations permit separable deconstruction and selective reconstruction of representations, which is essential to higher cognition.
A despeito da educação formal existir há milênios e a psicologia contribuir com a compreensão da aprendizagem há mais de cem anos, técnicas eficazes de aprendizagem continuam ausentes do repertório de estratégias dos estudantes. Este trabalho teórico foca em insights da neurociência para a aprendizagem de estudantes e examina a efetividade das estratégias de estudo comumente empregadas. Um achado fundamental é que as memórias tendem ao esquecimento a menos que as emoções sejam engajadas no momento da aquisição da informação ou que ocorra uma repetição explícita do processo de aprendizagem. Além disso, prestar atenção integral ao conteúdo desejado é fundamental para otimizar a formação de traços de memória efetivos. Dessa forma, não é surpreendente que técnicas com baixa relevância para os mecanismos de atenção ou com interação limitada com as informações – como grifar textos, fazer uma leitura simples, usar palavras-chave ou imagens mentais e até mesmo fazer resumos – tenham eficácia baixa. Por outro lado, envolver-se em exercícios de resolução de problemas e estabelecer uma rotina de estudos que distribui e promove acessos espaçados à informação, engaja aspectos fundamentais dos circuitos de atenção e facilita a formação de traços de memória robustos, o que maximiza a probabilidade de aprendizagem efetiva. Por fim, direções para pesquisas futuras são apresentadas, além de uma estratégia menos conhecida, mas com potencial para promover repetição e raciocínio crítico sobre os conteúdos, a aprendizagem por meio do ensino, incluindo o método de aprendizagem Feynman.
Event-related potentials (ERPs) represent the cortical processing of sensory, motor or cognitive functions invoked by particular events or stimuli. A current theory posits that the catecholaminergic neurotransmitters dopamine (DA) and norepinephrine (NE) modulate a number of endogenous ERPs during various cognitive processes. This manuscript aims to evaluate a leading neurotransmitter hypothesis with a systematic overview and meta-analysis of pharmacologic DA and NE manipulation of specific ERPs in healthy subjects during executive function. Specifically, the frontally-distributed P3a, N2, and Ne/ERN (or error-related negativity) are supposedly modulated primarily by DA, whereas the parietally-distributed P3b is thought to be modulated by NE. Based on preceding research, we refer to this distinction between frontally-distributed DA-sensitive and parietally-distributed NE-sensitive ERP components as the Extended Neurobiological Polich (ENP) hypothesis. Our systematic review and meta-analysis indicate that this distinction is too simplistic and many factors interact with DA and NE to influence these specific ERPs. These may include genetic factors, the specific cognitive processes engaged, or elements of study design, i.e. session or sequence effects or data-analysis strategies.
Human environments comprise various sources of distraction, which often occur unexpectedly in time. The proneness to distraction (i.e., distractibility) is posited to be independent of attentional sampling of targets, but its temporal dynamics and neurobiological basis are largely unknown. Brain oscillations in the theta band (3 - 8Hz) have been associated with fluctuating neural excitability, which is hypothesised here to explain rhythmic modulation of distractibility. In a pitch discrimination task (N = 30) with unexpected auditory distractors, we show that distractor-evoked neural responses in the electroencephalogram and perceptual susceptibility to distraction were co-modulated and cycled approximately 3 - 5 times per second. Pre-distractor neural phase in left inferior frontal and insular cortex regions explained fluctuating distractibility. Thus, human distractibility is not constant but fluctuates on a subsecond timescale. Furthermore, slow neural oscillations subserve the behavioural consequences of a hitherto largely unexplained but ever-increasing phenomenon in modern environments - distraction by unexpected sound.
Although the precise mechanisms and pathways of schizophrenia remain something of a mystery, there is little dispute that cognitive deficits present as some of the clearest and most debilitating symptoms of the disease. This book describes the characteristics of cognitive deficits in schizophrenia, functional implications, the course of impairments, the genetic and biological contributions and reviews management options, including neuropsychological, psychological and pharmacological techniques. Chapters are written by leading experts in the field, in an accessible and highly informative style, ensuring the content is clinically relevant. State-of-the-art information about new developments in the treatment of related features of the illness, such as disability, is provided. The wide ranging focus of this volume will appeal to clinicians and academic researchers working with patients impaired by severe mental illness.
Although the precise mechanisms and pathways of schizophrenia remain something of a mystery, there is little dispute that cognitive deficits present as some of the clearest and most debilitating symptoms of the disease. This book describes the characteristics of cognitive deficits in schizophrenia, functional implications, the course of impairments, the genetic and biological contributions and reviews management options, including neuropsychological, psychological and pharmacological techniques. Chapters are written by leading experts in the field, in an accessible and highly informative style, ensuring the content is clinically relevant. State-of-the-art information about new developments in the treatment of related features of the illness, such as disability, is provided. The wide ranging focus of this volume will appeal to clinicians and academic researchers working with patients impaired by severe mental illness.
Although the precise mechanisms and pathways of schizophrenia remain something of a mystery, there is little dispute that cognitive deficits present as some of the clearest and most debilitating symptoms of the disease. This book describes the characteristics of cognitive deficits in schizophrenia, functional implications, the course of impairments, the genetic and biological contributions and reviews management options, including neuropsychological, psychological and pharmacological techniques. Chapters are written by leading experts in the field, in an accessible and highly informative style, ensuring the content is clinically relevant. State-of-the-art information about new developments in the treatment of related features of the illness, such as disability, is provided. The wide ranging focus of this volume will appeal to clinicians and academic researchers working with patients impaired by severe mental illness.
Although the precise mechanisms and pathways of schizophrenia remain something of a mystery, there is little dispute that cognitive deficits present as some of the clearest and most debilitating symptoms of the disease. This book describes the characteristics of cognitive deficits in schizophrenia, functional implications, the course of impairments, the genetic and biological contributions and reviews management options, including neuropsychological, psychological and pharmacological techniques. Chapters are written by leading experts in the field, in an accessible and highly informative style, ensuring the content is clinically relevant. State-of-the-art information about new developments in the treatment of related features of the illness, such as disability, is provided. The wide ranging focus of this volume will appeal to clinicians and academic researchers working with patients impaired by severe mental illness.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
Although the precise mechanisms and pathways of schizophrenia remain something of a mystery, there is little dispute that cognitive deficits present as some of the clearest and most debilitating symptoms of the disease. This book describes the characteristics of cognitive deficits in schizophrenia, functional implications, the course of impairments, the genetic and biological contributions and reviews management options, including neuropsychological, psychological and pharmacological techniques. Chapters are written by leading experts in the field, in an accessible and highly informative style, ensuring the content is clinically relevant. State-of-the-art information about new developments in the treatment of related features of the illness, such as disability, is provided. The wide ranging focus of this volume will appeal to clinicians and academic researchers working with patients impaired by severe mental illness.
Although the precise mechanisms and pathways of schizophrenia remain something of a mystery, there is little dispute that cognitive deficits present as some of the clearest and most debilitating symptoms of the disease. This book describes the characteristics of cognitive deficits in schizophrenia, functional implications, the course of impairments, the genetic and biological contributions and reviews management options, including neuropsychological, psychological and pharmacological techniques. Chapters are written by leading experts in the field, in an accessible and highly informative style, ensuring the content is clinically relevant. State-of-the-art information about new developments in the treatment of related features of the illness, such as disability, is provided. The wide ranging focus of this volume will appeal to clinicians and academic researchers working with patients impaired by severe mental illness.
Although the precise mechanisms and pathways of schizophrenia remain something of a mystery, there is little dispute that cognitive deficits present as some of the clearest and most debilitating symptoms of the disease. This book describes the characteristics of cognitive deficits in schizophrenia, functional implications, the course of impairments, the genetic and biological contributions and reviews management options, including neuropsychological, psychological and pharmacological techniques. Chapters are written by leading experts in the field, in an accessible and highly informative style, ensuring the content is clinically relevant. State-of-the-art information about new developments in the treatment of related features of the illness, such as disability, is provided. The wide ranging focus of this volume will appeal to clinicians and academic researchers working with patients impaired by severe mental illness.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
In two freestanding volumes, Textbook of Neural Repair and Rehabilitation provides comprehensive coverage of the science and practice of neurological rehabilitation. Revised throughout, bringing the book fully up to date, this volume, Medical Neurorehabilitation, can stand alone as a clinical handbook for neurorehabilitation. It covers the practical applications of the basic science principles presented in Volume 1, provides authoritative guidelines on the management of disabling symptoms, and describes comprehensive rehabilitation approaches for the major categories of disabling neurological disorders. New chapters have been added covering genetics in neurorehabilitation, the rehabilitation team and the economics of neurological rehabilitation, and brain stimulation, along with numerous others. Emphasizing the integration of basic and clinical knowledge, this book and its companion are edited and written by leading international authorities. Together they are an essential resource for neuroscientists and provide a foundation of the work of clinical neurorehabilitation professionals.
Monkeys that were trained to perform auditory and visual short-term memory tasks (delayed matching-to-sample) received lesions
of the auditory association cortex in the superior temporal gyrus. Although visual memory was completely unaffected by the
lesions, auditory memory was severely impaired. Despite this impairment, all monkeys could discriminate sounds closer in frequency
than those used in the auditory memory task. This result suggests that the superior temporal cortex plays a role in auditory
processing and retention similar to the role the inferior temporal cortex plays in visual processing and retention.
Monkeys with conjoint bilateral lesions of the hippocampus and amygdala were impaired on four different tests of memory (delayed retention of object discriminations, concurrent discrimination, delayed response, and delayed nonmatching to sample). Because tests involving delays and distractions are known to be especially sensitive to human amnesia, in three of the tasks relatively long delay intervals between training and test trials were used, and in two tasks distraction was introduced during the delay intervals. The severity of the impairment increased with the length of the delay, and distraction markedly increased the memory impairment. For one task given on two occasions (delayed nonmatching to sample), the severity of the impairment was unchanged over a period of 1.5 years. Taken together with previous findings that skill learning is unimpaired in the same operated monkeys, the results of the present study strengthen the conclusion that monkeys with medial temporal lesions constitute an animal model of human amnesia. In addition, the four tasks used here appear to constitute a sensitive and appropriate battery that could be used in other studies of the neuroanatomy of memory functions in the monkey.
Investigated the orienting response to novel stimuli in 8 normal albino rats and 16 rats with either bilateral hippocampal lesions or bilateral lesions of the neocortex overlying the hippocampus. Several different experimental situations were used. The results show that, while there is no impairment in the orienting response itself as a function of either brain lesion, the level of orienting in the hippocampally lesioned rats was severely reduced only when the novel stimulus followed another stimulus and a shift of attention was necessary for normal orienting to the novel stimulus. These results, together with earlier reports, mean that the hippocampus is importantly involved in those selective attentional processes in the rat indexed by the orienting response, depending on reciprocal neural connections between the brain stem reticular formation and the hippocampus. (21 ref.)
Although it is frequently stated that the frontal lobes play a significant role in memory function, research proof has been ambiguous at best. This problem was addressed by administering a variety of memory tests to 16 schizophrenic patients who had undergone prefrontal leucotomy approximately 25 years earlier. The 16 were divided into three groups on the basis of recovery after surgery. Two comparison groups were established to control for psychiatric symptomatology, years of institutionalization, age, and years of education. The results demonstrate that large bilateral orbitofrontal lesions may not result in amnesia; in fact, the nonoperated schizophrenic control group performed the most poorly. Proactive interference was demonstrated, however, resulting in significant impairment for all patients with prefrontal lobe damage despite normal scores on commonly used memory tests. Ability to maintain consistent and directed attention and to overcome interference is proposed as a role of the frontal lobes in memory function.
Medial septal lesions (MSL) abolished hippocampal theta activity and attenuated the overall hippocampal potential level, while frontal cortical lesions (FCL) had no effect on theta rhythm. A decrease in the overall potential level was observed only in some FCL rats. Although spontaneous behavioral patterns, including drinking, face-washing, searching, body movements, awake-and-resting, and slow-wave sleep, were not altered either by MSL or FCL during the 15 min observation, orienting responses to tones, especially searching-type, were reduced during drinking in MSL rats, while no such reductions were observed in FCL and no-lesion control rats. Auditory evoked potentials were not changed either by MSL or FCL. Spontaneous behavioral patterns were not different in FCL rats whether or not the overall hippocampal potential level was decreased.
Middle-latency auditory evoked potentials (MAEPs) were recorded in controls and patients with focal lesions in dorsalateral prefrontal cortex. Unilateral prefrontal lesions increased the amplitude of the Pa component of the MAEP beginning at 25–35 ms poststimulus. The data suggest that prefrontal cortex exerts early inhibitory modulation of input to primary auditory cortex in humans.
Four monkeys with dorsolateral frontal ablations and 3 unoperated controls were run on discrimination problems which sequentially presented both relevant and irrelevant visual stimuli prior to the opportunity for a choice response. As previously reported, monkeys with undamaged brains performed significantly better on those problems presenting relevant information first, being unaffected by later occurring irrelevant stimuli. Contrary to the behavior of the normal monkeys, monkeys with lesions of the dorsolateral frontal cortex were severely impaired when irrelevant stimuli were presented after the relevant stimuli had been processed, but before the opportunity to respond had occurred. In other words, the frontal monkeys performed just the opposite of the normals in these procedures, even though the relevant and irrelevant stimuli were manipulated within the usual temporal definitions of the two-choice discrimination trial. These data demonstrate that the presentation of irrelevant stimuli before the choice response can significantly impair frontally decorticated monkeys and that this impairment does not require the use of a long temporal delay preceding the opportunity to respond. For this reason the data were interpreted as rather direct support of the interference hypothesis of frontal dysfunction. On the basis of these and other data discussed, it was concluded that one function of the dorsolated frontal cortex involves the suppression of interfering stimulus events interposed between the information necessary to guide behavior and the behavior itself.
In order to investigate the neural mechanisms underlying short-term memory for auditory information, 71 patients who had undergone focal excision from the left or right temporal or right frontal or fronto-temporal area for the relief of intractable epilepsy were tested, together with 18 normal control subjects, on a task requiring short-term retention of tonal pitch. In the control condition, a target tone was presented, followed 1650 ms later by a comparison tone, and subjects determined whether the two had the same pitch or not. In the interference condition a series of interpolated tones was presented between target and comparison tone. Results indicated that there was no significant impairment in any patient group on the control task. In the interference task there was a significant deficit in retention of tonal information in the patients with right temporal-lobe damage, as well as in those with lesions in the right frontal lobe, and in the right frontal and temporal area. Patients with left temporal-lobe excisions did not demonstrate a significant deficit. These findings are in agreement with research on non-human primates suggesting that structures in the superior temporal gyrus are important in retaining auditory information over short time spans, and further indicate that the human right temporal area is specialized for this function.
Somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded in controls and in patients with focal lesions in dorsolateral prefrontal cortex (PFCx). Unilateral PFCx lesions increased the amplitude of the P26 component generated in postcentral areas 1 and 2. The amplitudes of the N28, P45 and N67 SEP components recorded over post-rolandic and frontal electrodes were also enhanced by PFCx damage. In contrast, the N19 component generated in postcentral area 3b was unaffected by PFCx lesions. The results indicate that PFCx exerts inhibitory modulation on sensory processing that may be mediated by corticocortical PFCx-parietal connections.
Changes in orienting activity induced by lesions of the hippocampus were studied in 15 unrestrained cats. The orienting reflex was elicited by repetitive stimuli either “indifferent” or familiar to the animal. Electrocoagulations were followed by changes in spontaneous behavior of the animal (docility, reduced spontaneous affective manifestations), and by changes of orienting behavior (somatic reactions of small amplitude accompanied by poor vegetative-affective manifestations). The magnitude of behavioral change was a function of extent of lesions. These changes were due to the postlesion alterations of the control function exerted by the hippocampus upon the general behavior.
Anterograde and retrograde tracing methods including autoradiography, horseradish peroxidase histochemistry and fluorescent dye transport were used to demonstrate that the dorsolateral prefrontal cortex is connected with the hippocampal formation and associated cortical regions by two distinct pathways. Fibers forming a lateral pathway travel in the fronto-occipital fasciculus and connect the dorsolateral prefrontal cortex with the fundus of the rhinal sulcus, posterior subdivisions of the parahippocampal gyrus, and the presubiculum. A larger medial pathway forms in the cingulum bundle and terminates in the most caudal part of the presubiculum, as well as in adjacent transitional cortices. These cortices form a caudomedial promontory that is located between the posterior cingulate and prestriate areas. In all allo- and mesocortical targets of prefrontal cortex, labeled terminals form banding patterns reminiscent of the columnar organization of afferent fiber columns in neocortex. The same cytoarchitectonic areas that receive prefrontal afferents issue reciprocal projections. The largest source is the caudomedial lobule including its presubicular portion. Neurons in the parahippocampal gyrus and adjacent presubiculum also are retrogradely labeled following implants of horseradish peroxidase or injection of fluorescent dyes into prefrontal cortex. In addition, subicular neurons project to the prefrontal cortex although the subiculum does not appear to receive prefrontal afferent input. These findings emphasize that multiple channels of communication link the dorsolateral prefrontal cortex and the hippocampus via the parahippocampal gyrus, subiculum, presubiculum and adjacent transitional cortices. We speculate that each of these prefrontal projections may carry highly specific information into the hippocampus, whereas the reciprocal projections may allow retrieval by prefrontal cortex of memories stored in the hippocampus.