We challenge the position that only the analysis of single patients can allow us to infer normal function from impaired performance. We claim that the focus on group vs. single case studies is unprofitable and that a more useful question is how best to form abstractions of relevance to cognitive theory. In this context, we consider issues concerning the category of "agrammatism."
Cognitive control, the ability to voluntarily guide our behavior, continues to improve throughout adolescence. Below we review the literature on age-related changes in brain function related to response inhibition and working memory, which support cognitive control. Findings from studies using functional magnetic resonance imaging (fMRI) indicate that processing errors, sustaining a cognitive control state, and reaching adult levels of precision, persist through adolescence. Developmental changes in patterns of brain function suggest that core regions of the circuitry underlying cognitive control are on-line early in development. However, age-related changes in localized processes across the brain, and in establishing long range connections that support top-down modulation of behavior, more effective neural processing for optimal mature executive function. While great progress has been made in understanding the age-related changes in brain processes underlying cognitive development, there are still important challenges in developmental neuroimaging methods and the interpretation of data that need to be addressed.
Using functional magnetic resonance imaging (fMRI) and n-back tasks we investigated whether, in 11-13-year-old children, spatial (location) and nonspatial (color) information is differentially processed during visual attention (0-back) and working memory (WM) (2-back) tasks and whether such cognitive task performance, compared to a resting state, results in regional deactivation. The location 0-back task, compared to the color 0-back task, activated segregated areas in the frontal, parietal and occipital cortices whereas no differentially activated voxels were obtained when location and color 2-back tasks were directly contrasted. Several midline cortical areas were less active during 0- and 2-back task performance than resting state. The task-induced deactivation increased with task difficulty as demonstrated by larger deactivation during 2-back than 0-back tasks. The results suggest that, in 11-13-year-old children, the visual attentional network is differently recruited by spatial and nonspatial information processing, but the functional organization of cortical activation in WM in this age group is not based on the type of information processed. Furthermore, 11-13-year-old children exhibited a similar pattern of cortical deactivation that has been reported in adults during cognitive task performance compared to a resting state.
Developmental studies have demonstrated that cognitive processes such as attention, suppression of interference and memory develop throughout childhood and adolescence. However, little is currently known about the development of top-down control mechanisms and their influence on cognitive performance. In the present study, we used functional magnetic resonance imaging to investigate modulation of activity in the ventral visual cortex in healthy 7-11-year-old children and young adults. The participants performed tasks that required attention to either face (Fs task) or scene (Sf task) images while trying to ignore distracting scene or face images, respectively. A face-selective area in the fusiform gyrus (fusiform face area, FFA) and an area responding preferentially to scene images in the parahippocampal gyrus (parahippocampal place area, PPA) were defined using functional localizers. Children responded slower and less accurately in the tasks than adults. In children, the right FFA was less selective to face images and regulation of activity between the Fs and Sf tasks was weaker compared to adults. In the PPA, selectivity to scenes and regulation of activity, there according to the task demands were comparable between children and adults. During the tasks, children activated prefrontal cortical areas including the middle (MFG) and superior (SFG) frontal gyrus more than adults. Functional connectivity between the right FFA and left MFG was stronger in adults than children in the Fs task. Children, on the other hand, had stronger functional connectivity than adults in the Sf task between the right FFA and right PPA and between right MFG and medial SFG. There were no group differences in the functional connectivity between the PPA and the prefrontal cortex (PFC). Together the results suggest that, in 7-11-year-old children, the FFA is still immature, whereas the selectivity to scenes and regulation of activity in the PPA is comparable to adults. The results also indicated functional immaturity of the PFC in children compared to adults and weaker connectivity between the PFC and the rFFA, explaining the weaker regulation of activity in the rFFA between the Fs and Sf tasks.
A theory is proposed to account for unawareness of blindness, hemianopsia, and hemiplegia, and for phantom limb after amputation. It is assumed that interruption of a sensory pathway at any level--from peripheral nerve to primary sensory cortex--is not associated with any immediate sensory experience that uniquely specifies the defect. Instead the sensory loss must be discovered by a process of self-observation and inference. Discovery is easy for defects that create major functional disability, such as total blindness. Hence unawareness of total blindness occurs only in association with severe intellectual impairment, precluding the required self-observation and inference. In contrast, hemianopsia is difficult to discover because several mechanisms automatically compensate the defect effectively. Thus unawareness of hemianopsia is common, even in intellectually normal individuals. Insensate fields are often the source of suggested (false) percepts, because no information from such a field specifies the absence of a sensory stimulus. The most powerful source of suggestion is sensory activity in uninvolved portions of the affected sensory field. Thus hemianopsics may perceive complete geometric forms when only incomplete forms are shown and the missing portion falls in the hemianopsic fields. Such perceptual completion also occurs in hemianesthetic hemiplegics, creating the illusion that there are normally functioning limbs on the affected side. This perceptual completion increases the difficulty of discovery of hemianesthetic hemiplegia, but the disability is still sufficiently obvious that some additional cognitive impairment is invariably present in patients with lasting unawareness of hemiplegia. Phantom limb after amputation is the product of perceptual completion without associated cognitive impairment. The patient with phantom limb is thus aware of the illusory quality of his phantom. Some insight into the neural basis of perceptual completion and of unawareness of sensory loss may derive from considering sensory systems and associative cortex as parallel-distributed processing mechanisms.
This study tested Annett's right-shift theory on spatial ability with two samples from China. The Vandenberg Mental Rotation Test (MRT), Edinburgh Handedness Inventory, and Family Handedness Questionnaire were administered to 266 high school students and 297 undergraduates. We found very few r++ or r-- among Chinese students. Most Chinese are either moderately right-handed or ambidextrous. Consistent with Casey's finding, we found using different methods to classify handedness leads to different conclusions. However, we did not find the effect of familial handedness that Casey found. Visual strategy is related to success on the MRT but handedness is not.
This review aims to create a cross-disciplinary framework for understanding the perception of control. Although, the personality trait locus of control, the most common measure of control perception, has traditionally been regarded as a product of social learning, it may have biological antecedents as well. It is suggested that control perception follows from the brain's capacity for self regulation, leading to flexible and goal directed behaviours. To this account, a model is presented which spans several levels of analyses. On a behavioural level, control perception may be a corollary of emotion regulation, executive functions, and social cognition. On a neural level, these self-regulatory functions are substantiated in part by the dorsolateral and ventral prefrontal cortex and the anterior cingulate cortex. In addition, a possible role of subcortical-cortical dopamine pathways underlying control perception is discussed.
We hypothesized that the right hemisphere would be superior to the left hemisphere in remembering having seen a specific picture before, given its superiority in perceptually encoding specific aspects of visual form. A large set of pictures (N=1500) of animals, human faces, artifacts, landscapes, and art paintings were shown for 2s in central vision, or tachistoscopically (for 100ms) in each half visual field, to normal participants who were then tested 1-6 days later for their recognition. Images that were presented initially to the right hemisphere were better recognized than those presented to the left hemisphere. These results, obtained with participants with intact brains, large number of stimuli, and long retention delays, are consistent with previously described hemispheric differences in the memory of split-brain patients.
The relationship between leisure activities and development of cognitive impairment in aging has been the subject of recent research. We examined television viewing in association with risk of developing Alzheimer's disease (AD) in a case-control study. Given recent focus on the importance of intellectually stimulating activities as preventive measures against cognitive decline, it is important to examine the effects of less stimulating but common activities. Data are from 135 Alzheimer's disease cases and 331 healthy controls. Demographic characteristics and life history questionnaire responses on the number of hours spent on 26 leisure activities during middle-adulthood (ages 40-59) were analyzed. Logistic regression was used to examine the effects of middle-adulthood leisure activities on case vs. control status. Results indicate that for each additional daily hour of middle-adulthood television viewing the associated risk of AD development, controlling for year of birth, gender, income, and education, increased 1.3 times. Participation in intellectually stimulating activities and social activities reduced the associated risk of developing AD. Findings are consistent with the view that participation in non-intellectually stimulating activities is associated with increased risk of developing AD, and suggest television viewing may be a marker of reduced participation in intellectually stimulating activities.
Infants from 16 to 20 weeks were presented with objects moving across a 60-cm distance. Tracking increased between 16 and 18 weeks, reaching increased at 18 weeks, and arm lifts (swipes) showed no age change. A right spatial field bias in tracking disappeared gradually. Swipes occurred most often in front of the object, when it was moving in the center field, presumably as reactions due to spatial proximity. Reaching occurred in the peripheral spatial fields in the younger infants, but in the older infants most often in the center spatial field. Moreover, reaching occurred generally more often toward the left spatial field and predicted the emergence of tracking the left spatial field. Thus, it appeared that a bias in reaching corrected a bias in tracking. Similar effects of limb movements, especially when reaching, were found in the successful treatment of visual neglect patients in neuropsychological research.
Recently there has been interest in an unusual neuropsychological disorder in which the patient copies a complex drawing in a position which is grossly rotated relative to the original. This disorder is of interest partly because of its relationship to current theories of the process of object recognition, but the range of performances typically seen, as well as its anatomical correlates, remain obscure. We report 16 cases who produced grossly rotated drawings of the Rey and Taylor Complex Figures. These patients were drawn from an unselected series of 240 cases, with a wide variety of lesion types and sites. The performances of the 16 patients displayed striking similarities. We describe the formal features of these drawings and plot their anatomical correlates.
Patterns of facial asymmetry (i.e., extent of movement) as a function of elicitation condition, emotional valence, and sex of subjects are examined. Thirty-seven right-handed adult males and females were videotaped making positive and negative expressions of emotion under posed (verbal, visual) and spontaneous conditions. There were no differences in facial asymmetry as a function of condition. Overall, expressions were significantly left-sided, a finding implicating the right hemisphere. When sex and valence were considered, negative expressions were left-sided for all subjects, while positive expressions were left-sided for males only. Further, positive expressions were significantly less lateralized than negative ones for females. Measures of hemiface mobility and ocular dominance did not mediate these patterns of facial lateralization.
This study investigated sex differences in spatial memory using a human analogue of the Radial Arm Maze: a revision on the Nine Box Maze originally developed by called the 17-Box Maze Test herein. The task encourages allocentric spatial processing, dissociates object from spatial memory, and incorporates a within-participants design to provide measures of location and object, working and reference memory. Healthy adult males and females (26 per group) were administered the 17-Box Maze Test, as well as mental rotation and a verbal IQ test. Females made significantly fewer errors on this task than males. However, post hoc analysis revealed that the significant sex difference was specific to object, rather than location, memory measures. These were medium to large effect sizes. The findings raise the issue of task- and component-specific sexual dimorphism in cognitive mapping.
The nineteenth century witnessed many advances in neuroscientific concepts. Among the notable are Charles Bell's (1774-1842) and François Magendie's (1783-1855) identification of sensory and motor pathways, Thomas Henry Huxley's (1825-1895) elaboration of evolutionary theory in the context of comparative neuroanatomy, and Emile Du Bois-Reymond's (1818-1896) and Hermann von Helmholtz's (1821-1894) work in experimental neurophysiology and on the concept of nervous energy. In Germany, the idea that the nervous system consisted of two elements, one that generated nervous energy and another that conducted it throughout the body, had wide currency in mid-nineteenth century. In France, Pierre Jean Georges Cabanis (1757-1808), physician, philosopher, and one of the founders of modern psychophysiology, argued that the brain is the part of the body in which electricity is stored. In his Rapports du Physique et du Moral de l'Homme, published between 1796 and 1802 (translated into German under the title Verhältnis der Seele zum Körper (1808)), Cabanis proposed new ideas on brain function, on the brain's own sensibility, on the concept of will, and on the chemical basis of nervous activity. In the Rapports Cabanis proposed a theory of how brain and nerves relate to thought and behavior. Foreshadowing later developments in neuropsychology, he suggested that different parts of the nervous system have separate functions. Despite the fact that Cabanis had many interesting ideas about brain function, he has been largely ignored by historians of neuroscience; e. g., he is mentioned briefly in Clark and Jacyna (1989), in only two footnotes in Neuburger (1897/1981), and not at all in Finger (1994). Cabanis's far-reaching theory of how the brain works helped shape understanding of the general notion of nervous energy in nineteenth-century European neuroscience.
Schroeder van der Kolk is regarded as the founder of Dutch psychiatry and neurology. This paper describes his vitalistic views on the relation between body and soul, as formulated by him in a series of lectures. These lectures were intended to counteract the materialistic tendencies of some of Schroeder van der Kolk's French and German contemporaries. It is argued that Schroeder van der Kolk can be regarded as the transition in Holland from the "Naturphilosophie" approach to the modern experimental approach in physiology.
Voice and face recognition were tested in 21 left- and 9 right-hemisphere-damaged patients. Test materials were photographs and recordings of famous political and entertainment personalities. Pathological face recognition (prosopagnosia) and voice recognition (phonagnosia) were both significantly more prevalent in the right-hemisphere group. Only one instance of prosopagnosia and one of phonagnosia were observed in the left-hemisphere group, all of whom were aphasic. Of the right-hemisphere cases, there were four instances of each agnosia, with three patients showing a dual impairment. These findings are discussed in relation to differential modes of processing by the two cerebral hemispheres.
Roberts Bartholow's 1874 experiment on Mary Rafferty is widely cited as the first demonstration, by direct application of stimulating electrodes, of the motor excitability of the human cerebral cortex. The many accounts of the experiment, however, leave certain questions and details unexamined or unresolved, especially about Bartholow's goals, the nature and quality of the evidence, and the experiment's role in the history of theory and research on localisation of function. In this article, we try to fill these gaps and to tell the full story. We describe Bartholow's career up to 1874, review the theoretical and empirical background for the experiment, and present Bartholow's own account of the experiment as well as those of his supporters and critics. We then present our own analysis, assess the experiment's influence on contemporaneous scientific opinion about cortical excitability, and trace its citation record into our own time. We also review and assess ethical criticisms of Bartholow and their effects on his career, and we close by discussing the role we think the experiment deserves to play in the history of theory and research on cortical excitability.
A critique is presented of the chimeric face task used as a measure of cerebral laterality by M. J. Roszkowski and G. E. Snelbecker (1982, Brain and Cognition, 1, 404-409). Problems arise because the faces used are not true mirror images of each other, but in fact differ in facial details. Data are presented to illustrate that the earlier results are not caused by cerebral laterality but by the fact that the two drawings are not equally happy--even when placed in the same left-right orientation.
In a recent article in this journal, Hellige (Brain and Cognition, 2, 199-203, 1983) presented a critique of the chimeric-face technique that was used by us to validate a hand preference questionnaire. Data were presented by Hellige to show that the left visual field (LVF) bias that occurs on this task is due primarily to differences in detail in the features of the two faces and not because of right hemisphere dominance for face perception. In our rebuttal, we acknowledge that the two faces are not mirror-image duplicates of each other, but contend that this fact does not explain why differences between left-handers and right-handers have been observed on this task. Further data on the role of handedness as well as other variables impacting on this task are presented. A possible explanation is also offered for the rather small extent of LVF bias that Hellige obtained when he used corrected (i.e., true mirror-image) versions of Jaynes' chimeric faces.
A reanalysis of data from left-handers presented by A. Searleman, C. Porac, and S. Coren, (1984, Brain and Cognition, 3, 86–93) cautions against premature conclusions that an inverted handwriting posture is more prevalent for sinistral men with leftward lateral preferences and for women with rightward or mixed lateral preferences. Although this may eventually prove to be true, the findings of Searleman et al. (1984) are insufficient for supporting this inference.
Schiff and Lamon (1989) proposed that unilateral face contractions induce positive or negative changes in emotion depending on the side of contraction; support for this proposal, however, has been mixed. In a new test, 40 right-handed and 38 left-handed men performed four alternating face contractions (LRLR or RLRL) and, after each one, completed a different version of the Depression Adjective Checklist (Lubin, 1994). A repeated-measures ANCOVA failed to reveal any significant effect of side of face contraction or handedness on direction of emotion change. Instead, regardless of side of contraction, the subjects' negative emotional state increased significantly across the four contractions with the degree of change being significantly related to the subjects' reported level of difficulty in holding the contraction irrespective of whether the more difficult side was the left or the right.
An algebraic analysis of the procedures used in "Neuroelectric Concepts: Form-Color Classification," Brain and Cognition, 21, 226-246 (1993) by William J. Hudspeth reveals that the article's results are artifactual, having been produced by the introduction of strong linear dependencies during data transformation. The same pattern of principal results is shown to obtain by applying Hudspeth's procedures both to arbitrarily selected EP input data having no connection to form or color discrimination, and to waveforms composed of sequences of random numbers.
Abnormal smooth pursuit eye-tracking is one of the most replicated deficits in the psychophysiological literature in schizophrenia [Levy, D. L., Holzman, P. S., Matthysse, S., & Mendell, N. R. (1993). Eye tracking dysfunction and schizophrenia: A critical perspective. Schizophrenia Bulletin, 19, 461-505]. We used meta-analytic procedures to quantify patient-control differences in eye-tracking and to evaluate potential moderators of effect size including patient and target characteristics and characteristics of the control population (matched or not). The magnitude of patient-control differences in pursuit depended on the measure. Global measures had large effect sizes. Among specific measures, maintenance gain and leading saccades yielded large effect sizes, with gain also yielding the narrowest confidence interval. Effect sizes associated with specific measures of smooth pursuit vs. specific measures of intrusive saccades did not clearly implicate one system over the other. Patient demographics and target characteristics generally had little influence on effect sizes. However, studies that failed to sex-match patients and controls tended to have smaller effect sizes for maintenance gain and catch-up saccade rate. Average effect sizes and confidence limits for global measures of pursuit and for maintenance gain place these measures alongside the very strongest neurocognitive measures in the literature [Heinrichs, R. W. (2004). Meta-analysis, and the science of schizophrenia: Variant evidence or evidence of variants? Neuroscience and Biobehavioral Reviews, 28, 379-394] for distinguishing between patients with schizophrenia and controls.
Studies of phantom limb in cases of congenital (aplasic) absence of limb have provided inadequate evidence concerning the innate neurological substrate responsible for the phantom. In this study we review evidence from ultrasonic and behavioral studies of hand-mouth coordination in utero and in early infancy, neurobiological studies in primates, and studies of neural reorganization following amputation. We suggest two complementary hypotheses to explain aplasic phantoms. First, aplasic phantoms are based on the existence of specific neural circuitry associated with innate motor schemas, such as the neural matrix responsible for early hand-mouth coordination. Second, aplasic phantoms are modified by mechanisms that involve a reorganization of neural representations of the missing limb within a complex network involving both cortical and subcortical structures.
The present paper re-analyzes anatomical and clinical data of a previous case report (Summer, 2002). In this case study, a patient with severe neuropsychological and behavioral impairments is described and it is claimed that these impairments are causally linked to an right thalamic lesion. A simple method how to perform a lesion analysis is introduced which shows that PD's lesion was a striatocapsular hematoma, and not a thalamic bleeding. The results of this anatomical re-analysis challenge the original behavioral-lesion hypothesis and emphasize the importance to provide appropriate data on brain lesions and clinical findings in neuropsychological case reports.
Holistic processing of faces is characterized by encoding of the face as a single stimulus. This study employed a composite face task to examine whether holistic processing varies when attention is restricted to the top as compared to the bottom half of the face, and whether evidence of holistic processing would be observed in event-related potentials. Analyses of behavioral data showed that spatial misalignment of the face halves disrupted holistic processing and enhanced detection of repeated attended halves. Effects of misalignment on the N170, VPP and N250 ERP components resembled effects of face inversion. Attention to the top half of the face was associated with faster P1, N170, VPP, and P2 latencies than attending to the bottom, suggesting automatic processing of the eye region. Further, N170 latency effects suggested that structural encoding of the face is facilitated during holistic processing. N250 latency effects reflected task difficulty. Finally, an overall right hemispheric asymmetry was most pronounced when holistic face processing was greatest. Results are discussed in light of recent proposals that holistic face processing is a subtype of configural face processing.
In an Internet study unrelated to handedness, 134,317 female and 120,783 male participants answered a graded question as to which hand they preferred for writing. This allowed determination of hand preference patterns across 7 ethnic groups. Sex differences in left-handedness were found in 4 ethnic groups, favoring males, while no significant sex differences were found in three of the groups. Prevalence of left-handedness in the largest of the ethnic groups (self-labelled as "White") was comparable to contemporary hand preference data for this group [Gilbert, A. N., & Wysocki, C. J. (1992). Hand preference and age in the United states. Neuropsychologia, 30, 601-608] but the prevalence of left-handedness in individuals >70 years of age was considerably higher in the present study. Individuals who indicated "either" hand for writing preference had significantly lower spatial performance (mental rotation task) and significantly higher prevalence of hyperactivity, dyslexia, asthma than individuals who had clear left or right hand preferences, in support of Crow et al. [Crow, T., Crow, L., Done, D., & Leask, S. (1998). Relative hand skill predicts academic ability: global deficits at the point of hemispheric indecision. Neuropsychologia, 36, 1275-1282]. Similarly, an association of writing hand preference and non-heterosexual orientation was clearest for individuals with "either" writing hand responses. We conclude that contradictions in the literature as to whether or not these variables are linked to handedness stem largely from different definitions of hand preference. Due to a lack of statistical power in most studies in the literature, the "either" hand writing preference group that yielded the most salient results in this study is not normally available for analysis.
A general theory is proposed that attributes the origins of human intelligence to an expansion of dopaminergic systems in human cognition. Dopamine is postulated to be the key neurotransmitter regulating six predominantly left-hemispheric cognitive skills critical to human language and thought: motor planning, working memory, cognitive flexibility, abstract reasoning, temporal analysis/sequencing, and generativity. A dopaminergic expansion during early hominid evolution could have enabled successful chase-hunting in the savannas of sub-Saharan Africa, given the critical role of dopamine in counteracting hyperthermia during endurance activity. In turn, changes in physical activity and diet may have further increased cortical dopamine levels by augmenting tyrosine and its conversion to dopamine in the central nervous system (CNS). By means of the regulatory action of dopamine and other substances, the physiological and dietary changes may have contributed to the vertical elongation of the body, increased brain size, and increased cortical convolutedness that occurred during human evolution. Finally, emphasizing the role of dopamine in human intelligence may offer a new perspective on the advanced cognitive reasoning skills in nonprimate lineages such as cetaceans and avians, whose cortical anatomy differs radically from that of primates.
Verbal IQ is usually lower than performance IQ in neonatally identified 47,XXY males. A dermatoglyphic measure reflecting prenatal growth rates and indices of sex-related hormonal functioning are also frequently abnormal in 47,XXY males. This paper presents evidence indicating that a measure of prenatal growth rate predicts right hemispheric specialization for nonverbal processing in extra X males, whereas levels of testosterone, estradiol, luteinizing hormone, and follicle-stimulating hormones do not. Findings are also reported which indicate that the low verbal IQs of 47,XXY males are the result of abnormalities in right hemispheric functioning.
Thirty-two boys with a 47,XXY karyotype were compared with chromosomally normal male controls in their performance on six tasks of hemispheric specialization. The results revealed that the 47,XXY subjects had smaller asymmetries on left hemisphere tasks and larger asymmetries on right hemisphere tasks than controls. Analyses of individual right and left side scores revealed that the atypical lateral asymmetries of the 47,XXYs were due to a shift toward greater right hemisphere involvement on four of the six measures. It was postulated that the slower fetal growth rates of the extra X chromosome group might contribute to their atypical hemispheric specialization and the failure of their left hemisphere to gain dominance over their right in language processing.
This study tested the hypothesis that the recognition of emotions would draw upon anatomically separable brain regions, depending on whether the stimuli were static or explicitly conveyed information regarding actions. We investigated the hypothesis in a rare subject with extensive bilateral brain lesions, patient B., by administering tasks that assessed recognition and naming of emotions from visual and verbal stimuli, some of which depicted actions and some of which did not. B. could not recognize any primary emotion other than happiness, when emotions were shown as static images or given as single verbal labels. By contrast, with the notable exception of disgust, he correctly recognized primary emotions from dynamic displays of facial expressions as well as from stories that described actions. Our findings are consistent with the idea that information about actions is processed in occipitoparietal and dorsal frontal cortices, all of which are intact in B.'s brain. Such information subsequently would be linked to knowledge about emotions that depends on structures mapping somatic states, many of which are also intact in B.'s brain. However, one of these somatosensory structures, the insula, is bilaterally damaged, perhaps accounting for B.'s uniformly impaired recognition of disgust (from both static and action stimuli). Other structures that are damaged in B.'s brain, including bilateral inferior and anterior temporal lobe and medial frontal cortices, appear to be critical for linking perception of static stimuli to recognition of emotions. Thus the retrieval of knowledge regarding emotions draws upon widely distributed and partly distinct sets of neural structures, depending on the attributes of the stimulus.
The present experiment was designed to better understand the impact of positive and negative emotional processing among low- and high-hostile individuals. Based on previous research which found increased sympathovagal balance among low-hostiles to the negative version of the Affective Auditory Verbal Learning Test (AAVL), it was hypothesized that low-hostiles would experience increased cortical arousal to this stimulus whereas their high-hostile counterparts would not. As expected, low-hostiles experienced significantly reduced low-alpha power (7.5-9.5Hz) relative to high-hostiles during the presentation of the negative AAVL. In a replication of prior research, significant primacy and recency effects were noted for the negative and positive word lists, respectively. Results are discussed in terms of cerebral activation theory and the potential impact of emotional processing among high-hostile individuals and their likelihood to develop coronary heart disease.
Visual scanpath recording was used to investigate the information processing strategies used by a prosopagnosic patient, SC, when viewing faces. Compared to controls, SC showed an aberrant pattern of scanning, directing attention away from the internal configuration of facial features (eyes, nose) towards peripheral regions (hair, forehead) of the face. The results suggest that SC's face recognition deficit can be linked to an inability to assemble an accurate and unified face percept due to an abnormal allocation of attention away from the internal face region. Extraction of stimulus attributes necessary for face identity recognition is compromised by an aberrant face scanning pattern.
Contrasts of verbal fluency and automatic speech provide an opportunity to evaluate the neural underpinnings of generativity and flexibility in autism spectrum disorders (ASD).
We used functional magnetic resonance imaging (fMRI) to contrast brain activity in high functioning ASD (n=17, mean verbal IQ=117) and neurotypical (NT; n=20, mean verbal IQ=112) adolescent and young adult males (12-23years). Participants responded to three word generation conditions: automatic speech (reciting months), category fluency, and letter fluency.
Our paradigm closely mirrored behavioral fluency tasks by requiring overt, free recall word generation while controlling for differences in verbal output between the groups and systematically increasing the task demand. The ASD group showed reduced neural response compared to the NT participants during fluency tasks in multiple regions of left anterior and posterior cortices, and sub-cortical structures. Six of these regions fell in cortico-striatal circuits previously linked to repetitive behaviors (Langen, Durston, Kas, van Engeland, & Staal, 2011), and activity in two of them (putamen and thalamus) was negatively correlated with autism repetitive behavior symptoms in the ASD group. In addition, response in left inferior frontal gyrus was differentially modulated in the ASD, relative to the NT, group as a function of task demand.
These data indicate a specific, atypical brain response in ASD to demanding generativity tasks that may have relevance to repetitive behavior symptoms in ASD as well as to difficulties generating original verbal responses.
We report here the case study of a patient (E.C.) with an Asperger syndrome, or autism with quasinormal intelligence, who shows an outstanding ability for three-dimensional drawing of inanimate objects (savant syndrome). An assessment of the subsystems proposed in recent models of object recognition evidenced intact perceptual analysis and identification. The initial (or primal sketch), viewer-centered (or 2-1/2-D), or object-centered (3-D) representations and the recognition and name levels were functional. In contrast, E.C.'s pattern of performance in three different types of tasks converge to suggest an anomaly in the hierarchical organization of the local and global parts of a figure: a local interference effect in incongruent hierarchical visual stimuli, a deficit in relating local parts to global form information in impossible figures, and an absence of feature-grouping in graphic recall. The results are discussed in relation to normal visual perception and to current accounts of the savant syndrome in autism.
The relative participation of left- and right-hemisphere functions in verbal and spatial processing with musical composers, instrumentalists, painters, and non-musicians from student and junior high school populations was investigated. Hemispheric lateralization was related to the outcome of tests measuring spatial orientation, spatial visualization, tactile-visual discrimination, and verbal fluency. The relationship between lateral dominance and cognitive variables was influenced by sex and musical talents and the ability to paint. Males, irrespective of talents, were lateralized stronger than females. These sex differences were due to nonmusicians, only. Male and female composers, instrumentalists, and painters did not differ in language lateralization. Female left-handers showed a marked tendency for reversed language lateralization; left-handed males did not.
Nonverbal learning disabilities (NLD) are characterized by weaknesses in narrative discourse. Thirty-three children (M ag e= 11.7 years), 15 girls and 18 boys, listened to stories to evaluate their narrative comprehension and retelling abilities. Children with NLD (n = 11) performed as poorly as children with verbal impairment (n = 10) on all narrative measures. Compared to typical controls (n = 12), the NLD group was poorer in comprehending inferences, but not facts. They included less of the original content than controls in their story retells, and there were strong trends suggesting fewer utterances and less variety in their vocabulary usage. Results are discussed regarding their implications for understanding the neuropsychological profile of NLD.
This study examined syntactic changes in the spoken discourse of patients with Huntington's (HD) or Parkinson's disease (PD) and explored possible relationships between their syntactic changes and concomitant cognitive and motoric symptoms. Patient and control groups participated in a conversational discourse activity and completed a battery of standardized speech and cognitive tests. The HD group used shorter and fewer grammatically complete utterances than their healthy, age-matched peers, whereas there were no significant syntactic differences between PD patients and their healthy, age-matched peers or between PD and HD patients. Productive syntax abilities in HD and PD were meaningfully related to both neuropsychological and motor speech changes. These findings indicate that patients with subcortical disease, at least those with HD, may present with language production deficits and that these deficits are most likely the product of not only motor speech limitations (i.e., dysarthria) but also underlying cognitive impairments.
Sex differences in the cerebral lateralization of two discrete components of spatial processing were investigated in high and low ability males and females using the dual-task paradigm. In the first phase of the experiment, the results indicated a pattern of right hemispheric control for a spatial visualization component, regardless of sex and ability level. In the processing of the spatial orientation component of spatial ability, high ability males and females showed left hemispheric lateralization, whereas low ability males and females displayed right hemispheric control. In the second phase of this study, it was observed that high ability females and low ability males may use a verbal mediation strategy in processing spatial visualization tasks. No verbal mediation effects were found for the spatial orientation component.
Cognitive functioning was assessed in 69 left-handed males and females with a positive family history of left-handedness and in 77 left-handed and 55 right-handed males and females without familial left-handedness. Compared to females, males performed better on numerical reasoning and on two visuospatial tasks involving spatial manipulations (Figure Rotation and Surface Development). Within the group of left-handers, the multivariate effect for Familial Sinistrality was significant. Left-handers with familial left-handedness exhibited better scores on numerical reasoning, on verbal reasoning, and on two visuospatial tasks involving visual closure (Hidden Figures, Picture Completion) than did left-handers without left-handed relatives. The nonfamilial left-handers also exhibited lower scores on both inductive reasoning tasks when they were compared to their right-handed counterparts. The outcome runs contrary to the prevalent conclusion that left-handers with left-handed relatives are more likely to exhibit lower performances on visuospatial tasks than left-handers without such relatives.
Deaf subjects who use American Sign Language as their primary language generated visual mental images faster than hearing nonsigning subjects when stimuli were initially presented to the right hemisphere. Deaf subjects exhibited a strong right hemisphere advantage for image generation using either categorical or coordinate spatial relations representations. In contrast, hearing subjects showed evidence of left hemisphere processing for categorical spatial relations representations, and no hemispheric asymmetry for coordinate spatial relations representations. The enhanced right hemisphere image generation abilities observed in deaf singers may be linked to a stronger right hemisphere involvement in processing imageable signs and linguistically encoded spatial relations.
There is a substantial disagreement in the existing literature regarding which hemisphere of the brain controls spatial abilities. In an attempt to resolve this dispute, we conducted a meta-analysis to decipher which hemisphere truly dominates and under what circumstances. It was found that across people and situations, the right hemisphere is the more dominant for spatial processing. However, consideration of specific moderator variables yielded a more complex picture. For example, females showed no hemisphere preference while males showed a right hemisphere advantage. Also, no hemisphere preference was indicated for spatial visualization tasks while subjects performing spatial orientation and manual manipulation tasks displayed a predictable right hemisphere preference. These findings are discussed in terms of their implications for exiting theoretical positions as well as future empirical research.
A basic neuropsychological examination of language and praxic abilities was administered to extreme educational groups (100 illiterates and 100 professionals). Subjects were matched according to sex and age (16-25, 26-35, 36-45, 46-55, and 56-65). The following tasks were included: language comprehension, phonological discrimination, naming (objects, figures, and body parts), repetition of words, verbal fluency, calculation, buccofacial and ideomotor praxis, finger alternating movements, meaningless movements, cancellation task, coordinated movements with both hands, and motor impersistence tasks. All the differences between the two educational groups were statistically significant. Two of the eight language tests (phonological discrimination and naming figures) and three of the seven praxic tests (buccofacial praxis, coordinated movements, and cancellation task) showed differences between age groups with a better performance in the younger groups. Calculation tasks and ideomotor praxis showed differences between sexes with a better performance in males. Influence of educational factors in performing routine neuropsychological tests is analyzed.
Executive and memory dysfunctions are among the most frequently reported deficits following a ruptured aneurysm of the anterior communicating artery (ACoA). In order to study the impact of the dysexecutive syndrome on episodic and semantic memory, the data obtained from 59 ACoA patients were examined retrospectively. All patients were assessed on a variety of episodic memory tests (Rey Auditory-Verbal Learning Test, Rey Complex Figure Test, Weschler Memory Scale), semantic memory (verbal fluency), and standardized tests of executive functions (Trail Making Test, Maze tests, Wisconsin Card Sorting Test). There was a strong positive correlation between executive dysfunction and retrieval difficulties in episodic and semantic memory tasks. Comparisons of subgroups of patients with high and low frontal lobe functioning on delayed recall and recognition revealed a significant group X condition interaction in addition to significant group and condition main effects. ACoAs patients with low frontal lobe functioning were particularly deficient in free recall (immediate and delayed) while recognition was equally well preserved in the two subgroups. Neither subgroup presented with an abnormal forgetting over time suggesting a retrieval deficit rather than a true retention impairment.