Michael Gazzaniga

Cognitive Neuroscience has many issues with respect to the current field of neuroethics. Cognitive neuroscience can help with some current ethical dilemmas such as does the embryo have the moral status of a human being? Perhaps most importantly cognitive neuroscience is building an understanding of how brain research will instruct us on ideas like...

This chapter looks at developments in the split-brain studies during the past fifty years from a personal perspective. It describes experiments in split-brain research and the discovery of the effects of callosal disconnection. It highlights major findings in split-brain research that relate to the problem of consciousness and suggests that it is i...

Society must respond to the growing demand for cognitive enhancement. That response must start by rejecting the idea that 'enhancement' is a dirty word, argue Henry Greely and colleagues.

One question central to all domains of attention research concerns the understanding how attentional capacities are controlled. Accordingly, the study of attentional functioning in split-brain patients has long focused on investigating the degree to which attention is independently controlled in the two cerebral hemispheres. In particular, severing...

Integrating dynamic information across the senses is crucial to survival. However, most laboratory studies have only examined sensory integration for static events. Here we demonstrate that strong crossmodal integration can also occur for an emergent attribute of dynamic arrays, specifically the direction of apparent motion. The results of the pres...

We examined the effect of posture change on the representation of visuotactile space in a split-brain patient using a cross-modal congruency task. Split-brain patient J.W. made speeded elevation discrimination responses (up versus down) to a series of tactile targets presented to the index finger or thumb of his right hand. We report congruency eff...

Recent neurophysiological research in the monkey has revealed bimodal neuronal cells with both tactile receptive fields on the hand and visual receptive fields that follow the hands as they move, suggesting the existence of a bimodal map of visuotactile space. Using a cross-modal congruency task, we examined the representation of visuotactile space...

Joint attention, the tendency to spontaneously direct attention to where someone else is looking, has been thought to occur because eye direction provides a reliable cue to the presence of important events in the environment. We have discovered, however, that adults will shift their attention to where a schematic face is looking--even when gaze dir...

In the past two decades, neuroscientific investigations such as postmortem and neuroimaging studies have revealed a variety of regional brain disturbances in major mental illnesses. These emerging findings are difficult to appreciate fully without a sufficient grasp of the neuroanatomy of the regions identified in these studies. The authors have de...

Previous psychophysical and neuroimaging studies suggest that perceiving the handedness of a visually presented hand depends on sensorimotor processes that are specific to the limb of the stimulus and that may be controlled by the cerebral hemisphere contralateral to the limb. Therefore, it was hypothesized that disconnection between cerebral hemis...

During the decade following the first edition of this book, methodological advances in a number of related disciplines have greatly enriched our fund of knowledge concerning the role of the corpus callosum in higher brain functions. At the microanatomical level, new tracer techniques have provided a detailed picture of interhemispheric connectivity...

Examination of structure-function correlates in the human brain reveals that there is a high degree of functional specificity in the information transmitted over neural systems. It also appears that the human brain has a modular organization consisting of identifiable component processes that participate in the generation of a cognitive state. The...

While classical and current theories of pain emphasize the critical role of central neural pathways that represent the contralateral body surface and cross within the spinal cord, the role of neural input representing the ipsilateral body surface is uncertain. In the present experiments with a complete corpus callosum-sectioned patient, both tactil...

A commissurotomy patient with limited language in the right hemisphere was tested for ability to recognize direct and indirect antonyms. Normal subjects performing this task recognize direct antonyms faster than indirect. The patient's left hemisphere responded normally, but his right showed no difference in response to direct and indirect antonyms...

A series of studies are reported that suggest the parietal lobe of humans is involved in the establishment of spatial referents in gravitational space. This function goes beyond the more elementary function of processing retinotopic information and most likely plays an important role in governing a wide range of locomotor activities. It is also sug...

Following commissurotomy, it is usually the case that information presented to the left hemisphere can be named and described, while information presented to the mute, right hemisphere cannot be spoken about. In the present study, it was discovered that under special test conditions, an MRI-verified, callosally sectioned adult could name or write a...

Behavioral testing following division of the corpus callosum has shown that the anterior commissure can transfer information related to visual tasks interhemispherically in nonhuman primates but not in humans. We have found that the ratio of anterior commissure cross-sectional area to total neocortical commissural area is significantly greater for...

MRI imaging using recovery and spin-echo techniques was carried out on three patients after surgical section of the corpus callosum to control intractable epilepsy. The scans revealed that the total callosotomy had been obtained in two patients, while partial sparing of splenial and rostral fibers was seen in the third.

Information presented to each hemisphere of the commissurotomy patient is available only to the stimulated hemisphere. Despite this, the hemispheres have access to a common pool of processing resources, which, under conditions of demanding bilateral stimulation, is distributed between the hemispheres.

This chapter discusses the observations from split-brain man. The early claims by split-brain researchers that splitting the cerebrum essentially doubled the mental apparatus are met with (1) awe, (2) skepticism, or (3) incredulity. It is quite pleasant dealing with those people in the first category. As for the skeptics, their rightly placed argum...

A persistent phenomenon in the neurological clinic is that patients who experience mild to severe cerebral damage and who show at the onset serious behavioral deficits usually recover some, if not all, of the lost function. While this is an enormous benefit to the patient, for which all are thankful, it is downright disconcerting to the neuropsycho...

It is indeed a pleasure and an honor to be included in this symposium in commemoration of OTFRID FOERSTER. Reading over Dr. ZÜLCH’s elegant summary of FOERSTER’s interests one is reminded of the scope and influence FOERSTER had on brain research. He had, of course, a particular fascination for the problem of localization of function and it is this...

In a short-term recognition memory task, Ss were given relational imagery and rehearsal coding strategies in different sessions, with probes presented to the left or right cerebral hemisphere. Consistent with a model of separate processing systems for verbally and visually coded information, Ss yielded significantly faster response latencies for pr...

Three split-brain monkeys successfully learned a visual pattern discrimination in one hemisphere in a training sequence that did not make use of a reward. The results suggest that reward information is not a necessary condition for learning.

The effects of a presumed unilateral brain lesion on language functions are examined in a case of 'pure word deafness.' The patient was totally impaired in his auditory perception of speech while retaining much written comprehension, spontaneous speech and writing. As is usually the case, the word deafness was contaminated by some indication of aud...

Not Available Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints

Natural language assessment and artificial language training were undertaken in seven globally aphasic patients sustaining left hemisphere damage. Initial assessment of natural language showed some semantic knowledge but no syntactic or grammatical ability. Words were distinguished fron nonwords and words were spelled in the absence of semantic com...

Subjects asked to match a word presented in one visual field to a previously exposed word presented across the fields demonstrated higher accuracy for words in the left visual field. This result is contrary to existing views of right field superiority in word recognition. The left field superiority suggests that word recognition is a multistage pro...

Subjects were tested for their ability to match words sequentially presented to the same visual field and to different visual fields. When the match was made between visual fields the error rate was significantly greater than when the match was made within fields. The combining of information from both visual fields requires its transmission across...

The manifested dominance split-brain monkeys usually show for performing visual tasks through one hemisphere, when perceptual information is equally available to both, was analyzed. Three split-brain monkeys, each being trained similar yet different discriminations to each hemisphere, were allowed the opportunity to choose between the two problems...

Right hemisphere language and speech capacity was further analyzed in brain-bisected patients. The results indicate that little or no syntactic capability exists in the right hemisphere. The only semantic dimension that was comprehended in a series of pictorial-verbal matching tests was the affirmative-negative. Moreover, earlier indications of a r...

Three experienced split-brain monkeys were taught a visual pattern discrimination in one eye hemisphere and shifted to an FR-2 schedule of reinforcement. The opposite hemisphere was then allowed to view the discrimination on thenon-reinforced trials. Under this condition the untrained hemisphere began disrupting the performance of the trained hemis...

Using split-brain monkeys, reversal behavior was observed under two conditions. In the first both hemispheres viewed the discrimination cues. Previous to this one hemisphere had been taught to respond to one cue and the other hemisphere had learned the opposite response. The task was reversed each time after responding to one cue reached criterion....

Three experienced split-brain monkeys were taught a visual pattern discrimination in one eye hemisphere. After several hundred over-learning trials, the opposite untrained eye hemisphere was allowed to observe 40 perfect trials. Subsequently, ten test trials in which every response was reinforced were delivered exclusively to the untrained hemisphe...

The following studies were aimed at further clarification of certain of the functional effects produced by brain bisection in primates. They involved also the application and implications of brain bisection for problems of normal cerebral organization. In particular, extensive functional testing was carried out on two human patients in whom brain b...

Performed 2 simple choice RT experiments using tachistoscopic flashes containing a dot to the right or left of fixation or a blank field as stimuli. Exp. I required a verbal response and Exp. II a manual response to the presence or absence of a dot. Median verbal RTs to a right dot averaged 386 msec., while those to a left dot or to a blank field a...

We tested the ability of split-brain humans to locate accurately a point in space using an ipsilateral hemisphere-hand combination. Positive results were only obtained when the non-seeing hemisphere had target information in the form of knowledge of eye position. The results confirm the view that a main mechanism in the interhemispheric integration...

To learn a simple pattern discrimination an organism must be able to integrate its response experience with reinforcement information. The importance of cortical pathways in this integration can be tested with people who have had midline section of the corpus callosum and anterior commissure in an effort to control the interhemispheric spread of se...

It was proposed that split-brain monkeys are able to perform ipsilateral eye-hand response because the seeing hemisphere can cross-cue the blind hemisphere, which is in major motor control of the arm, by orienting toward a point in space and, thereby, allow for the bilateral registration of head, neck, and eye position. In the present study, accura...

[Introduction] Until a few years ago, prevailing views regarding the syndrome of the corpus callosum in man were based very largely on the studies of Akelaitis and his co-workers (Akelaitis et al. 1942; Akelaitis 1944). Using a wide variety of tests Akelaitis examined a series of more than two dozen patients with partial and complete surgical secti...

The BASIC picture of the cerebral deconnection or split-brain syndrome1 has been extended and elaborated in recent years through the study of some patients in whom cerebral commissurotomy had been carried out by P. J. Vogel at the White Memorial Medical Center, Los Angeles, in an effort to curb severe epileptic seizures not controlled by medication...

Two normal and two split-brain monkeys were trained to respond to increasing amounts of flashed visual information distributed equally in each half visual field. It was found that the brainbisected animals were able to perceive and respond correctly to more information in a given period of time than were the normal controls.

Split-brain monkeys underwent either deep hemispheric disconnection or unilateral cortical ablations in an attempt to determine the neural mechanisms underlying ipsilateral eye-hand coordination. The results indicate that the responding hand is not in any direct way controlled by visual processes of the ipsilateral hemisphere. Instead, it is sugges...

Split-brain monkeys permanently fitted with goggles equipped with a red filter over one eye and a blue filter over the other were placed in a specially-designed testing apparatus which could be illuminated by either red or blue light. They were trained and maintained in blue light, thereby allowing vision through only the eye covered with the blue...

The performance of 2 choice reactions, 1 with each hand, in response to 2 visual discrimination tasks presented simultaneously, 1 in each ½ of the visual field, normally takes much longer than the performance of either 1 alone. In commissurotomized human patients, however, the double task was performed as rapidly as the single task. The results con...

Variable partial midline surgery on monkeys has revealed several characteristics of interhemispheric communication of visually learned pattern discriminations. The results show both that interhemispheric communication of visual information in the commissure-intact animal need not be immediate, and that when communication does occur transmission inv...

Seven chiasm-forebrain-split monkeys (Macaca nemestrina) were trained to perform, through one eye, a variety of visual discrimination problems by pushing with one hand the correct one of two black and white patterns presented simultaneously side by side. After learning with the first hand was completed, the other hand was tested and the extent of t...

A variety of basic somatosensory tests carried out on a patient with surgical section of the cerebral commissures revealed a marked separation of somesthetic effects from right and left extremities and from right and left sides of the trunk. Predominantly contralateral projection of somesthesis was evident; the presence of any ipsilateral represent...

Three normal pigtail monkeys (Macaca nemestrina) were trained to perform a visual discrimination problem by pushing with a finger on the correct one of two black and white patterns presented simultaneously side by side. Use of right and left hands was equalized by forced alternation every twenty trials. When the monkeys had learned the discriminati...

It has been possible in studies of callosum-sectioned cats and monkeys in recent years to obtain consistent demonstration of a variety of interhemispheric integrational functions mediated by the corpus callosum.(1,2) These animal findings stand in marked contrast to the apparent lack of corresponding functional deficits produced by similar surgery...