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Biomedical subjects

S J Dimond

Publications and source records attributed to S J Dimond.

18 recordsLinked to original sources
PubMed1979

Some effects of piracetam (UCB 6215, Nootropyl) on chronic schizophrenia.

A study is described of effects of a nootropic drug on chronic schizophrenia. The nootropic drugs act on the central nervous system with the cerebral cortex as their target. Chronic schizophrenic patients on the drug showed improvement in object naming and in tests where the patient was required to indicate the number of times he had been tapped. Improvements were also noted in learning and memory tasks. In dichotic listening the patients showed a reduction in the amount of incorrect verbal responses produced. There were no improvements in symptom rating or social behaviour rating. These results suggest some cognitive improvement but little if any change in the disease state of the patient.

Adult↗
PubMed1979

Performance by split-brain humans on lateralized vigilance tasks.

Studies are described of the vigilance performance of the cerebral hemispheres of split-brain man. Investigations of visual, auditory and tactual performance are reported for six total commissurotomy patients. The vigilance tasks were lateralized to test the functions of the two hemispheres and make comparison between them. The right hemisphere emerges the superior in its vigilance performance in every case. The results support the association of sustained attention with the functions of the right hemisphere and they suggest that there are different mental mechanisms for selective and sustained attention.

Adult↗
PubMed1979

Tactual and auditory vigilance in split-brain man.

Two studies are reported of tactual and auditory vigilance performance in patients with a split-brain or partial commissurotomy to examine the attentional behaviour of the right and left hemisphere, and to identify defects in attention which may be related to the division of the cerebral commissures. The performance of the right hemisphere on all tasks of sustained attention so far studied was substantially better than that of the left. Considerable depletion of concentration was observed for the total split-brain group but not in patients with partial commissurotomy. One of the more unusual phenomena of the split-brain condition is that gaps of attention, often lasting many seconds, occur predominantly on the left hemisphere. The switch to a different type of signal on the same hemisphere does not stop them but the switching of signals from one hemisphere to another does. The defect is interpreted as a failure of attention peculiar to the individual hemisphere under test.

Adult↗
PubMed1979

Callosal transfer and left-hand anomia in schizophrenia.

The theory of callosal failure in schizophrenia is examined using the test for left-hand anomia. It is argued that if the corpus callosum is affected in schizophrenia with consequent difficulty of transmission between the two sides of the brain, a greater number of left-hand errors should be found in producing the names of objects held by that hand because the speech area of the left hemisphere is no longer available for the description of the perceptions of the left hand. The findings support this view and they confirm the communication failures of the brain related to callosal disturbance.

Adult↗
PubMed1977

Functions of the centre section (trunk) of the corpus callosum in man.

The case is reported of a patient in whom the middle sagittal third of the corpus callosum had been removed for the treatment of an underlying angioma. The special advantages of the case are that the patient is a young, relatively healthy person of normal IQ. The angioma had not interfered with interhemispheric transmission and the patient was described as neurologically normal before operation. After operation left-side neglect and extensive somatic disconnection were seen. A change in the balance between the hemispheres for handedness and ear superiority in dichotic listening was observed. The patient developed an aphasia after operation characterized by a simplification of language, the inavailability of complex ideas and emotional communication. He showed a disorder of memory--'autopragmatic amnesia'--in whice. The patient showed disorders of visuo-spatial transfer. These symptoms are thought to typify a syndrome of the centre trunk region of the corpus callosum, to follow as a direct function of the operation performed upon the callosum, and to illustrate the function of this region of the brain.

Adult↗
PubMed1976

Increase in the power of human memory in normal man through the use of drugs.

Nootropyl (Piracetam) a drug reported to facilitate learning in animals was tested for its effect on man by administering it to normal volunteers. The subjects were given 3x4 capsules at 400 mg per day, in a double blind study. Each subject learned series of words presented as stimuli upon a memory drum. No effects were observed after 7 days but after 14 days verbal learning had significantly increased.

Female↗
PubMed1976

Depletion of attentional capacity after total commissurotomy in man.

The attentional capacity of 6 total commissurotomy patients and 2 partial commissurotomy patients was tested by means of a vigilance task in which signals were flashed to the left or right hemisphere. With complete commissurotomy a gross depletion of attentional capacity was discovered which was absent in the partial commissurotomy patients, whose performance equalled that of normal man. Hemisphere asymmetry was also observed. The left hand was more likely to act in the absence of appropriate signals; the left hemisphere showed none of the expected high level efficiency, displaying, instead, a discontinuous action characterized by gaps and holes in its relation to the stimuli. The results are interpreted to mean that some aspect of consciousness represented by sustained attention is dependent upon hemispheric co-operation and upon the integrity of the cerebral commissures.

Adult↗
PubMed1976

Brain circuits for consciousness.

The question is explored of the location of consciousness in the human brain. The author's own studies of defects of consciousness as the result of the splitting of the corpus callosum are described and disorders of consciousness associated with damage to other specific areas of the brain, are reviewed. A circuit spanning the brain is described which stretches from the parietal lobe at one side to the parietal lobe at the other and includes the splenium of the corpus callosum. The medial banks of the hemispheres, the callosal as well as the cingulate areas, are also thought to be involved.

Brain Mapping↗
PubMedDate not supplied

The functions of the right hemisphere and the brain regions involved in figural matching.

A search for the source within the right hemisphere of its primacy on tests of figural matching was made. Patients with right and left hemisphere damage were studied and comparison was made of response to a shape matching task flashed to the right or the left hemisphere. When the right hemisphere is damaged performance seriously declines whether the patient is tested on the right or the left hemisphere. Studies of the specific location within the right hemisphere indicated widespread but subtotal involvement implicating the frontal, temporal and parietal regions of this hemisphere.

Adolescent↗