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Biomedical subjects

A Carmon

Publications and source records attributed to A Carmon.

15 recordsLinked to original sources
PubMed1978

Correlation of subjective pain experience with cerebral evoked responses to noxious thermal stimulations.

The relationships between different parameters of the evoked cerebral response to noxious thermal stimulation, stimulus intensity, and subjective pain were investigated in seven normal human volunteers. The evoked response was characterized by late events: a small negative peak at 164--180 ms, followed by a high amplitude positive peak at 372--391 ms. The only correlation found in this study was between the amplitude of the positive component and the qualitative and quantitative aspects of the verbal report of pain. This was manifested by a linear trend of association: an increase in the evoked response amplitude was accompanied by an increase in the magnitude of the subjective sensation. The findings suggest that the evoked response to noxious heat reflects not a mere transduction of the physical parameters of the stimulus, but rather a complex interpretative action at the cerebral level.

Evoked Potentials↗
PubMed1977

Responses of paranoid and nonparanoid schizophrenics in a dichotic listening task.

Differences in attentional processes between normals, paranoid schizophrenics, and nonparanoid schizophrenics were studied by delivering dichotically presented digits for identification. Thirty paranoid schizophrenics (20 acute and 10 chronic), 30 nonparanoid schizophrenics (20 acute and 10 chronic), and 20 normal controls were tested. The data were analyzed in terms of the overall level of correct identification of stimuli presented to the two ears, the number of shifts in report from one ear to the other, and the magnitude of ear differences in recall. The results showed that overall level of performance was higher for the normals than for the schizophrenics; the number of ear shifts was greater for normals and nonparanoid than for paranoid schizophrenics; and ear differences were biggest for the paranoid schizophrenics and smallest for the normals. The results were interpreted in terms of differences in attentional style and rate of information processing.

Adolescent↗
PubMed1977

Retraining in literal alexia: substitution of a right hemisphere perceptual strategy for impaired left hemispheric processing.

An adult patient with literal alexia, agraphia, slight anomia, and dyscalculia due to a left hemisphere infarct showed lack of sequential skills while pattern recognition remained intact. Some words were recognized as patterns, but could not be read phonetically. Therapy concentrated on forming an association of the visual pattern of the complete word with the retained auditory pattern. In this way the patient learned to read several hundred words and short phrases, even as anomia worsened. The patterns learned could not be generalized to noun declension or verb conjugation, or broken into smaller words. This learning process is characteristic of right hemispheric skills which were utilized as left hemispheric functions deteriorated.

Agraphia↗
PubMed1976

Evoked cerebral responses to noxious thermal stimuli in humans.

Brief pulses of Laser emitted radiant heat were used to induce cutaneous painful sensations in human volunteers. Accurate timing of the stimuli permitted recording of scalp averaged evoked potentials. A late negative-positive component of the EP which correlated in amplitude with the subjective sensation was observed in four subjects. The latency of this component (130-160 msec) correlated with stimulus intensity.

Brain↗
PubMed1976

Interictal regional cerebral blood flow in patients with partial seizures.

Interictal regional cerebral blood flow was determined in 11 adult patients with partial epilepsy and lateralized electroencephalographic abnormalities by means of the xenon 133 intracarotid injection method. A hemispheric area demonstrating significantly low regional cerebral blood flow values as compared with the hemispheric mean cerebral blood flow was observed in each of the patients. In 10 of the 11 patients the localized reduced regional cerebral blood flow levels deviated significantly from levels obtained from parallel regions and hemispheres of normal controls. In the majority of patients, the site of low regional cerebral blood flow closely correlated with the clinical type of partial seizures and/or the site of main electroencephalographic abnormality. On the basis of these data, we suggest that the epileptogenic focus responsible for the partial seizures may be localized within the hemispheric area demonstrating the abnormal regional cerebral blood flow reduction.

Adult↗
PubMed1976

On time space and the cerebral hemispheres: a theoretical note.

The two well know dichotomies in hemispheric functions--temporal-spatial, and analysis-synthesis (extraction-integration)--are combined in a unified theory of cerebral dominance. The two dichotomies are first considered within the framework of a two-stage model of information processing, and subsequently reduced to the extraction and integration operations performed at each of the two stages. At the first stage, the respective operations of extraction and integration applied on the sensory stream yield the spatiotemporal organization of events. At the second stage, these operations are expressed in progressively more complex organizations such as verbal coding and pictorial imagery. The model is finally generalized into a multiple-stage model. Some empirical consequences are derived.

Dominance, Cerebral↗
PubMed1976

Objective instrumental memory and performance tests for evaluation of patients with brain damage: a search for a behavioral diagnostic tool.

Cognition and performance of patients with localized and diffuse brain damage was evaluated through the application of objective perceptual testing. A series of visual perceptual and verbal tests, memory tests, as well as reaction time tasks were administered to the patients by logic programming equipment. In order to avoid a bias due to communicative disorders, all responses were motor, and achievement was scored in terms of correct identification and latencies of response. Previously established norms based on a large sample of non-brain-damaged hospitalized patients served to standardize the performance of the brain-damaged patient since preliminary results showed that age and educational level constitute an important variable affecting performance of the control group. The achievement of brain-damaged patients, corrected for these factors, was impaired significantly in all tests with respect to both recognition and speed of performance. Lateralized effects of brain damage were not significantly demonstrated. However, when the performance was analyzed with respect to the locus of visual input, it was found that patients with right hemispheric lesions showed impairment mainly on perception of figurative material, and that this deficit was more apparent in the left visual field. Conversely, patients with left hemispheric lesions tended to show impairment on perception of visually presented verbal material when the input was delivered to the right visual field.

Adolescent↗
PubMed1975

Correlation between regional cerebral blood flow and EEG frequency in the contralateral hemisphere in acute cerebral infarction.

The relationship between the rCBF and the electroencephalographic (EEG) frequency was investigated in the contralateral hemisphere of 22 patients with acute cerebral infarction. Reduced rCBF was observed in all patients studied. The degree of rCBF reduction was mild, moderate, or severe and ranged between 6 and 80% from the lowest age-matched normal values obtained in our laboratory. The frequency indices remained within normal limits (mean - 10.4 Hz) in 16 patients. Slower frequencies (mean - 6.3 Hz) were recorded in 6 patients. No correlation was found between the two parameters (P = 0.89). Both the EEG frequency and the rCBF are known to be closely related to the cerebral metabolic rate. The observed rCBF depression without concomitant changes in the EEG frequency raises the question of the role of globally-reduced cerebral metabolism as the cause of rCBF reduction in the noninfarcted hemisphere in stroke patients. Our findings constitute additional evidence that the contralateral hemisphere is involved in the haemodynamic changes occurring in acute cerebral infarction.

Acute Disease↗
PubMed1975

Hand preference in sequential and spatial discrimination tasks.

Hand preference in sensorimotor discrimination tasks was tested on 80 right handed subjects in four experiments. One set of experiments compared the abilities of the two hands to perform sequential tasks. The other set compared spatial abilities of the two hands. Within each set one experiment involved unimanual performance, and the other bimanual performance. The results showed that subjects performed better with their right hand on the bimanual sequential task, and better with their left hand on the bimanual spatial task. No hand preference was found in the unimanual tasks. The results are interpreted as reflecting the differential sensorimotor dominance of the left and right hemispheres for sequential and spatial tasks respectively.

Discrimination Learning↗
PubMedDate not supplied

Comparison of cognition and performance in patients with organic brain damage and psychiatric patients.

A series of cognitive, memory and performance tests were administered to populations of control subjects, brain damaged patients and psychiatric cases. While the overall level of recognition, identification and memory was more impaired in brain damaged than in psychiatric patients, response latencies were found to be of higher significance in the differential diagnosis.

Adult↗