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Biomedical subjects

J N Petrovici

Publications and source records attributed to J N Petrovici.

7 recordsLinked to original sources
PubMed1997

Interhemispheric transfer of learning in brain-damaged patients.

The purpose of the present study was to assess some of the mechanisms involved in the compensation of impaired cerebral functions in patients with unilateral brain lesions. Thirty patients with lesions of the left (dominant) hemisphere and 30 patients with lesions of the right (minor) hemispheres were studied. The subjects were blindfolded and submitted to some tests of manual performance, i.e. the relief maze test and identification of geometrical figures. The performances of each hand were determined, before and after ipsilateral and contra-lateral training. A post-training improvement index was also established. The hand related to the damaged hemisphere showed the worse performance. The post-training improvement was lower for the damaged hemisphere. The learning transfer test after contralateral training showed an improvement of the damaged hemisphere significantly greater than that of the healthy one. The authors conclude that in patients with unilateral brain lesions, the healthy hemisphere can compensate for some of the impaired higher cerebral functions by a transfer of information and learning to the damaged one.

Adult↗
PubMed1994

[Time perception in organically healthy and brain damaged subjects].

The aims of this study were to investigate whether brain lesions are associated with an impairment of time judgement and whether there is any relationship between alterations of time experience and the side and localization of brain lesions. References were made to the literature dealing with different definitions of the concept of time and the notions derived from time as a categorial entity, such as time experience, time perception and time awareness. To begin with, the philosophical and psychological approach was considered. There upon definitions as given by the natural sciences, conceptual classifications, phenomenological investigations as well as psychopathological considerations were analysed. Furthermore, the literature on disorders of time judgement was reviewed against the background of alterations of time experience in patients with brain lesions. In the present study patients with definite single brain lesions were examined and compared with a group of normal subjects. Three methods for testing time judgement (method of production, method of reproduction and time estimation) were applied to each subject. The results showed that in a substantial proportion of brain-damaged patients a subjective impression of changes in the rate at which time passed was reported, mostly in form of an apparent slowing down. No difference could be demonstrated between left or right cerebral lesions or between different localizations within one hemisphere. On the testing for objective time judgement the brain-damaged patients showed a tendency to under-or overestimation of time intervals, often exceeding the pre-established normal boundaries by far. We observed a certain "vulnerability" of the right hemisphere on the tasks for time judgement, especially in the case of right-sided parieto-occipital lesions.

Adult↗
PubMed1994

[Recurrent pneumococcal meningitis after splenectomy].

We report the case of a female patient with thrombocytopenic purpura Werlhof. Splenectomy was followed by relapsing pneumococcal meningitis. Particularly, repetitive infections were caused by pneumococcus capsula type 13. This type is not included in the common 23-polyvalent vaccine matter. The necessity of splenectomy in autoimmunological diseases should be considered carefully in the individual case. Patients should be well informed of the high risk of infection after splenectomy and should undergo medical treatment immediately.

Adult↗
PubMed1983

[Speech disorders in tumors of the supplementary motor area].

Ten patients with tumors of the supplementary motor area were observed. Speech blocking is the clinically most frequently occurring function disturbance. With respect to the mechanism representing the basis of speech, speech disturbances occurring in connection with lesions of the supplementary motor area can be divided into two groups: (1) Elementary disturbances, Speech block, reiterations, aphemia (mutism), reduction in speech drive. These phenomena are related to the motor process proper, the initiating of speech. They may occur in case of lesions of one of the two hemispheres. (2) Dysphasic understanding. These disturbances only occur in case of lesions of the speech-dominant hemisphere. The supplementary motor area plays a role especially in the motor control and sequential modulation of speaking and in a lesser degree in the storing and calling off of concepts.

Adult↗
PubMed1980

Speech disturbances following stereotaxic surgery in ventrolateral thalamus.

Patients operated on stereotactically in the ventrolateral thalamic structures show after stimulation or following the operation some disturbances which apparently interfere with cerebral speech mechanisms, i.e. speech arrest, word iterations or recurring utterances, lack of initiative to speak, hypoprosodia, change of the speed of enunciation. These phenomena rather concern motor processes, the initiation of speech, the maintenance and control of speech, fluency and volume. They may occur after lesions or stimulations in any of both hemispheres, however, there is a clear preponderance after lesions or stimulations on the left side. Dysphasic disturbances were observed only as transient phenomena. One can conclude that in this case thalamotomy influences the function of the dominant cortical regions for language rather than subcortical structures concerned with speech function. Differences in verbally expressed cognition between subjects with left-sided and right-sided ventrolateral thalamotomy can be observed, not only in the immediate post-operative period, but also after a much longer interval.

Humans↗
PubMedDate not supplied

[Interhemispheric relations and brain plasticity].

The compensatory role of the contralateral hemisphere in patients with unilateral hemispheric lesions was investigated by a test consisting of learning a maze explored with the index finger commanded by the normal hemisphere. In patients with lesions of the left hemisphere training of the left hand was followed by a better performance of the right hand demonstrating an interhemispheric transfer. The inactivation of the nondominant hemisphere by intracarotid amobarbital injection in aphasic patients is followed by worsening of the verbal performance. This demonstrates the possible compensatory role of the nondominant hemisphere in patients with aphasia. The results are considered to be manifestations of the functional plasticity of the brain.

Adult↗