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S V Medvedev

Publications and source records attributed to S V Medvedev.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Role of neurons of the thalamus and striopallidar complex of the human brain in ensuring the constancy of visual perception].

The neuronal impulse activity during visual testing for orientation sensitivity in different head tilts was recorded in parkinsonian++ patients diagnosed and treated with long-term intracerebral electrodes implanted into different nuclei of the thalamus and striopallidar complex. It was revealed that some neuronal populations responded only to the definite orientation of the stimuli. The "preferable" orientations were not changed for the most orientation-selective neurons during left and right head positions differing by 90 degrees.

Electrodes, Implanted↗
PubMed1987

[Selectivity of the neuronal responses of the human brain to different angular orientations of visual stimuli].

In parkinsonic patients with long-term intracerebral electrodes implanted into different nuclei of the thalamus and striopallidar complex the neuronal impulse activity was recorded during visual testing for orientation sensitivity. Visual testing revealed significant responses in multiple unit activity of studied neuronal populations to the angular orientations of the presented stimuli differing from background stimulus orientation. This responses were spatially specific and were not the result of modulation of the activity of these units by the common afferent signal. Neuronal populations differently responding to stimuli which differ only in the angular orientation were observed. These findings might be interpreted as an orientation sensitivity. Such orientation sensitivity of various units differs both in optimal orientation angle and sharpness of responses, some unit groups responding to the definite orientation of the stimuli only. It is suggested that the neuronal populations with significant responses to the visual stimuli used are the elements of thalamostriopallidar system which plays an important role in the maintenance of motor functions. The convergence of motor and visual information within this system probably enables their comparison and interaction, related to the visual perception constancy.

Brain Mapping↗
PubMed1984

[Relationships of distantly located neuronal populations in the human brain in the realization of the thinking process].

The time characteristics of the interneuronal connections as well as interrelationships among distant neuronal populations of the human brain deep structures were studied during monotonous mental activity. It was shown that stable interrelationships could be considered as a correlate of mental activity though the connections themselves were not of the correlative nature. These connections, being the elements of the activity--maintaining system, could be of various degree of rigidity.

Brain↗
PubMedDate not supplied

A study of the connectedness among distant neuronal populations in the human brain during mental activity.

In this article, we present the results of a study of connectedness among distant neuronal populations in human deep-brain structures. The time characteristics involved and the stability of the connections between different neuronal populations during monotonous mental activity are discussed. We show that a stable connectedness does correlate with mental activity; however, the connections themselves do not correlate with one another. We also show that the individual connections, the elements of the system which make mental activity possible, can function with various degrees of rigidity or flexibility.

Brain Mapping↗
PubMedDate not supplied

[New criteria for positron emission tomographic diagnosis of brain glioma using 11C-methionine].

The study was based on the data of positron emission tomography (PET) and L-[methyl]-[11C]-methionine used in 117 patients with suspected brain tumor. PET data on 74 patients with histologically verified cerebral tumors were analyzed in detail. New additional criteria for assessing PET scans, which formed the PET syndromes of astrocytomas, anaplastic astrocytomas, and glioblastomas. Operative and histological verification confirmed the high validity of the proposed criteria for defining the type of a tumor.

Adolescent↗