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A A Nevskaya

Publications and source records attributed to A A Nevskaya.

5 recordsLinked to original sources
PubMed2005

Separate training of hemispheres to perform visual discrimination in conditions of blocking of interhemisphere transmission by masking.

Subjects were trained to discriminate three figures presented in the left field of vision and three other figures presented in the right field of vision. In these conditions, the two hemispheres usually show identical learning to discriminate the sets of stimuli because the hemispheres in healthy humans can exchange information. In the present study, training was performed in conditions in which, during presentation of stimuli, the opposite visual hemifield was covered by a mask. After training, the recognition of all six figures was compared by presenting them to the left and right visual fields. Each hemisphere recognized figures presented to the cognate hemifield but completely or very nearly failed to recognize figures learned by the other hemisphere. The mask would thus appear to block (completely or partially) the transmission of information from one hemisphere to the other. Thus, it was possible to train the hemispheres separately to recognize different sets of images in healthy subjects.

Discrimination Learning↗
PubMed1991

Hemisphere asymmetry of the visually evoked potentials elicited by gratings of varying spatial frequency.

Visually evoked potentials (VEP) were recorded upon hemifield stimulation with sinusoidal gratings of varying spatial frequency (SF). Recording was bipolar from 0.1-0.2. The gratings were presented randomly in the left, in the right or in both visual hemifields. No systematic VEP asymmetry was observed at low SF. At SFs above 1.5-2 cpd, however, the early wave peaking at about 100 msec after grating onset was usually of greater amplitude when the grating was presented in the left visual field. In previous experiments of our, contrast sensitivity was almost the same in both hemifields. Thus, the VEP data suggest right-hemisphere specialization in processing high SFs and their comparison with the contrast sensitivity data suggests that this specialization occurs at a level higher than stimulus detection or is evident at suprathreshold contrast levels only.

Electroencephalography↗
PubMed1990

Hemisphere asymmetry in the detection of gratings of varying spatial frequency.

Visual field symmetry in contrast sensitivity was investigated under conditions of spatial uncertainty. The stimuli were sinusoidal gratings of varying spatial frequency (SF). They were presented randomly in the left, right or in both visual hemifields. The percent detected gratings were slightly higher than the gratings in the left visual field except for gratings of low SF (0.24-0.48 c/deg). The results suggest the existence of a slight left-field (right-hemisphere) superiority in detecting stimuli of medium and high SF. The asymmetry is too slight to allow any significant difference in the SF-content of the neural representation of the left and right halves of the images; neither might it provide an explanation of some recent data on hemispheric specialization, in particular visual tasks.

Brain↗