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N F Podvigin

Publications and source records attributed to N F Podvigin.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

Characteristics of excitation and inhibition of the receptive fields of the retina and lateral geniculate body.

The process of excitation and inhibition in the receptive fields (RF) of the ganglion cells and lateral geniculate body (LGB) of the cat were examined. The extent of the dependence of the magnitude of excitation and inhibition in RF on stimulus intensity was determined. This dependence is a power function with power indices of 0.15--0.20 (LGB) and 0.3--0.5 (retina) for excitation and 0.2--0.3 (LGB) and 0.5--0.6 (retina) for inhibition.

Animals↗
PubMedDate not supplied

Eye movements in the cat evoked by electrical stimulation of the outer geniculate body.

New data were obtained in experiments with unanesthetized animals showing that electrical stimulation of the structures of the outer geniculate body of the cat elicits goal-directed eye movements. Relationships were found between eye-movement amplitude and direction and the position of the eye at the instant of stimulation, as well as the position of the stimulating electrodes in the outer geniculate body. A scheme is proposed for the multilevel interaction of the visual and oculomotor systems during their functioning, and a possible relation is discussed between the described phenomenon and the mechanisms responsible for the foveation of objects during their recognition.

Animals↗
PubMedDate not supplied

The sensitivity of neurons in the lateral geniculate body of the cat to the orientation vectors of brightness gradients.

We describe here a new property of visual neurons: sensitivity to the magnitude and orientation of the brightness gradient vector in a test stimulus presented in the receptive field of the neuron. The brightness gradient test image was a spot (diameter 4 degrees) on the dark background of the slide. Brightness changed linearly within the spot. The absolute value of the brightness gradient varied over the range 0.4-2.7 cd/m2 /degrees in the direction of the brightness gradient. The integral brightness in the test spot containing the gradient image was identical for different values of the brightness gradient. The numbers of spikes in the on- and off-responses of on and off neurons in the lateral geniculate body of cats depended on the orientation of the brightness gradient vector in the test stimulus. The sensitivity of neurons to the orientation of the brightness gradient vector, K (the coefficient of sensitivity), was assessed as the normalized difference between the number of spikes in neuron responses in the preferred and non-preferred orientations of the brightness gradient vector in the neuron's receptive field. The mean sensitivity coefficient for 53 cells was 0.55 +/- 0.20. A 6.7-fold decrease in the brightness gradient resulted in a 3.7-fold decrease in the coefficient of sensitivity (for the preferred direction of the orientation of the gradient vector); there was no change in the latent period of responses. The preferred orientation of the brightness gradient vector in the receptive fields of neurons coincided (to within +/-22.5 degrees) with the radial direction on the map of the field of vision in 45% of cases, and with the tangential direction in 26% of cells.

Animals↗
PubMedDate not supplied

[A model of the regulation of involuntary movements of the eye].

Within the scope of the concepts on the look control mechanism, i. e. the system of interrelated control of head and eye movements a mathematical model is considered which described the control system over eye involuntary movements with quadratic criterion of its work quality. Assuming the optimal character of the control system under study and taking into account the experimental data on the eye movements parameters the relationship between the parameters of the criterion introduced and retinotopic relation of a locus of lateral geniculate is estimated.

Eye Movements↗