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A Ia Supin

Publications and source records attributed to A Ia Supin.

At least 19 recordsLinked to original sources
PubMed1985

[Topical organization of somatic projections to the cerebral cortex of the seal Callorhinus ursius].

Somatotopic projections in the cerebral cortex of the fur seal (Callorhinus ursinus) were determined by microelectrode recordings of the multiple unit activity. Somatosensory cortical area is restricted rostrally by postcruciate and coronal sulci, caudally by anterior suprasylvain sulcus and dorsomedially by ansate sulcus. The somatotopic map in this area is oriented in such a way that the head projection is positioned ventrolaterally and that of the hindlimb dorsomedially. The projection area of the forelimb is immersed in the coronal sulcus. Marked disproportions are observed in the projections of different parts of the soma; the head projection has a relatively large magnification factor and within it the vibrissae are presented with the largest magnification.

Animals↗
PubMed1985

[Color properties of the receptive fields of visual cortex neurons in the squirrel].

The colour-sensitive properties of the visual cortex neurons were studied in the squirrel. All the neurons responded to achromatic, green and blue visual stimuli; responses to red stimuli were slight or absent. According to responses to patterned visual stimuli the neurons were classified as non-selective, directionally-selective and orientation-selective (simple and complex). No colour-opponent properties were revealed in any of these neuronal groups: neuronal responses were qualitatively the same to achromatic, green and blue stimuli, and the receptive fields organization was independent of the stimulus colour. These data are discussed with respect to the fact of presence of colour-opponent cells in the retina and lateral geniculate nucleus of squirrel.

Animals↗
PubMed1979

[Configuration of the electrical field of an evoked potential in in the superiod colliculus of the rabbit brain upon punctiform afferent stimulation].

Evoked potentials were studied in the rabbit superior colliculus to punctiform light stimulation of the receptive field. The evoked potentials were of negative polarity and did not show potential reversion. The depths of recordings were from 0.1 to 1 mM. The 4-6 degrees shift of the punctiform stimulus from the optimal position led to the disappearance of the evoked potential. If large (more than 5-6 degrees) or diffuse stimuli were used the evoked potentials reversed from surface-negative to deep-positive at a depth of 0.3-0.4 mM. It is suggested that the evoked potential to punctiform stimuli indicate more precisely the location of afferent synapses.

Animals↗
PubMed1979

[Squirrel visual cortex neurons selective for contour orientation].

The receptive field organization of orientation-selective neurons was studied in the squirrel visual cortex. Neurons with mutual inhibiting on- and off-areas of the receptive field, partially and completely overlapping excitatory and inhibitory mechanisms were observed. Neurons of the second group are the most typical. They reveal orientation selectivity if the stimuli are in the excitatory area of the receptive field, the inhibitory areas outside the excitatory area sharpen the selectivity. It is supposed that no obvious differentiation between simple and complex neurons exist in the squirrel visual cortex.

Animals↗
PubMed1978

[Neurons of the rabbit visual cortex with simple and complex visual fields].

The receptive filelds of orientation-selective neurons were studied in the rabbit visual cortex. Two mechanisms of the selectivity were found: the mutual inhibition between on- and off-regions of the receptive field (simple type) and the orientation-dependent inhibition within the uniform region of the receptive field. The non-selective neurons could exhibit the lateral inhibition within the uniform region of the receptive field also. It is supposed that both "simple" and "complex" cells originate from the non-selective units.

Animals↗
PubMed1976

[Detemination of the hearing characteristics of the dolphin by the evoked potential method].

The evoked potentials were recorded in the dolphin Tursiops truncatus auditory cortex with implanted electrodes. Thresholds of the responses to sounds (clicks, noises and tones) ranged from 10(-2) to 10(-3) Pa. Noises evoked potentials with the lowest threshold of about 1-10(-3) Pa. The evoked responses were elicited both by on and off sound effects as well as by change of the sound intensity or frequency. The thresholds of responses to changes of intensity were about 0.6-0.8 db (7-10%); those of responses to changes of frequency were about 0.25%. The temporal summation could be observed up to 20 msec.

Animals↗
PubMed1975

[Responses of squirrel visual cortex neurons to patterned visual stimuli].

The responses of visual cortical neurons to patterned visual stimuli were studied in squirrel Sciurus vulgaris. The direction selective, orientation-selective and non-selective neurons were observed. Most direction-selective and non-selective neurons were sensitive to high speeds of stimulus movement--hundreds deg/s. The direction-selective neurons exhibited their selectivity at such high speeds in spite of the short time of the stimulus movement through the receptive field. Orientation-selective neurons (with simple or complex receptive fields) were sensitive to lower speeds of the stimulus movement (tens deg/s). Some mechanisms of the properties described are discussed.

Animals↗
PubMedDate not supplied

[An EEG study of different behavioral states of freely moving dolphins].

ECoG and EMG of neck and eye muscles of four free moving dolphins were recorded during sleep-wakefulness cycle through chronically implanted electrodes. Wakefulness is accompanied by desynchronized ECoG, and slow sleep by synchronized ECoG, including the sleep spindles and theta- and delta-waves. The standard EMG criteria do not allow the discrimination between fast sleep and wakefulness in dolphins. Behavioral observations alone do not inform about dolphin's sleep or wakefulness. The respiration of dolphins may be observed during bilateral ECoG synchronization in slow sleep without arousal. ECoG synchronization as well as desynchronization may be observed when the contralateral eye is open.

Animals↗
PubMedDate not supplied

[The recovery of the reactivity of the auditory system in the dolphin Tursiops truncatus to paired acoustic stimuli with different spectra].

Recovery cycles of the auditory brainstem responses were studied in the bottle-nosed dolphin, Tursiops truncatus, using paired acoustic clicks. The recovery time was longer if both clicks had identical spectra (50% recovery at 0.9 ms), as compared with that of different spectra (50% recovery at 0.35 ms). These results can explain a different recovery time of evoked responses after an artificial sound and after own locating one.

Acoustic Stimulation↗