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Biomedical subjects

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↗
PubMed1983

[Laminar distribution of current sources in the superior colliculi of the rabbit upon stimulation of the optic nerve].

The evoked potential field in the rabbit superior colliculus was subjected to the current source density analysis to determine the location and sequence of the current sinks and sources after electrical stimulation of the optic nerve. The earliest current sink was observed in the middle part of the stratum griseum superficiale. The later and the most prominent current sinks were observed in the upper part and in the deep part of the stratum griseum superficiale. The time course of the current sinks and sources was in correspondence with the main components of the evoked potential. The results permit indicating the location of afferent synapses and sequence of their activation.

Animals↗
PubMed1981

[Analysis of current source density in the superior colliculi of cats in response to punctate visual stimulation].

The EPs in the cat superior colliculus to the punctiform light stimulation were of negative polarity and did not show the potential reversion. The region of EP recording was from 0.1 to 0.9 mm (stratum griseum superficiale). The field potential profile was subjected to the current source density analysis to determine the location and sequence of the current sources and sinks after punctiform light stimulation. The earliest current sink was observed at the depth 0.6--0.8 mm, the later and the most prominent local one--at 0.2--0.3 mm. The EPs to punctiform light stimuli seem to indicate more precisely the location of afferent synapses.

Animals↗
PubMed1981

[Functional characteristics of visual cortex neurons in the squirrel].

The main functional classes of neurons in the squirrel visual cortex are described. The following classes were revealed on the basis of the receptive field organization and the pattern of response to visual stimuli: direction-non-selective neurons (14%), direction-selective neurons (30%), orientation-selective neurons (49%); 7% of neurons were unclassified. Direction-selective neurons and some non-selective ones were specifically sensitive to high speed of the stimulus movement (hundreds deg/s). Orientation-selective neurons differed in the degree of on- and off-zones overlapping; they may include analogues of simple and complex neurons.

Animals↗
PubMed1981

[Focal evoked potentials in the rabbit visual cortex: density analysis of current sources].

Focal evoked potentials were elicited in the rabbit visual cortex by punctiform light stimuli and analyzed by the current source density technique. They contained two main components. The first component was generated by local sink at depths form 0.6 to 1.0 mm (layer IV) with 30 ms latency and peak time about 50 ms. The second one was generated by less local sink at depths form 0.2-0.3 to 1.3-1.5 mm (layers III-VI) with peak time 90-100 ms. These two sinks are considered as active and indicating the localization of depolarizing synapses. Passive sources are dissipated around the zone of the active sinks.

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↗