Using the evoked potential technique, studies have been made on localization of the projectional sensory areas in the cerebral cortex (visual, acoustic and somatosensory) of the porpoise T. truncatus. Distribution of these projectional areas in the porpoise is quite different as compared to that in other mammals. Visual and acoustic areas are shifted to the dorsal part of the hemisphere, all the sensory areas investigated exhibit a direct contact with each other.

Animals↗

PubMedDate not supplied

[Mechanisms of orientation selectivity of simple and complex neurons in the visual cortex and a model of the orientation-selective receptive field].

Explore the source record for details and available documents.

Animals↗

PubMedDate not supplied

[Sleep of Caspian seals].

ECoG both hemispheres, EOG, neck EMG, ECG and electrical activity of olfactory bulbs were recorded in 4 free moving adult Caspean seals of both sexes. Their sleep on land and in water was compared. The wakefulness occupied 85,5 +/- 1,5% of total recording time, the slow wave sleep--12,8 +/- 1,4% and paradoxical sleep--1,7 +/- 0,2%. Unlike the dolphins, the Caspean seals possess no unihemispheric slow wave sleep. When the seals sleep on the land or on the water surface and do not change their posture for breathing they may breathe without awakening like the terrestrial mammals. But when the seals emerge or change their posture to get nostrils above the water they wake up briefly for respiration period.

Animals↗

PubMedDate not supplied

[Nonspecific effects on the visual cortex: relationship between the possibility of effect reversal and functional state].

Explore the source record for details and available documents.

Animals↗

PubMedDate not supplied

[Multiple sensory projections in the dolphin cerebral cortex].

The paper presents characteristics of evoked potentials appearing in response to afferent stimuli in the dolphin visual and auditory cortical areas. Both the visual and auditory areas are divided into zones which generate evoked potentials different in form and temporal parameters. They may be regarded as multiple projection zones of the visual and auditory analysers respectively.

Animals↗

PubMedDate not supplied

[Non-specific facilitating influences on the responses of rabbit visual cortex neurons].

A study was made of neuronal responses in the rabbit visual cortex to patterned visual stimuli and their change during non-specific activation reaction. Non-specific activation while only slightly affecting the background neuronal activity, enhances the responses of most units to patterned visual stimuli. A comparison of responses with a different degree of inhibition participation shows that the depression of inhibitory processes may act as a mechanism of facilitation of the responses during non-specific activation. After facilitated responses evoked by the action of the stimulus during non-specific activation, the neurones retain a state of enhanced excitability. Repetition of stimuli not attended with non-specific activation leads to the diminution of excitability. The possible connection of the indicated effects with extinction processes is discussed.

Animals↗