[The interaction of neurons characterized by a tonic reaction to sound with other neurons in the cat auditory cortex]. / Vzaimodeistvie neironov, kharakterizuiushchikhsia tonicheskoi reaktsiei na zvuk, s drugimi neironami v slukhovoi kore koshki.

Interaction of neurons with tonic response to sound with adjacent or distant (approximately 400-500 micrograms) cortex neurons was studied in acute experiments on 15 immobilized cats using a method of the cross-correlation analysis. A presence of synchronizing excitatory input common for the cells has been revealed in 26 pairs (72%) on the cross-correlograms. The results of the cross-correlation analysis in five pairs of neurons show mono- or polysynaptic excitatory effect of a tonic neuron to impulse activity of another neuron. Negative correlation indicative of the inhibitory influence of tonic neurons on impulse responses of other neurons of the same or adjacent auditory cortex column is revealed in five pairs of neurons, but the inhibitory influences may be considered as monosynaptic ones only in 3 pairs of these neurons (latency of interaction 1.0-1.5 ms). The data obtained permit concluding that the group of neurons characterized by tonic response to sound is a heterogeneous one in the functional respect. An assumption that some neurons of the tonic type are inhibitory interneurons of the auditory cortex, other excitatory ones is under discussion.

[Characteristics of the responses of auditory cortex neurons in the cat to tonal stimulation during nembutal anesthesia and after recovery from it]. / Kharakteristika reaktsii neironov slukhovoi kory koshki na tonal'nuiu stimuliatsiiu vo vremia nembutalovogo narkoza i posle vykhoda iz nego.

Responses of auditory (AI) cortex neurons to tonal (1-25 kHz) stimulation were studied in cats under and after nembutal anaesthesia. Patterns of responses recorded during first hours and 10-30 hours after nembutal injection differed essentially. Most (89%) of neurons of anaesthetized cat had no background activity and produced stereotypical on-responses to tonal stimulation with the best frequency. Off-effects were usually absent. Variability of responses increased substantially after cessation of anesthesia. On-, on-off- and off-responses were obvious in 76% of neurons, approximately 21% of neurons tonically increased or decreased spike activity during the stimulus action. Duration of the stimulus action was reflected in response characteristics of the overwhelming majority of AI cortical neurons.

[Receptive fields of neurons of primary auditory cortex neurons in the cat]. / Retseptivnye polia neironov pervoi slukhovoi oblasti kory mozga koshki.

Receptive fields of primary auditory cortical neurons were investigated by direct stimulation of nerve fibers in different parts of the cochlea in cats anesthetized with nembutal. The size of the excitatory receptive field depends on the location of te neuron in the cortical auditory area. The more caudal is the position of the neuron in the primary auditory cortical projection of the cochlea, the more extended its receptive field is. The most narrow and symmetrical receptive fields were found in the basal coil of the cochlea. A suggestion is made that the region of finest discrimination of acoustic signals is located in the basal coil of the cochlea which has the largest representation in the primary cortex.

[Cochleotopic organization of the primary auditory region of the cerebral cortex in cats]. / Kokhleotopicheskaia organizatsiia pervoi slukhovoi oblasti kory golovnogo mozga koshki.

The cochleotopic organization of the primary auditory cortex (AI) was investigated by means of focal potentials evoked by direct electrical stimulation of the cochlea in cats under nembutal anesthesia. Two foci of maximal activity (dorsal and ventral) which were more prominent in the rostral and medial parts of AI appeared in 85% of animals in response to local stimulation of different cochlear regions. The analysis of the projectional maps shows that different cochlear regions are represented in AI nonproportionally. The basal region is projected to a larger cortical area than both the middle and apical ones. Significant variability was found for cochlear representation in the auditory cortex of different cats.