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V Chizhevsky

Publications and source records attributed to V Chizhevsky.

5 recordsLinked to original sources
PubMed1991

The dentate nucleus is a short-latency relay of a primary auditory transmission pathway.

Recordings of unit activity showing 4-6 ms latency responses to a click stimulus provided evidence that the dentate nucleus could function as a short-latency auditory relay. On the basis of these findings, plus fiber fillings from injections of phaseolus leucoagglutinin into the dentate, a new auditory pathway between dorsal and ventral cochlear nuclei, dentate nucleus, and rostral thalamus is proposed. The pathway could provide direct, short-latency transmissions to the motor cortex that bypass the classical auditory receptive cortex.

Acoustic Stimulation↗
PubMed1991

Patterns of unit activity in the rostral thalamus of cats related to short-latency discrimination between different auditory stimuli.

Short-latency auditory-responsive units were found in the rostral thalamus of cats during performance of conditioned eyeblink responses (CRs) elicited discriminatively by a forward-paired, 70-dB-click conditioned stimulus (CS) as opposed to a backward-paired, 70-dB-hiss discriminative stimulus (DS). Discharges in response to the CS or DS were found in 57% of 138 units tested. Forty-one percent of units responding to the CS did so at latencies of less than 40 msec. After conditioning a discriminative CR to click CS, an increase in the ratio of CS-evoked activity to baseline activity was found relative to that before conditioning. This increase was attributable, in part, to a decrease in baseline activity and, in part, to an increase in the magnitude of response to the CS. These responses preceded early components of the electromyographically measured motor responses with latencies sufficient to contribute to initiation of the movement. After acquisition of the CR, the proportion of CS responsive units also increased. We conclude that this area of the thalamus, a region thought to support thalamocortical reverberatory activity, also functions to transmit short-latency auditory signals. Our evidence further suggests that this region may participate in the elicitation of conditioned responses by specific auditory stimuli and in discrimination between auditory stimuli of different significance.

Acoustic Stimulation↗
PubMed1991

Patterns of activity coding discrimination of auditory stimuli differ between mid- and posterolateral thalamus of cats.

The auditory function of units in the mid- (lateralis dorsalis and centrolateral nuclei) and posterolateral (lateralis posterior-pulvinar complex) thalamus of cats was assessed during performance of conditioned eye blink responses (CRs) elicited discriminatively by a forward-paired, 70 dB click conditioned stimulus (CS) as opposed to a backward-paired, 70 dB hiss discriminative stimulus (DS). Discharges in response to the CS or DS were found in over 40% of units tested in each area, with onset latencies as short as 28-32 msec in mid-thalamus and 14 msec in posterolateral thalamus. The results provide evidence that both mid- and posterolateral thalamic regions of cats contain sufficient numbers of auditory responsive neurons to be considered part of the auditory system functionally. Patterns of activity changed after conditioning discriminative responses to the click CS. In mid-thalamus, the ratio of CS-evoked activity to baseline activity increased relative to levels found before conditioning. This increase was attributable to an increase in the magnitude of response to the CS. In posterolateral thalamus, an increase in the signal: noise ratio of activity in response to the CS was also found after conditioning, but this increase depended in large part on a decrease in the rate of baseline firing. Posterolateral thalamic units had substantially higher mean rates of baseline firing than mid-thalamic units before any conditioning sessions were begun.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1990

Oversized, auditory responsive units of rostral, mid, and posterolateral thalamus.

Activity was recorded from 343 units of rostral, mid, and posterolateral thalamus following a conditioned click stimulus (CS). Over 40% of units responded with increased discharge in cats conditioned to blink to the CS. Twenty-nine units with short latency (less than 40 ms) responses were injected intracellularly with phaseolus lectin and identified morphologically; 83% had long, thick primary dendrites with smaller secondary branches. Almost half (46%) had larger somata than the largest previously described thalamic neurons of this morphologic classification. The results suggest that a previously unidentified class of oversized cells is likely to contain many short latency, auditory responsive units. A substantial number of these cells (36%) projected extrathalamically into the internal capsule, and thus may constitute a new auditory pathway between thalamus and cortex.

Acoustic Stimulation↗