Evoked responses to electrical stimulation of the auditory pathway during the wake/sleep cycle

doi:10.1016/0006-8993(71)90490-2

Brain Research

Volume 35, Issue 2, 24 December 1971, Pages 491-500

https://doi.org/10.1016/0006-8993(71)90490-2 Get rights and content

Abstract

Cats with chronically implanted electrodes were used to study changes in the auditory pathway during the wake/sleep cycle. Evoked responses to electrical stimulation of brain stem and thalamic nuclei were recorded and the animals' state of arousal was determined by observation and by monitoring EEG and EMG. Evoked responses in superior olive and inferior colliculus were invariant during the wake/sleep cycle. Evoked responses in medial geniculate and auditory radiations showed significant changes in slow wave sleep compared with wakefulness when stimulated from nuclei below inferior colliculus. However, with inferior colliculus stimulation, no significant changes in response at medial geniculate or radiations were observed. Evoked responses recorded from posterior A1 cortical sites showed increased amplitude of the late wave and simplification of the early biphasic waves during slow wave sleep. In contrast, evoked responses recorded from Ep and anterior A1 sites decreased in amplitude or were absent during slow wave sleep compared to responses recorded during wakefulness. No significant differences between evoked responses recorded at cortex during wake or REM sleep were obtained. It is suggested that in the auditory system, the major changes occurring during the wake/sleep cycle are cortical in origin, and sub-areas of auditory cortex change differentially. Some change is also observed in medial geniculate only if stimulation is below the level of inferior colliculus.

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Cited by (4)

Intensity dependence of auditory evoked potentials in behaving cats
1996, Electroencephalography and Clinical Neurophysiology - Evoked Potentials
The intensity dependence of auditory evoked potentials (AEPs) recorded epidurally over the primary (AI) and secondary (AII) areas of the auditory cortex was studied in behaving cats during wakefulness, sleep and anesthesia. Four kHz tones of 50, 60, 70, and 80 dB SPL, presented in random order every 2 ± 0.2 s by a bone conductor, elicited clear changes of the AEP amplitudes with increasing stimulus intensity, but individual components displayed different responses curves. AEP components from the AI region showed saturation of their amplitude with stimulus intensity (P13, P34) or no amplitude increase (N19), while amplitude and intensity were linearly related in the AII area. The intensity dependence of the first positive component (P12/P13) was consistently stronger for the AEP recorded from the AI than from the AII area, while later components exhibited no difference between AI and AII. During slow wave sleep, the intensity dependence of this first positive component increased in the two areas, while that of later components decreased. Pentobarbital anesthesia abolished almost all later components and depressed the intensity dependence of the first positive component both in the AI and AII area. These results indicate that (1) clear intensity dependence of AEP exists in the cat auditory cortex and (2) this intensity dependence, especially that of the first positive AEP component, shares functional similarities to the human augmenting/reducing phenomenon in the auditory modality concerning regional differences and sleep-waking cycle.
Modulation of auditory cortex unit activity during the performance of a conditioned response
1978, Experimental Neurology
Single-unit activity in primary auditory cortex was studied in unanesthetized, paralyzed cats during the performance of a classical conditioning task. The conditioned stimulus was a 0.5-s white noise (WN) burst paired with tail shock delivered 4.5 s later. Cats habituated to WN without shock served as controls. Overlayed on these tasks was a continuous background of $1 s$ , behaviorally irrelevant, 100-ms duration tone bursts set to the best frequency and optimal intensity for the particular unit being studied. Spontaneous activity and tone responses following WN were compared with the respective activity preceding WN. The spontaneous or evoked activity of 75% of the cells recorded in the trained animals changed significantly after WN, whereas the activity of 28% of the cells recorded in habituated animals changed. Augmentation and suppression of both spontaneous and evoked activity were found. These results have implications for the encoding of acoustic stimuli in terms of the modulation of lemniscal sensory system activity.
Changes in unit responses to tones after food reinforcement in the auditory pathway of the rat: Intertrial arousal
1978, Experimental Neurology
Experiments were carried out to determine the effects of short-term changes in behavioral arousal on the responsiveness to auditory stimuli of medial geniculate and inferior colliculus neurons in the rat. The independent variable was the time of presentation of the signals after a food pellet, the assumption being that the animal's state of arousal might vary after a consummatory act, and that this fact in turn might modify unit activity. Eight different periods were tested in a random order of presentation, the periods varying between 20 and 180 s from the time of presentation of a food reward. The findings indicate increased responsiveness after long intervals, as measured in peak response firing rate, together with decreased spontaneous rate in a 200-ms period before the auditory signals (background rate). The results demonstrate that variations in arousal during the short periods between food rewards in the paradigm tested influence both the spontaneous rate of discharge and the responsiveness of auditory neurons to sensory input, but that the pattern of changes is different in the medial geniculate and in the inferior colliculus. These variations are of a short-term nature compared with the long-term variations that have come to be expected with changes in the motivational or sleep-wake state of the animal. Recognition of this type of modulating influence is of great importance to neurophysiological studies of learning, in view of the fact that associative neural changes have to be extracted from the nonassociative changes that occur simultaneously.
Intranuclear rods and sheets in rat cochlear nucleus
1972, Journal of Neurocytology

^*: Present address: Department of Psychology, University of Chicago, Chicago, Ill. 60637.

^**: Present address: Division of Neurology, University of California at Irvine, Irvine, Calif. 92664

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Evoked responses to electrical stimulation of the auditory pathway during the wake/sleep cycle

Abstract

Electroenceph. clin. Neurophysiol.

Exp. Neurol.

Exp. Neurol.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Reflex response to clicks of cat's tensor tympani during sleep and wakefulness and the influence thereon of the auditory cortex

Arch. ital. Biol.

Changes in the auditory input of wakefulness and during the synchronized and desynchronized stages of sleep

Arch. ital. Biol.

Changes in click-evoked responses in the auditory system and the cerebellum of free moving cats during sleep and waking

Arch. ital. Biol.