Stimulus-dependent oscillations and evoked potentials in chinchilla auditory cortex

Abstract

Besides the intensity and frequency of an auditory stimulus, the length of time that precedes the stimulation is an important factor that determines the magnitude of early evoked neural responses in the auditory cortex. Here we used chinchillas to demonstrate that the length of the silent period before the presentation of an auditory stimulus is a critical factor that modifies late oscillatory responses in the auditory cortex. We used tetrodes to record local-field potential (LFP) signals from the left auditory cortex of ten animals while they were stimulated with clicks, tones or noise bursts delivered at different rates and intensity levels. We found that the incidence of oscillatory activity in the auditory cortex of anesthetized chinchillas is dependent on the period of silence before stimulation and on the intensity of the auditory stimulus. In 62.5% of the recordings sites we found stimulus-related oscillations at around 8-20 Hz. Stimulus-induced oscillations were largest and consistent when stimuli were preceded by 5 s of silence and they were absent when preceded by less than 500 ms of silence. These results demonstrate that the period of silence preceding the stimulus presentation and the stimulus intensity are critical factors for the presence of these oscillations.

Induced cortical responses require developmental sensory experience

“…The present data are consistent with previous analyses of evoked and induced responses in the auditory system with the similar structure of time-frequency responses ( Delano et al , 2008 ; Steinschneider et al , 2008 ; Nourski et al , 2014 ). While auditory evoked and induced response has been well described in normal hearing subjects ( Tallon-Baudry and Bertrand, 1999 ; Trautner et al , 2006 ; Fujioka et al , 2009 ; Sedley et al , 2016 ) and observed also in postlingual cochlear implant users ( Agrawal et al , 2013 ; Senkowski et al , 2014 ), consequences of congenital deafness on this activity have remained unknown so far.…”

A frequency peak at 3.1 kHz obtained from the spectral analysis of the cochlear implant electrocochleography noise

“…ÓLeary et al, 2023). From animal studies, it is known that the evoked potential analysis methods can eliminate important information from the single-trial frequency domain that is not time-locked to the synchronizing stimuli (Delano et al, 2008; Yusuf et al, 2017). In our experiments, we found that the cochlear microphonic responses (to the 0.5 and 2 kHz stimuli) of the same data were larger when evaluated with evoked methods than with induced methods.…”

Respuestas cerebrales al silencio: hacia una nueva forma de evaluación clínica de la audición

“…Estudios en modelos de roedores (ratas y chinchillas) han mostrado la presencia de oscilaciones de baja frecuencia en la corteza auditiva (bandas theta, alfa y beta [< 20 Hz]), que aparecen luego de periodos de silencio y que disminuyen la amplitud de las respuestas a estímulos auditivos [33][34][35] (Figura 3). Este tipo de respuestas cerebrales amplifica la primera respuesta a un estímulo auditivo que rompe el estado de silencio.…”

“…Estos ejem- Estímulos auditivos no precedidos de silencios prolongados provocan respuestas evocadas en la corteza auditiva sin oscilaciones posteriores (imagen inferior). Figura modificada de Délano y cols., 2008 33 .…”