Latency modulation of collicular neurons induced by electric stimulation of the auditory cortex in Hipposideros pratti: In vivo intracellular recording.

Kang Peng,Jing Wang,Jia Tang,Zi-Ying Fu,Qi-Cai Chen,Yu-Jie Peng,Ming-Jian Yang

doi:10.1371/journal.pone.0184097

Abstract

In the auditory pathway, the inferior colliculus (IC) receives and integrates excitatory and inhibitory inputs from the lower auditory nuclei, contralateral IC, and auditory cortex (AC), and then uploads these inputs to the thalamus and cortex. Meanwhile, the AC modulates the sound signal processing of IC neurons, including their latency (i.e., first-spike latency). Excitatory and inhibitory corticofugal projections to the IC may shorten and prolong the latency of IC neurons, respectively. However, the synaptic mechanisms underlying the corticofugal latency modulation of IC neurons remain unclear. Thus, this study probed these mechanisms via in vivo intracellular recording and acoustic and focal electric stimulation. The AC latency modulation of IC neurons is possibly mediated by pre-spike depolarization duration, pre-spike hyperpolarization duration, and spike onset time. This study suggests an effective strategy for the timing sequence determination of auditory information uploaded to the thalamus and cortex.

Highlights

Sensory modalities should be rapid processed for animals to survive
The auditory information processing of inferior colliculus (IC) neurons depends on the interplay of different excitatory and inhibitory synaptic inputs to the IC
Given that the electric stimulus of the auditory cortex (AC) is earlier than sound stimulus, the electric activation of the corticofugal system from the AC to the IC basically mimics a corticofugal modulatory effect induced by a prior sound stimulation on the responses of IC neurons evoked by subsequent sound stimulation

Summary

Introduction

Sensory modalities should be rapid processed for animals to survive. Previous studies showed that latency contains large amounts of sensory stimulus-related information, including sound location [1], touch location and direction [5,6], light contrast [7], and odor identity [8]. Latency plays an important role in signaling sound source location [1] and can be affected by several sound parameters. The latency of most auditory neurons shortens with increasing sound intensity [9] and discharge spikes locked to the onset of sound [10,11]. The latency of onset response varies with the rise time of sound stimulus and generally shortens as the rise time reduces [1,10]. Latency is tuned to sound frequency, such as having the shortest latency at the center (i.e., best frequency, BF) within the frequencyreceptive field (i.e., frequency tuning curve) and the longest latency at its periphery [4,12]

Methods

Results

Conclusion