Effects of Patterned Sound Deprivation on Short- and Long-Term Plasticity in the Rat Thalamocortical Auditory System In Vivo.

Chloe N Soutar,Simon G Rodier,Laura G Rosen,Hans C Dringenberg

doi:10.1155/2016/3407135

Chloe N Soutar, Simon G Rodier + Show 2 more

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https://doi.org/10.1155/2016/3407135

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Abstract

Postnatal sensory experience plays a significant role in the maturation and synaptic stabilization of sensory cortices, such as the primary auditory cortex (A1). Here, we examined the effects of patterned sound deprivation (by rearing in continuous white noise, WN) during early postnatal life on short- and long-term plasticity of adult male rats using an in vivo preparation (urethane anesthesia). Relative to age-matched control animals reared under unaltered sound conditions, rats raised in WN (from postnatal day 5 to 50–60) showed greater levels of long-term potentiation (LTP) of field potentials in A1 induced by theta-burst stimulation (TBS) of the medial geniculate nucleus (MGN). In contrast, analyses of short-term plasticity using paired-pulse stimulation (interstimulus intervals of 25–1000 ms) did not reveal any significant effects of WN rearing. However, LTP induction resulted in a significant enhancement of paired-pulse depression (PPD) for both rearing conditions. We conclude that patterned sound deprivation during early postnatal life results in the maintenance of heightened, juvenile-like long-term plasticity (LTP) into adulthood. Further, the enhanced PPD following LTP induction provides novel evidence that presynaptic mechanisms contribute to thalamocortical LTP in A1 under in vivo conditions.

Highlights

It is widely recognized that experience-dependent plasticity of sensory systems is greatest during brief, “critical/sensitive” periods of early postnatal life and markedly declines following the closure of these periods [1, 2]
The effects of WN rearing on longterm plasticity in the thalamocortical auditory system of adult rats were examined using long-term plasticity (LTP) induction in vivo
LTP induction resulted in an enhancement of paired-pulse depression (PPD), an effect that was pronounced for WN animals

Summary

Introduction

It is widely recognized that experience-dependent plasticity of sensory systems is greatest during brief, “critical/sensitive” periods of early postnatal life and markedly declines following the closure of these periods [1, 2]. The tonotopic organization of the rodent primary auditory cortex (A1) undergoes rapid, experience-dependent maturation during the first two to three weeks following hearing onset (around postnatal day (PD) 10 in rats) [3]. During this period, the cortical region responsive to tonal stimuli contracts and the juvenile overrepresentation of high frequencies is converted to a mature, more balanced frequency map [4]. The importance of patterned sensory stimulation for cortical maturation is evident in assays that directly assess levels of synaptic plasticity in the thalamocortical auditory system. This work indicates that the experience of patterned acoustic inputs is required for the appropriate development of tonotopy and stabilization of A1 synapses

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