Effects Of Environmental Enrichment On Sound-azimuth Selectivity Of Neurons In The Auditory Cortex

There have been many studies on the effects of environmental enrichment on brain development and plasticity.Earlier studies in the auditory system have shown that enriched environments sharpen the multi-parametrical responses of neurons in the auditory cortex.However,environmental factors contributing to these cortical changes remain largely unknown.By using rat as a research model,here we investigated the effects of environmental enrichment on behavioral performance in a sound-azimuth discrimination task,and that on sound-azimuth tuning of neurons in the primary auditory cortex.We found that environmental acoustic enrichment(that is,specific acoustic stimuli were added to the enriched environment)significantly improved the performance of rats in the sound-azimuth discrimination task,as shown by increased percent correct and decreased reaction time and azimuth deviation.Further studies showed that both conditions of environmental acoustic enrichment and enriched environments(ie.,no acoustic stimuli were added to the enriched environment)significantly sharpened the sound-azimuth tuning of cortical neurons.This cortical remodeling in spatial tuning was paralleled by increases of cortical parvalbuminlabeled inhibitory inter-neurons.In addition,post-exposure effects of environmental acoustic enrichment were overall larger than that of enriched environments.These findings suggest that the observed sharpening of cortical spatial tuning of cortical neurons presumably contributes to behavioral changes in the sound-azimuth discrimination task induced by environmental acoustic enrichment.They also suggest the critical role of acoustic stimuli in regulating enrichment-induced plasticity of the auditory system,particularly the auditory cortex.These studies have important theoretical and practical significance for understanding of the neural mechanisms underlying the brain plasticity induced by environmental enrichment.