Effects Of Environmental Acoustic Enrichment On Auditory Cortical Responses Of Rats

It’s well known that an enriched environment(EE) can enhance the plasticity of brain’s function. In this way the capacity of individual’s behavior and perception is strengthened. By using conventional extracellular electrophysiological techniques, we examined impacts of EE on response activity of neurons in the primary auditory cortex (AI) of rats reared in an enriched acoustic environment after birth.1. Early EE exposure enhances responses of neurons in the auditory cortex of ratsUsing conventional electrophysiological techniques, we examined the influence of EE exposure on response properties of rat AI neurons. Rats were either exposed to EE beginning at postnatal day 11 (EE), or reared under normal housing conditions (CON). Recording was then conducted on ～p56 for both rat groups. We found that, when compared with the CON rats, the ability of auditory cortical neurons to follow repetitive stimuli, as measured by the maximal following rate, was increased. In addition, cortical response synchronization was also enhanced after EE rearing. These results show that early EE can enhance responses of neurons in the auditory cortex of rats.2. The EE restores impairments resulted from pulsed noise exposure during the early postnatal periodIn this study, we used conventional extracellular electrophysiological techniques to investigate whether or not EE exposure can restore degraded response capacity of A1 neurons by early pulsed noise exposure. Experimental rats were randomly divided into three groups:(1) NE rats, which were exposed to pulsed noise from P10 to P38, then were returned to a normal environment, and (2) AEE rats, which were exposed to pulsed noise from P10 to P38, then were transferred to EE across the same epoch as that of NE rats. When all these rats reached a certain age of about P66, cortical responses of these rats were recorded and the data were compared with that of control (CON) rats. We found that the response properties of NE rats were degraded when compared with CON rats. For example, there were notable increases of BW20 comparable with CON rats. In addition, the rate following ability of neurons was degraded, as measured by the maximal following rate and response synchronization. EE restored the above deficits such that these properties were now comparable to CON rats. These results show that EE can promote recovery from early noise-induced auditory cortical dysfunction. This study would help us to understand how EE restores the sensory impairment resulted from a disrupted environment during postnatal development.