Degraded inferior colliculus responses to complex sounds in prenatally exposed VPA rats

Abstract

Individuals with autism spectrum disorders (ASD) often exhibit altered sensory processing and deficits in language development. Prenatal exposure to valproic acid (VPA) increases the risk for ASD and impairs both receptive and expressive language. Like individuals with ASD, rodents prenatally exposed to VPA exhibit degraded auditory cortical processing and abnormal neural activity to sounds. Disrupted neuronal morphology has been documented in earlier processing areas of the auditory pathway in VPA-exposed rodents, but there are no studies documenting early auditory pathway physiology. Therefore, the objective of this study is to characterize inferior colliculus (IC) responses to different sounds in rats prenatally exposed to VPA compared to saline-exposed rats. In vivo extracellular multiunit recordings from the inferior colliculus were collected in response to tones, speech sounds, and noise burst trains. Our results indicate that the overall response to speech sounds was degraded in VPA-exposed rats compared to saline-exposed controls, but responses to tones and noise burst trains were unaltered. These results are consistent with observations in individuals with autism that neural responses to complex sounds, like speech, are often altered, and lays the foundation for future studies of potential therapeutics to improve auditory processing in the VPA rat model of ASD.