One out of every 150 people in the United States is affected by autism. Autistic individuals are severely impaired in their ability to process the subtle cues used in everyday communication and social interactions. Recent functional imaging studies have revealed serious deficits in speech sound discrimination in both children and adults with autism. The latency increase of speech evoked neural responses is well correlated with the degree of cognitive and language impairments. Unfortunately, the poor resolution of human imaging techniques obscures the neural basis of the impairment. We propose to evaluate speech sound coding in the valproic acid (VPA) animal model of autism, and quantify the beneficial effects of two common autism therapies: auditory training and environmental enrichment. Speech sounds evoke specific spatiotemporal patterns of cell firing in the central auditory system of normal rats.
The first aim of the project is to determine the consequence of VPA exposure on the collicular and cortical representations of speech sounds. Our preliminary results indicate that in utero VPA exposure severely degrades the precise spatiotemporal patterns evoked by speech sounds in auditory cortex. As in autism, the longer latency in our animal model is significantly greater for speech sounds compared to tones.
The second aim of the project is to determine the behavioral consequences of VPA exposure on speech sound discrimination. If the neural spatiotemporal representations of speech sounds are degraded, then it is possible that certain speech sounds may not be distinguishable in VPA treated rats. We therefore predict that speech sound discrimination will be impaired in VPA exposed rats.
The third aim i s to determine the effects of speech training and environmental enrichment on speech evoked activity in VPA exposed rats. Based on previous studies, we predict that both speech training and environmental enrichment will relieve the degradation of the cortical responses to speech sounds and restore speech sound discrimination to control levels in VPA treated rats. The results of the proposed studies will add to our understanding of the neural mechanisms that are associated with speech sound coding. Insights derived from these studies may influence the development of new behavioral and sensory techniques to treat the communication impairments in autism that result in part from degraded speech sound discrimination.

Public Health Relevance

Although individuals with autism are known to have significant communication problems, the neural mechanisms responsible for impaired communication are poorly understood. The proposed animal model for autism will identify a potential cause of speech sound discrimination impairments and quantify the beneficial effects of two common autism therapies: auditory training and environmental enrichment. A better understanding of these mechanisms may aid the design of improved behavioral and sensory therapies to reduce communication impairments in autism.

National Institute of Health (NIH)
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Cognitive Neuroscience Study Section (COG)
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Platt, Christopher
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University of Texas-Dallas
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Engineer, Crystal T; Centanni, Tracy M; Im, Kwok W et al. (2014) Degraded speech sound processing in a rat model of fragile X syndrome. Brain Res 1564:72-84
Engineer, C T; Centanni, T M; Im, K W et al. (2014) Degraded auditory processing in a rat model of autism limits the speech representation in non-primary auditory cortex. Dev Neurobiol 74:972-86
Centanni, T M; Sloan, A M; Reed, A C et al. (2014) Detection and identification of speech sounds using cortical activity patterns. Neuroscience 258:292-306
Reed, Amanda C; Centanni, Tracy M; Borland, Michael S et al. (2014) Behavioral and neural discrimination of speech sounds after moderate or intense noise exposure in rats. Ear Hear 35:e248-61
Hays, Seth A; Khodaparast, Navid; Ruiz, Andrea et al. (2014) The timing and amount of vagus nerve stimulation during rehabilitative training affect poststroke recovery of forelimb strength. Neuroreport 25:676-82
Zhu, Xiaoqing; Wang, Fang; Hu, Huifang et al. (2014) Environmental acoustic enrichment promotes recovery from developmentally degraded auditory cortical processing. J Neurosci 34:5406-15
Engineer, Crystal T; Perez, Claudia A; Carraway, Ryan S et al. (2014) Speech training alters tone frequency tuning in rat primary auditory cortex. Behav Brain Res 258:166-78
Centanni, Tracy M; Chen, Fuyi; Booker, Anne M et al. (2014) Speech sound processing deficits and training-induced neural plasticity in rats with dyslexia gene knockdown. PLoS One 9:e98439
Perez, Claudia A; Engineer, Crystal T; Jakkamsetti, Vikram et al. (2013) Different timescales for the neural coding of consonant and vowel sounds. Cereb Cortex 23:670-83
Centanni, T M; Engineer, C T; Kilgard, M P (2013) Cortical speech-evoked response patterns in multiple auditory fields are correlated with behavioral discrimination ability. J Neurophysiol 110:177-89

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