The long-term objective of this research is to understand how synaptic processing in auditory cortex transforms the neural representation of temporally structured sounds such as music and speech. The focus in this proposal is to test specific hypotheses about how synaptic inhibition transforms the representation of sound from a temporal code into a rate code. This transformation may support multi-sensory integration, because information from sensory areas with different dynamics may need to be converted into a common rate code to be meaningfully combined. The synaptic mechanisms underlying this process remain unknown.
Aim 1 will test whether sustained rate-coded responses in auditory cortex are generated by a stimulus-specific decrease in synaptic inhibition.
Aim 2 will test whether rate-coded responses to periodic stimuli are generated by a stimulus-specific decrease in synaptic inhibition.
Aim 3 will test whether opponent processing of periodic stimuli occurs by a synaptic push-pull mechanism. To accomplish these aims, we will use whole-cell voltage clamp recordings from rat auditory cortical neurons to measure the excitation and inhibition evoked by optimal tones and periodic stimuli. These experiments will help to elucidate the synaptic mechanisms that transform how temporally structured sounds are encoded in auditory cortex. Because temporal structure provides information critical for speech perception, the synaptic processing of time-varying signals in auditory cortex is especially relevant to our understanding of the mechanisms underlying speech processing. The proposed studies will therefore contribute to our basic understanding of the cortical synaptic mechanisms involved in speech perception.
Language-learning impaired children show profound deficits in the processing of temporally structured sound, but specific auditory training can speed up auditory processing in these children and lead to improved speech processing. The proposed studies will provide insight into how the representation of this temporal structure is transformed by synaptic processing in auditory cortex. In the long term, a greater understanding of the mechanisms that contribute to speech processing in auditory cortex will likely influence the development of improved rehabilitation strategies for language impairments.
|Gao, Xiang; Wehr, Michael (2015) A coding transformation for temporally structured sounds within auditory cortical neurons. Neuron 86:292-303|
|Weible, Aldis P; Liu, Christine; Niell, Cristopher M et al. (2014) Auditory cortex is required for fear potentiation of gap detection. J Neurosci 34:15437-45|
|Weible, Aldis P; Moore, Alexandra K; Liu, Christine et al. (2014) Perceptual gap detection is mediated by gap termination responses in auditory cortex. Curr Biol 24:1447-55|
|Kyweriga, Michael; Stewart, Whitney; Wehr, Michael (2014) Neuronal interaural level difference response shifts are level-dependent in the rat auditory cortex. J Neurophysiol 111:930-8|
|Kyweriga, Michael; Stewart, Whitney; Cahill, Carolyn et al. (2014) Synaptic mechanisms underlying interaural level difference selectivity in rat auditory cortex. J Neurophysiol 112:2561-71|
|Moore, Alexandra K; Wehr, Michael (2014) A guide to in vivo single-unit recording from optogenetically identified cortical inhibitory interneurons. J Vis Exp :e51757|
|Moore, Alexandra K; Wehr, Michael (2013) Parvalbumin-expressing inhibitory interneurons in auditory cortex are well-tuned for frequency. J Neurosci 33:13713-23|
|Norman, Madeleine; Tomscha, Katherine; Wehr, Michael (2012) Isoflurane blocks temporary tinnitus. Hear Res 290:64-71|
|Montgomery, Nathan; Wehr, Michael (2010) Auditory cortical neurons convey maximal stimulus-specific information at their best frequency. J Neurosci 30:13362-6|
|Scholl, Ben; Gao, Xiang; Wehr, Michael (2010) Nonoverlapping sets of synapses drive on responses and off responses in auditory cortex. Neuron 65:412-21|