Synaptic mechanisms of coding transformations in auditory cortex

描述（由申请人提供）：本研究的长期目标是了解听觉皮层中的突触处理如何转换时间结构化声音（如音乐和语音）的神经表征。在这个建议的重点是测试特定的假设，突触抑制如何将声音的表示从时间代码转换为速率代码。这种转换可以支持多感觉整合，因为来自具有不同动态的感觉区域的信息可能需要被转换成共同的速率代码以被有意义地组合。这一过程背后的突触机制仍然未知。目的1将测试听觉皮层中持续的速率编码反应是否由突触抑制的刺激特异性降低产生。目标2将测试对周期性刺激的速率编码反应是否由突触抑制的刺激特异性降低产生。目标3将测试是否对手处理周期性刺激发生的突触推拉机制。为了实现这些目标，我们将使用大鼠听觉皮层神经元的全细胞电压钳记录来测量由最佳音调和周期性刺激引起的兴奋和抑制。这些实验将有助于阐明突触机制，转换如何在听觉皮层编码的时间结构的声音。由于时间结构提供了言语感知的关键信息，听觉皮层中时变信号的突触处理与我们理解言语处理的机制特别相关。因此，拟议中的研究将有助于我们的基本了解皮层突触机制参与言语知觉。 公共卫生相关性：学龄前学习障碍儿童在时间结构声音的处理方面表现出严重的缺陷，但特定的听觉训练可以加快这些儿童的听觉处理，并改善语音处理。这些研究将有助于我们深入了解听觉皮层的突触加工是如何改变这种时间结构的。从长远来看，更好地理解听觉皮层中的语音处理机制可能会影响语言障碍康复策略的改进。

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: 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.