Synaptic mechanisms of coding transformations in auditory cortex

描述(由申请人提供)：这项研究的长期目标是了解听觉皮质中的突触处理如何转换时间结构声音的神经表征，如音乐和语音。这项提议的重点是测试有关突触抑制如何将声音的表征从时间代码转换为速率代码的特定假设。这种转换可能支持多感官整合，因为来自具有不同动态的感官区域的信息可能需要被转换成共同的速率代码才能进行有意义的组合。这一过程背后的突触机制仍不清楚。目标1将测试听觉皮质中持续的速率编码反应是否由刺激特有的突触抑制减少所产生。目标2将测试对周期性刺激的速率编码反应是否由刺激特有的突触抑制减少所产生。目标3将测试对手对周期性刺激的处理是否通过突触推拉机制发生。为了实现这些目标，我们将使用大鼠听皮层神经元的全细胞电压钳记录来测量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，这些机制改变了时间结构的声音在听觉皮质中的编码方式。由于时间结构提供了对语音感知至关重要的信息，因此，听觉皮质中时变信号的突触处理与我们理解语音处理的机制特别相关。因此，拟议的研究将有助于我们对涉及言语知觉的皮质突触机制的基本理解。

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.