Spectro-Temporal Plasticity in Primary Auditory Cortex

描述（申请人提供）：听觉体验可以重塑皮层地图，改变成年动物听觉皮层神经元的感受野特性。这种可塑性的确切形式取决于行为背景和显著声刺激的光谱时间特征。这已经在我们之前的实验中通过结合生理和行为的方法得到了证明，在这些实验中，“在线”光谱时间感受野（strf）与动物行为同时被快速和全面地表征。实验还对比了单细胞在不同听觉任务中STRF的可塑性，使用不同的声音信号控制频谱和时间特征。这些结果与运动和其他感觉系统的适应性可塑性的发现是一致的，并支持了听觉皮层细胞可能在动物从事不同的听觉行为任务时经历快速的、环境依赖的感受野特性变化的假设。这种可塑性可能涉及对底层皮层回路的选择性功能重塑，以塑造最有效的接受区，以完成当前的听觉任务。是什么潜在的机制导致了这种非凡的功能可塑性？本研究的目标是将A1的任务相关可塑性研究扩展到包括言语刺激、新行为范式（区分与识别的对比）在内的各种新任务，探索PEG高阶听觉皮层及其周围区域的可塑性，最后探讨额叶皮层自上而下信号在调节听觉皮层适应性可塑性中的可能作用。我们建议严格检验额叶皮质神经元编码任务规则、期望、目标和声刺激的任务相关意义的假设，并进一步验证当动物执行不同的听觉任务时，来自额叶区域的自上而下影响有助于诱导听觉皮层的快速适应性可塑性，这反映了刺激的性质和任务的目标。我们还将使用平面微电极阵列和层流微电极阵列进行生理实验。我们对听觉和额叶皮层中单个单元和局部场电位的同时神经元记录的初步研究已经带来了令人兴奋的新见解，这可能会在理解扩展神经元网络中产生适应性可塑性的相互作用方面取得进展。

DESCRIPTION (provided by applicant): Auditory experience can reshape cortical maps and transform receptive field properties of neurons in the auditory cortex of the adult animal. The exact form of this plasticity depends on the behavioral context, and the spectrotemporal features of the salient acoustic stimuli. This has been shown by combined physiological and behavioral approaches in our previous experiments in which "on-line" spectrotemporal receptive fields (STRFs) were rapidly and comprehensively characterized simultaneous with the animal behavior. The experiments also contrasted STRF plasticity in single cells across different auditory tasks employing various acoustic signals with controlled spectral and temporal features. These results are consistent with findings of adaptive plasticity in the motor and other sensory systems and support the hypothesis that auditory cortical cells may undergo rapid, context-dependent changes of their receptive field properties when an animal is engaged in different auditory behavioral tasks. This kind of plasticity would likely involve a selective functional reshaping of the underlying cortical circuitry to sculpt the most effective receptive fild for accomplishing the current auditory task. What are the underlying mechanisms that give rise to this extraordinary functional plasticity? The goals of the proposed research are to extend our studies of task-related plasticity in A1 to a variety of new tasks involving speech stimuli, new behavioral paradigms (contrasting discrimination versus recognition), to explore plasticity in the higher order auditory cortical fields of the PEG and surrounding areas, and finally to investigate the possible role of top-down signals from frontal cortex in modulating adaptive plasticity in the auditory cortex. We propose to rigorously test the hypothesis that frontal cortical neurons encode task rules, expectancies, goals and the task-related meaning of acoustic stimuli, and further, that when an animal performs different auditory tasks, top-down influences from frontal areas contribute to the induction of rapid adaptive plasticity in auditory cortex, that reflects boh the nature of the stimuli and goals of the tasks. We shall also conduct our physiological experiments with arrays of planar and laminar microelectrode arrays Our preliminary studies from simultaneous neuronal recordings of single units and local field potentials in auditory and frontal cortex have already lead to exciting new insights, that may lead to progress in understanding the interactions within an extended neuronal network that give rise to adaptive plasticity.