Spectro-Temporal Plasticity in Primary Auditory Cortex

描述(由申请人提供)：听觉体验可以重塑成年动物的大脑皮层地图，并改变成年动物听觉皮质神经元的感受场特性。这种可塑性的确切形式取决于行为背景和显著声刺激的频谱时间特征。在我们以前的实验中，结合生理和行为的方法已经证明了这一点，在这些实验中，快速和全面地表征了与动物行为同时进行的在线频谱时间感受野(STRF)。这些实验还对比了单细胞在不同听觉任务中的STRF可塑性，使用了具有受控频谱和时间特征的各种声音信号。这些结果与运动和其他感觉系统的适应性可塑性的发现一致，并支持这样的假设，即当动物参与不同的听觉行为任务时，听觉皮质细胞的接受场特性可能经历快速的、上下文相关的变化。这种可塑性很可能包括选择性地重塑底层皮质回路的功能，以塑造完成当前听觉任务的最有效的接受性文件。产生这种非凡的功能可塑性的潜在机制是什么？这项研究的目标是将我们对A1任务相关可塑性的研究扩展到涉及语音刺激、新的行为范式(对比辨别和再认)的各种新任务，探索PEG及其周围区域高阶听觉皮层区域的可塑性，最后探讨来自额叶皮质的自上而下信号在调节听觉皮质适应性可塑性中的可能作用。我们建议严格检验这一假设，即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，进一步，当动物执行不同的听觉任务时，来自额叶区域的自上而下的影响有助于诱导听觉皮质的快速适应性可塑性，这反映了刺激和任务目标的性质。我们还将用平面和层状微电极阵列进行生理学实验。我们对听觉和额叶皮质单个单位和局部场电位的同步神经元记录的初步研究已经带来了令人兴奋的新见解，这可能有助于理解扩展的神经元网络中产生适应性可塑性的相互作用。

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.