DYNAMIC REGULATION OF TUNING IN ADULT AUDITORY CORTEX

描述：现已知成人的听觉皮质是 动态监管，而不是传统的观念 生理上是静止的。一个主要的调节因素是习得的行为 声音的重要性。学习改变了对频率的处理 信息并以一种特别强调频率的方式这样做 一种行为获得性的重要刺激。这一结论是基于 人类和动物对此的代谢反应增强的研究结果 刺激，代表刺激的面积增加，以及 细胞对该刺激的频率调谐。这样的调整变化包括 关联性，高度频率专用性，发展迅速和持久 无限期的。因此，听觉皮质的功能组织 反映声音的物理参数及其后天行为 重要性。这种动态调节的机制实际上是 未知。两个主要候选者是(A)前和前的协方差 突触后听觉皮质神经元活动的水平和(B) 乙酰胆碱(ACh)对听觉皮质的神经调节作用 具体地说，在成年豚鼠中，我们将(1)控制突触后 在通过细胞旁的纳米电流呈现音调时的反应 微吸管，(2)刺激核团的双音呈现 听皮层ACh的来源--基底核，(3)阻断胆碱能 听觉皮质在行为学习中的作用，(4)控制 基底核存在时的Tome术中突触后反应 刺激和(5)确定对不同细胞层的影响 听觉皮质。这些研究对健康有着重要的影响。这个 听觉皮质对于正常的感知是必不可少的，尤其是对言语， 这是后天学来的。了解大脑皮层可塑性的机制 简单的刺激，即纯音，构成了进入更大范围的入口点 复杂刺激的大脑皮层处理问题，如语音。 此外，本项目将为理解学习提供基础 聋人和近些年人工耳蜗术后的言语感知 确定了基于学习的时间加工缺陷的补救 阅读困难症。

DESCRIPTION: The auditory cortex in the adult is now known to be dynamically regulated, in contrast to the traditional belief that it is physiologically static. A major regulatory factor is the learned behavioral importance of sound. Learning modifies the processing of frequency information and does so in a way that specifically emphasizes the frequency of a behaviorally acquired important stimulus. This conclusion is based on findings in both humans and animals of increased metabolic response to that stimulus, increased area representing that stimulus and shifts in the frequency tuning of cells to that stimulus. Such tuning changes are associative, highly frequency specific, develop rapidly and last indefinitely. Thus, the functional organization of the auditory cortex reflects both the physical parameters of sound and their acquired behavioral importance. The mechanisms of this dynamic regulation are virtually unknown. Two major candidates are (a) the covariance of pre- and post-synaptic levels of neuronal activity in the auditory cortex and (b) the neuromodulatory action of acetylcholine (ACh) on the auditory cortex. Specifically, in adult guinea pigs, we will (1) control postsynaptic response during tone presentation by nano-currents through a juxtacellular micropipette, (2) pair tone presentation with stimulation of nucleus basalis, the source of ACh to the auditory cortex, (3) block cholinergic actions of the auditory cortex during behavioral learning, (4) control postsynaptic response during tome in the presence of nucleus basalis stimulation and (5) determine the effects on various cell layers of the auditory cortex. The studies have important implications for health. The auditory cortex is essential for normal perception, particularly for speech, which is learned. Understanding the mechanisms of cortical plasticity using simple stimuli, i.e., pure tones, constitutes an entry point into the larger problem of cortical processing of complex stimuli, such as speech sounds. Additionally, this project will provide a basis for understanding learning to perceive speech following cochlear implants in the deaf and recently identified learning-based remediation of temporal processing deficits in dyslexia.