CORTICAL PLASTICITY AND PROCESSING OF COMPLEX STIMULI

从神经科学对皮质可塑性的研究中得出的见解在制定一些神经疾病的治疗策略方面是不可或缺的，包括阅读困难、耳鸣和中风。然而，由于这些研究大多集中在相对简单的感觉刺激上，我们对塑造更复杂刺激(如言语)皮质表征的可塑性原理的理解仍然处于初级阶段。拟议的实验记录了依赖经验的可塑性如何改善听觉皮质对光谱时间复杂刺激的表征，并通过促进我们对参与语言学习的大脑机制的理解，将有助于治疗交际障碍。使用简单的刺激，我们已经证明了电刺激胆碱能基底核(NB)产生与自然学习平行的强大的皮质可塑性。拟议的实验将通过将NB刺激与复杂的光谱时间刺激配对来扩展这一系列。两种不同的编码策略，已经证明刺激胆碱能核基(NB)产生与自然学习平行的强大的皮质可塑性。拟议的实验将通过将NB刺激与复杂的光谱时间刺激配对来扩展这一系列。有两种不同的策略被提出来代表记忆的神经基础，它们伴随着对行为重要的复杂刺激的自然学习而出现。在第一种方法中，复杂的特征用神经元的分布活动来表示(粗编码)；而在第二种方法中，复杂的刺激用专门的过滤器来表示，以适应特定的光谱时间转换(稀疏编码)。我们的初步证据表明，NB刺激导致了表征可塑性，这种可塑性结合了两种编码策略。除了增强光谱和时间反应外，NB的激活与光谱时间序列配对产生了组合的选择性神经反应，这在幼稚的皮质中不存在。这些结果表明，组合的选择性并不局限于物种/特定的发声，以及声环境的表现。我们继续的研究将检查其他几个声刺激，以准确地确定需要什么刺激特征来产生我们初步结果中观察到的表征可塑性的每个元素。

The insights derived from neuroscience studies of cortical plasticity have been indispensable in the development of treatment strategies for a number of neurological disorders, including dyslexia, tinnitus, and stroke. However, because most of these studies were focused on relatively simple sensory stimuli, our understanding of the plasticity principles that shape the cortical representation of more complex stimuli, such as speech, remains rudimentary. The proposed experiments document how experience-dependent plasticity improves the auditory cortex representation of spectro temporally complex stimuli and, by advancing our understanding of brain mechanisms involved in the learning of language, will aid in the treatment of communicative disorders. Using simple stimuli, we have demonstrated that electrical stimulation of the cholinergic nucleus basalis (NB) generates robust cortical plasticity that parallels natural learning. The proposed experiments will extend this series by pairing NB stimulation with complex spectrotemporal stimuli. Two different coding strategies, which have demonstrated stimulation of the cholinergic nucleus basis (NB) generates robust cortical plasticity that parallels natural learning. The proposed experiments will extend this series by pairing NB stimulation with complex spectrotemporal stimuli. Two different strategies, which have been proposed to represent the neural basis of memory, emerge with natural learning of behaviorally important complexes stimuli. In the first, complex features are represented by the distributed activity of neurons (coarse coding); while in the second, complex stimuli are represented with specialized filters tuned to specific spectrotemporal transitions (sparse coding). Our preliminary evidences indicates that NB-stimulation leads to representational plasticity that combines both coding strategies. In addition to sharpening spectral and temporal responses generally, NB activation paired with a spectrotemporal sequence created combination selective neural responses that do not exist in naive cortex. These results demonstrate that combination selectivity is not limited to species/specific vocalizations, and representations of the acoustic environment. Our continuing studies will examine several other acoustic stimuli to determine precisely what stimulus features are required to generate each element of representational plasticity observed in our preliminary results.