CODING COMPLEX BIOLOGICAL SIGNALS BY THE COORDINATED ACTIVITY OF CORTICAL NEURONS

空间听觉提供了一种强有力的机制， 嘈杂的背景。项目1将探索空间的皮质机制 听觉，首先在安静的环境中，然后在环境噪声中。一个可听见的声音必须 导致大脑皮层的活动分布随时间变化， 在这里被称为声音的“皮层图像”。到 在某种程度上，特定的皮层图像对特定的声音是独特的， 声源可以通过它们的皮层图像来识别。这个项目 将使用多通道记录技术对单个单元活动进行采样 同时在多达32个部位的皮质图像中。背景下 在这种应用中，皮层图像可以被认为是神经元水平的 与MRI、PET和MRI观察到的功能图像相关， 功能性光学成像，在这种情况下具有单细胞空间和1-ms 时间分辨率 特定目标1的目标是识别皮质图像的特征 可以携带与刺激相关的信息。人工神经网络 将被用来确定声源位置的基础上，皮层 反应，识别的准确性将揭示相对 的特定元素可以携带的信息量。 单个神经元和多达32个神经元的集合的反应。 特别研究将给予的相对幅度和时间， 多个单位之间的活动。具体目标2的设计与 项目2研究环境噪声中的空间听觉。的程度 皮层反应的特定元素跟踪行为敏感性， 掩蔽水平将揭示这些特征的相对重要性， 环境噪声中信号检测和鉴别。 听觉皮层是颞叶的关键部分。拟议 一个项目解决了刺激如何在大脑中编码的问题 通过协调神经元群体的活动来控制大脑皮层。研究 声音的皮层图像将补充诊断功能 单神经元水平的成像技术。这项工作应 有助于我们理解感知的神经编码， 颞叶病理学的评估和治疗设计 对伤害和疾病的反应。

Spatial hearing provides a powerful mechanism for discriminating sounds in noisy backgrounds. Project 1 will explore cortical mechanisms of spatial hearing, first in quiet, then in ambient noise. An audible sound must result in a time-varying distribution of activity across the cortex, which will be referred to here as the "cortical image" of that sound. To the extent that specific cortical images are unique to particular sounds, sound sources can be identified by their cortical images. This project will use multi-channel recording techniques to sample single-unit activity within cortical images at up to 32 sites simultaneously. In the context of this application, a cortical image may be regarded as the neuron-level correlate of the functional images that are observed with MRI, PET, and functional optical imaging, in this case with single-cell spatial and 1-ms temporal resolution. The goal of Specific Aim 1 is to identify the features of cortical images that can carry stimulus-related information. Artificial neural networks will be used to identify sound-source locations on the basis of cortical responses, and the accuracy of identification will reveal the relative amount of information that can be carried by particular elements of the responses of single neurons and of ensembles of up to 32 neurons. Particular study will be given to the relative amplitude and timing of activity among multiple units. Specific Aim 2 is designed in parallel with Project 2 to study spatial hearing in ambient noise. The degree to which specific elements of cortical responses track behavioral sensitivity to masker levels will reveal the relative significance of those features for signal detection and discrimination in ambient noise. The auditory cortex is a key element of the temporal lobe. The proposed project addresses the issue of how stimuli might be coded in the cerebral cortex by the coordinated activity of populations of neurons. The studies of the cortical image of a sound will complement diagnostic functional imaging techniques at the level of single neurons. This work should contribute to our understanding of the neural coding of perception, the evaluation of temporal lobe pathology and to the design of therapeutic responses to injury and disease.