CORTICAL REPRESENTATION OF AUDITORY SPACE

临床和动物研究表明，听觉损伤 大脑皮层可能导致声音定位能力的缺陷。 从生理角度解释这些观察结果的努力 未能识别声音位置的皮质表示， 以及以音调组织的初级阶段的当前视图 通向大脑皮层的听觉通路与一个简单的通路不一致- 一对一的听觉空间地图。一个中脑结构，上级 丘脑，确实包含了这样的地图，其中有声音的位置 源由单个焦点的位置表示 最大限度地激活神经元，令人费解的是，类似的地图 在大脑皮层中还没有被描述。一种可能性是， 上丘的听觉地形图是 感觉运动整合发生在丘脑和， 因此，是该结构所独有的。在大脑皮层中， 声音可以由以下特征模式来表示 包含多个活动区而不是单个焦点的激活 活跃度。另一种可能性是听觉空间是 映射到大脑皮层，但之前寻找它的努力主要集中在 在错误的皮质区域或使用了不适当的 刺激物。拟议的实验将使用宽带刺激 在自由声场中呈现，以表征 与特定部位相关的皮质活动。特例 将注意到大部分未被探索的非调性主题 区域，包括第二听觉区域(A2)，它表现为 先验是最有可能包含空间的区域 代表权。这些实验的结果将表明 听觉空间在大脑皮层中是否由一对一的 一张空间地图或通过其他更分散的模式 活动。 听觉皮质是颞叶的一个关键元素，它 本身就是许多交流过程的大脑皮层基质。 对听觉皮质功能组织的理解 可能导致诊断程序的开发 对颞叶病理的评价。听觉空间 在这一意义上，表述特别相关，因为来源 位置是声音的为数不多的基本特征之一 显然，双方都没有代表。在更广泛的范围内， 拟议的研究将有助于对 大脑皮质功能，这是发育所必需的 对脑损伤和疾病做出适当的治疗反应。

Clinical and animal studies indicate that lesions of the auditory cortex can result in deficits in the ability to localize a sound. Efforts to account for these observations in physiological terms have failed to identify a cortical representation of sound location, and the current view of the tonotopically organized primary auditory pathway to the cortex is inconsistent with a simple one- to-one map of auditory space. A midbrain structure, the superior colliculus, does contain such map in which the location of a sound source is represented by the position of a single focus of maximally activated neurons, and it is puzzling that a similar map has not been described in the cortex. One possibility is that the auditory map in the superior colliculus is a product of the sensorimotor integration which takes place in the colliculus and, thus, is unique to that structure. In the cortex, the location of a sound might be represented by characteristic patterns of activation comprising multiple active areas rather than single foci of activity. An alternative possibility is that auditory space is mapped in the cortex, but previous efforts to find it have focused on the wrong areas of the cortex or have used inappropriate stimuli. The proposed experiments will use broad band stimuli presented in a free sound field to characterize the patterns of cortical activity associated with specific locations. Particular attention will be given to the largely-unexplored non-tonotopic areas, including the second auditory area (A2), which appear a priori to be the most likely areas to contain a spatial representation. Results of these experiments will indicate whether auditory space is represented in the cortex by a one-to- one map of space or by some other, more distributed, pattern of activity. The auditory cortex is a key element of the temporal lobe, which is itself the cortical substrate for many communicative processes. An understanding of functional organization in the auditory cortex could lead to the development of diagnostic procedures for evaluation of temporal lobe pathology. Auditory spatial representation is particularly relevant in that sense, since source location is one of the few basic features of a sound which apparently is not represented bilaterally. On a broader scale, the proposed research will contribute to the basic understanding of cortical function which is essential for the development of appropriate therapeutic responses to brain injury and disease.