CORTICAL MECHANISMS OF AUDITORY PERCEPTION AND MEMORY

听觉和记忆的皮质机制

• 批准号: 6162850
• 负责人: M MISHKIN
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF MENTAL HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6162850
• 关键词: Macaca mulatta; auditory cortex; auditory discrimination; behavioral /social science research tag; brain mapping; experimental brain lesion; memory; neural information processing; sound frequency

Speech and language in the developing child are so prepotent and resilient that their acquisition is precluded by brain damage only if it affects the perisylvian region bilaterally. Recently, we reported on a child ("Alex") who failed to develop speech and language, in this case because of epilepsy associated with Sturge-Weber disease, a congenital anomaly affecting the blood supply to his left hemisphere. However, at the age of nearly nine and a half, having received a left hemispherectomy for relief of epilepsy ten months earlier, and having had all anticonvulsants withdrawn three months earlier, Alex suddenly began to acquire speech and language for the first time, presumably because his right hemisphere had now been released from functional interference. His early progress resembled that of a normal 1 to 3-year-old child, first producing words, then word combinations, and finally, grammatical phrases, although he accomplished this in about nine months instead of the usual eighteen. Now 16 years old, having improved progressively in both language and other cognitive functions since his speech onset, he performs these functions at a level equivalent to that of an 8 to 10-year-old. Moreover, comparison of his receptive and expressive language ability, memory, and intelligence with those of other left or right hemispherectomized children with early onset of disease, but with early development of speech and language, indicate that, despite his late start, Alex has suffered no permanent disadvantage relative to the others. His case is remarkable in showing just how long the complex neural system underlying linguistic function, and one limited moreover to an isolated right hemisphere, can remain viable despite disuse from birth onward. The results in Alex, as in other children with left hemispherectomy, reemphasize the fact that although speech and language are uniquely human, the uniqueness does not reside in some nonreplicable capacity of the human left hemisphere. This project thus seeks to explore the functional organization of the auditory cortex of rhesus monkeys using physiological, anatomical, and behavioral techniques. Our first such study confirmed that neurons in the rostral area (R) of the supratemporal plane respond preferentially to low-frequency tones, whereas neurons in the caudo-medial area (CM) of the supratemporal plane prefer high frequencies. Subsequent lesion and anatomical tracing experiments have provided convergent evidence that area CM, unlike area R, depends on tonotopic input from primary auditory cortex (AI), which lies between the CM and R. Area R, on the other hand, like A1, appears to receive tonotopic input directly from the ventral division of the medial geniculate body. In the lateral belt areas of auditory cortex, which receive input from both R and AI, most neurons do not respond well to pure tones. However, we have found that units in this region can be driven briskly by bandpass-filtered noise (BPN) bursts. Using this new type of stimulus, cochleotopic maps were revealed along the antero-posterior axis in three lateral areas, which we have termed AL, ML, and CL. The neurons here are tuned to a best center frequency of the BPN bursts, a dimension that is represented along the rostro-caudal axis. They are also tuned to a best bandwidth of these bursts, which is represented orthogonally to best center frequency, i.e. along the medio-lateral axis. Finally, these neurons also respond well to frequency-modulated (FM) sounds and show selectivity for the rate and direction of FM stimuli. Noise bursts and FM sounds are essential components of many species-specific communication calls, and some neurons in the lateral belt areas respond selectively to such calls. Post-mapping injections of tracers into the three tonotopic areas of the lateral belt (AL, ML, and CL) have revealed distinctive patterns of thalamic projections from the medial geniculate, supraorbital, medial pulvinar, and medial dorsal nuclei. The three tonotopic areas project, in turn, to numerous other cortical regions, including the anterior superior temporal gyrus, the parietal lobe, the anterior cingulate gyrus, and five different regions within the prefrontal cortex. Results of the anatomical tracing experiments will help guide our future electrophysiological and lesion studies in monkeys trained on behavioral tasks. The lesion studies have been initiated and have yielded a surprising preliminary finding, namely, combined perirhinal and entorhinal ablation of a type that produces severe impairment in both visual and tactile recognition appears to have little or no effect on auditory recognition. Experiments are currently underway to determine whether this unexpected difference in behavioral effects is due to differences in training techniques (other than the sensory modality being tested) or to a genuine difference in the neural substrate for auditory as compared with visual and tactile memory.

发育中的孩子的言语和语言是如此的实力，并且 只有在脑部损害的情况下，他们的收购才能使他们的收购被排除 双侧影响Perisylvian区域。 最近，我们报道了 在这种情况下未能发展语音和语言的孩子（“ Alex”） 由于癫痫与Sturge-weber疾病有关，先天性 异常影响他左半球的血液供应。 但是，在 近9岁的年龄已经左 半胸切除术以缓解十个月前的癫痫病，并具有 三个月前所有抗惊厥药都撤回了，亚历克斯突然 大概是第一次开始获取言语和语言，大概是 因为他的右半球现在已经从功能上释放 干涉。 他的早期进展类似于普通1的进度 3岁的孩子，首先产生单词，然后是单词组合，以及 最后，语法短语，尽管他在 九个月而不是通常的18个月。 现在16岁，有 在语言和其他认知功能方面逐渐改善 自从演讲发作以来，他以某个级别执行这些功能 相当于8至10岁的年龄。 而且，对他的比较 接受和表现力的语言能力，记忆和智力 其他左右半球切除术的儿童 疾病的发作，但随着言语和语言的早期发展， 表明尽管他迟到了，但亚历克斯没有永久性 相对于其他人的劣势。 他的案子非常出色 语言功能的基础复杂神经系统多长时间， 而且一个有限的右半球有限 尽管从出生开始，但可行。 Alex的结果，如 其他有左半胸切除术的儿童，重新强调了一个事实 尽管言语和语言是独特的人类，但独特性并不是 驻留于人类左半球的某种不可替代的能力。 因此，该项目试图探索 恒河猴的听觉皮层使用生理，解剖学和 行为技术。 我们的第一项研究证实了神经元中的神经元 颞上空的延髓区域（R）优先响应 低频音调，而神经元的神经元（CM）的神经元 超时面更喜欢高频。 随后的病变和 解剖学追踪实验提供了收敛的证据表明 与区域R不同的区域CM取决于主要听觉的调子输入 位于CM和R.区域R之间的皮层（AI） 像A1一样的手似乎直接从 内侧遗传体的腹侧分裂。 在听觉皮层的外侧皮带区域，从 R和AI，大多数神经元对纯色调的反应不佳。 然而， 我们发现，该地区的单位可以轻快地驱动 带通滤波噪声（BPN）爆发。 使用这种新型的刺激， 沿着前后轴揭示了三个前后轴的耳蜗图 我们称为AL，ML和CL的横向区域。 这里的神经元 被调整为BPN爆发的最佳中心频率，一个维度 沿着rostro-caudal轴表示。 他们也被调到 这些爆发的最佳带宽，与 最佳中心频率，即沿Medio层轴。 最后， 这些神经元对频率调节（FM）的声音也有很好的反应 显示FM刺激速率和方向的选择性。 噪音爆发 FM声音是许多特定物种的重要组成部分 通话通话，侧带区域的一些神经元反应 选择性地对这样的呼叫。 绘图片的映射后注射到该区域的三个吨位区域 侧带（AL，ML和CL）已揭示了独特的模式 内侧，上部，内侧的丘脑投影 pulvinar和内侧背核。 三个吨位区域项目， 反过来，到包括前部在内的许多其他皮质区域 上颞回，顶叶，前扣带回 回，前额叶皮层内的五个不同区域。 结果 解剖学追踪实验将有助于指导我们的未来 对行为训练的猴子的电生理和病变研究 任务。 病变研究已开始并产生 令人惊讶的初步发现，即周围和 两者都会产生严重损害的类型的肠道消融 视觉和触觉识别似乎对 听觉识别。 目前正在进行实验以确定 行为影响的意外差异是否归因于 训练技术的差异（感觉方式除外 被测试）或在神经基板上的真实差异 听觉与视觉和触觉记忆相比。