Characterizing spatial tuning functions of neurons in the auditory cortex of young and aged monkeys: a new perspective on old data.
Characterizing spatial tuning functions of neurons in the auditory cortex of young and aged monkeys: a new perspective on old data.
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DOI：
10.3389/fnagi.2012.00036
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发表时间：
2012
影响因子：
4.8
通讯作者：
Recanzone GH
中科院分区：
文献类型：
--
作者：
Engle JR;Recanzone GH
与听力障碍相关的听力障碍是老年人残疾的主要原因。虽然某些形式的听力缺陷是外周起源的，但其他形式的听力缺陷是中枢介导的。其中一个缺陷是定位声音的能力，这是分离不同声学对象和事件的关键组成部分，这取决于听觉皮层。最近的证据表明，在老年动物的正常锐化初级听觉皮层神经元之间的空间调谐到尾侧场不发生，因为它在年轻的动物。随着年龄的增长，抑制的减少在上升的听觉系统中是常见的，这种空间调谐锐化的缺乏可能是由于在反应的不同时期抑制的减少。也有可能是空间调谐减少的结果，在非最佳位置的抑制减少。在这份报告中，我们发现，老年动物在整个反应期内有更大的活动，但主要是在反应开始期间。这在非最佳方向上最为突出，这与抑制是锐化空间调谐曲线的主要机制的假设一致。我们还注意到，在老年动物中，反应的潜伏期比年轻动物短得多，这与发作前抑制的减少一致。这些结果可以解释的上下文中失败的前馈丘脑-皮层和皮质-皮质电路在老年动物的时间和效率。这种机制，如果在整个皮层区域推广，可能在与年龄相关的认知能力下降中发挥重要作用。
Age-related hearing deficits are a leading cause of disability among the aged. While some forms of hearing deficits are peripheral in origin, others are centrally mediated. One such deficit is the ability to localize sounds, a critical component for segregating different acoustic objects and events, which is dependent on the auditory cortex. Recent evidence indicates that in aged animals the normal sharpening of spatial tuning between neurons in primary auditory cortex to the caudal lateral field does not occur as it does in younger animals. As a decrease in inhibition with aging is common in the ascending auditory system, it is possible that this lack of spatial tuning sharpening is due to a decrease in inhibition at different periods within the response. It is also possible that spatial tuning was decreased as a consequence of reduced inhibition at non-best locations. In this report we found that aged animals had greater activity throughout the response period, but primarily during the onset of the response. This was most prominent at non-best directions, which is consistent with the hypothesis that inhibition is a primary mechanism for sharpening spatial tuning curves. We also noted that in aged animals the latency of the response was much shorter than in younger animals, which is consistent with a decrease in pre-onset inhibition. These results can be interpreted in the context of a failure of the timing and efficiency of feed-forward thalamo-cortical and cortico-cortical circuits in aged animals. Such a mechanism, if generalized across cortical areas, could play a major role in age-related cognitive decline.
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