Derdikman Dori, Szwed Marcin, Bagdasarian Knarik, Knutsen Per Magne, Pietr Maciej, Yu Chunxiu, Arieli Amos, Ahissar Ehud
Neurobiology Department, Weizmann Institute of Science, Rehovot, Israel.
Novartis Found Symp. 2006;270:4-14; discussion 14-7, 51-8.
Mammals acquire much of their sensory information by actively moving their sensory organs. Rats, in particular, scan their surrounding environment with their whiskers. This form of active sensing induces specific patterns of temporal encoding of sensory information, which are based on a conversion of space into time via sensor movement. We investigate the ways in which object location is encoded by the whiskers and decoded by the brain. We recorded from first-order neurons located in the trigeminal ganglion (TG) of anaesthetized rats during epochs of artificial whisking induced by electrical stimulation of the facial motor nerve. We found that TG neurons encode the three positional coordinates with different codes. The horizontal coordinate (along the backward-forward axis) is encoded by two encoding schemes, both relying on the firing times of one type of TG neuron, the 'contact cell'. The radial coordinate (from face outward) is encoded primarily by the firing magnitude of another type of TG neurons, the 'pressure cell'. The vertical coordinate (from ground up) is encoded by the identity of activated neurons. The decoding schemes of at least some of these sensory cues, our data suggest, are also active: cortical representations are generated by a thalamic comparison of cortical expectations with incoming sensory data.
哺乳动物通过主动移动其感觉器官来获取大量的感觉信息。特别是大鼠，它们用胡须扫描周围环境。这种主动感知形式会诱导特定的感觉信息时间编码模式，这些模式基于通过传感器运动将空间转换为时间。我们研究了胡须对物体位置进行编码以及大脑对其进行解码的方式。在对面部运动神经进行电刺激诱导的人工胡须运动期间，我们记录了麻醉大鼠三叉神经节（TG）中一阶神经元的活动。我们发现TG神经元用不同的编码方式对三个位置坐标进行编码。水平坐标（沿前后轴）由两种编码方案编码，这两种方案都依赖于一种TG神经元“接触细胞”的放电时间。径向坐标（从面部向外）主要由另一种TG神经元“压力细胞”的放电幅度编码。垂直坐标（从地面向上）由被激活神经元的身份编码。我们的数据表明，至少其中一些感觉线索的解码方案也是主动的：皮层表征是由丘脑将皮层预期与传入感觉数据进行比较而产生的。
