Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Present address: Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.
Nat Neurosci. 2016 Mar;19(3):487-93. doi: 10.1038/nn.4221. Epub 2016 Jan 18.
To attribute spatial meaning to sensory information, the state of the sensory organ must be represented in the nervous system. In the rodent's vibrissal system, the whisking-cycle phase has been identified as a key coordinate, and phase-based representation of touch has been reported in the somatosensory cortex. Where and how phase is extracted in the ascending afferent pathways remains unknown. Using a closed-loop interface in anesthetized rats, we found that whisking phase is already encoded in a frequency- and amplitude-invariant manner by primary vibrissal afferents. We found that, for naturally constrained whisking dynamics, such invariant phase coding could be obtained by tuning each receptor to a restricted kinematic subspace. Invariant phase coding was preserved in the brainstem, where paralemniscal neurons filtered out the slowly evolving offset, whereas lemniscal neurons preserved it. These results demonstrate accurate, perceptually relevant, mechanically based processing at the sensor level.
为了赋予感觉信息以空间意义，感觉器官的状态必须在神经系统中得到表示。在啮齿动物的触须系统中，触须运动周期的相位已被确定为一个关键坐标，并且在体感皮层中已经报道了基于相位的触觉表示。在上升的传入途径中相位是在哪里以及如何被提取的仍然未知。在麻醉大鼠中使用闭环接口，我们发现初级触须传入纤维已经以频率和幅度不变的方式对触须相位进行了编码。我们发现，对于自然受限的触须动力学，通过将每个感受器调谐到受限的运动子空间，可以获得这种不变的相位编码。不变的相位编码在脑干中得以保留，其中副楔内神经元过滤掉缓慢变化的偏移，而楔内神经元则保留了它。这些结果表明在传感器层面进行了准确的、与感知相关的、基于力学的处理。
