Lewis J E, Kristan W B
Department of Biology, University of California, San Diego, La Jolla, California 92093-0357, USA.
J Neurophysiol. 1998 Nov;80(5):2584-92. doi: 10.1152/jn.1998.80.5.2584.
To form accurate representations of the world, sensory systems must accurately encode stimuli in the spike trains of populations of neurons. The nature of such neuronal population codes is beginning to be understood. We characterize the entire sensory system underlying a simple withdrawal reflex in the leech, a bend directed away from the site of a light touch. Our studies show that two different populations of mechanosensory neurons each encode touch information with an accuracy that can more than account for the behavioral output. However, we found that only one of the populations, the P cells, is important for the behavior. The sensory representation of touch location is based on the spike counts in all of the four P cells. Further, fewer than three action potentials in the P cell population, occurring during the first 100 ms of a touch stimulus, may be required to process touch location information to produce the appropriately directed bend.
为了形成对世界的准确表征，感觉系统必须在神经元群体的脉冲序列中准确地编码刺激。这种神经元群体编码的本质正开始被人们所理解。我们对水蛭中一个简单的退缩反射所涉及的整个感觉系统进行了表征，该反射是一种远离轻触部位的弯曲动作。我们的研究表明，两种不同的机械感觉神经元群体各自以一种精度对触觉信息进行编码，这种精度足以解释行为输出。然而，我们发现只有其中一个群体，即P细胞，对该行为很重要。触觉位置的感觉表征基于所有四个P细胞中的脉冲计数。此外，在触觉刺激的最初100毫秒内，P细胞群体中少于三个动作电位可能就足以处理触觉位置信息以产生适当方向的弯曲。
