Werner Reichardt Centre for Integrative Neuroscience, and Hertie Institute for Clinical Brain Research, University of Tübingen, Tübingen 72076, Germany.
J Neurosci. 2010 Feb 10;30(6):2060-9. doi: 10.1523/JNEUROSCI.3943-09.2010.
Rats explore environments by sweeping their whiskers across objects and surfaces. Both sensor movement and repetitive sweeping typical for this behavior require that vibrotactile signals are integrated over time. While temporal integration properties of neurons along the whisker somatosensory pathway have been studied extensively, the consequences for behavior are unknown. Here, we investigate the ability of head-fixed rats to integrate information over time for the detection of near-threshold pulsatile deflection sequences applied to a single whisker. Psychometric detection performance was assessed with whisker stimuli composed of different numbers of pulses (1-31) delivered at varying frequencies (10, 20, 100 Hz). Detection performance indeed improved with increasing number and frequency of pulses, albeit this improvement was much lower than predicted by probabilistic combination, suggesting highly sublinear integration of pulses. This behavioral observation was reflected in the firing properties of concomitantly recorded barrel cortex neurons, which showed substantial response adaptation to repetitive whisker deflection. To estimate the integration time with which barrel cortex neuronal activity must be read out to match behavior, we constructed a model monitoring spiking activity of simulated neuronal pools, where spike trains were channeled through a leaky integrator with exponential decay. Detection was accomplished by simple threshold crossings. This simple model gave an excellent match of neurometric and psychometric data at surprisingly small time constants tau of 5-8 ms, thus limiting integration largely to <25 ms. This result carries important implications regarding sensory processing for whisker-mediated perception.
老鼠通过扫过胡须来探测环境中的物体和表面。传感器的运动和这种行为的典型重复性扫动都需要随着时间的推移整合振动触觉信号。虽然已经对触须体感通路中的神经元的时间整合特性进行了广泛研究，但对行为的影响尚不清楚。在这里，我们研究了固定在头部的老鼠在检测施加到单个触须上的近阈脉冲偏斜序列时随时间整合信息的能力。使用由不同数量的脉冲（1-31）以不同频率（10、20、100 Hz）传递的触须刺激来评估心理物理检测性能。检测性能确实随着脉冲数量和频率的增加而提高，尽管这种提高远低于概率组合的预测，这表明脉冲的高度次线性整合。这种行为观察反映在同时记录的桶状皮层神经元的放电特性中，这些神经元对重复性触须偏斜表现出明显的适应。为了估计桶状皮层神经元活动必须读出以匹配行为的整合时间，我们构建了一个模型，监测模拟神经元池的尖峰活动，其中尖峰序列通过具有指数衰减的漏积分器进行传输。通过简单的阈值穿越来完成检测。这个简单的模型在非常小的时间常数 tau 5-8 ms 下，非常好地匹配了神经测量和心理测量数据，从而将整合限制在<25 ms 以内。这个结果对触须介导的感知的感觉处理具有重要意义。
