Simulation of motion on the skin. V. Effect of stimulus temporal frequency on the representation of moving bar patterns in primary somatosensory cortex of monkeys.
Simulation of motion on the skin. V. Effect of stimulus temporal frequency on the representation of moving bar patterns in primary somatosensory cortex of monkeys.
复制标题
模拟皮肤上的运动。
DOI：
10.1152/jn.1992.67.1.37
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发表时间：
1992
影响因子：
2.5
通讯作者：
Warren,S
中科院分区：
文献类型：
--
作者：
Gardner,EP;Palmer,CI;Hamalainen,HA;Warren,S
1.为了评估皮层神经元感知皮肤运动的机制，我们使用计算机控制的OPTACON刺激器对手部无毛皮肤上的一系列相邻位置进行脉动刺激。我们描述了警觉猴子初级躯体感觉皮质中129个单个神经元对水平条形图案的反应，水平条形图案以10、20和40毫秒的间隔(分别为100、50和25赫兹)以1.2毫米的步长向近端或远端移动。这些频率跨越了人类表面运动的感知范围，从平滑的、不间断的扫描转变为一系列不同的脉冲，这些脉冲被分解为单独的事件。因此，这些实验旨在破译区分连续运动和离散敲击的神经关联。2.在触觉阵列上，以移动条形图案定位的皮质感受野跨度为5-24行(16.2+/-5.4，平均+/-SD)。超过40%的视野包含18行或更多行(大于或等于21.6 mm)，允许这些神经元整合显示在OPTACON上的整个图像的空间信息。皮质感受场比机械感受器的感受场大得多，机械感受器以相同的移动条形模式(4.2+/-2.3行，平均+/-SD)定位，反映了皮质下和皮质中继器的汇聚输入。根据刺激频率的不同，在整个视野中的反应是相对一致的，或者在最初进入点时反应最强。在这项研究中记录的大多数细胞中都没有明确定义的场中心。3.刺激的时间频率似乎是皮层放电模式的主要决定因素。低频刺激在激活皮质神经元方面更有效，每次扫描产生更多的尖峰，对单个刺激的相位锁定比高频刺激更大。在10-40ms范围内，皮层神经元的总棘波输出与脉冲间隔成正比，脉冲周期平均增加5.9个脉冲/10ms。当脉冲间隔较长时，峰值放电率和调制幅度也最高，随着刺激频率的增加而显著下降。在高脉冲率下放电的减少显然是由于中枢机制，因为当用相同的条形图案测试时，快速适应和环状小体传入都显示出几乎恒定的尖峰输出和场内一致的灵敏度。因此，中央网络就像低通滤波器一样，减少了大脑皮质对快速施加的连续刺激的反应。
1. To assess the mechanisms used by cortical neurons to sense motion across the skin, we applied pulsatile stimuli to a series of adjacent positions on the glabrous skin of the hand using a computer-controlled OPTACON stimulator. We describe responses of 129 single neurons in primary somatosensory cortex of alert monkeys to a horizontal bar pattern that was displaced proximally or distally in 1.2-mm steps at 10-, 20-, and 40-ms intervals (100, 50, and 25 Hz, respectively). These frequencies span the range in which apparent motion is transformed perceptually in humans from a smooth uninterrupted sweep into a series of distinct pulses that are resolved as separate events. The experiments are thus designed to decipher the neural correlates distinguishing continuous motion from discrete taps. 2. Cortical receptive fields mapped with moving bar patterns spanned 5-24 rows on the tactile array (16.2 +/- 5.4, mean +/- SD). Over 40% of the fields encompassed 18 or more rows (greater than or equal to 21.6 mm), allowing these neurons to integrate spatial information from an entire image displayed on the OPTACON. Cortical receptive fields are considerably larger than those of mechanoreceptors mapped with the same moving bar patterns (4.2 +/- 2.3 rows, mean +/- SD), reflecting convergent inputs in subcortical and cortical relays. Responses were either relatively uniform across the field or strongest at the initial point of entry, depending on the frequency of stimulation. A sharply defined field center was absent from most of the cells recorded in this study. 3. Temporal frequency of stimulation appears to be a major determinant of cortical firing patterns. Low-frequency stimuli are more effective in activating cortical neurons, producing more spikes per sweep and greater phase-locking to individual stimuli than do high frequencies. The total spike output of cortical neurons is proportional to the pulse interval over the range 10-40 ms, increasing linearly by an average of 5.9 spikes/10-ms increase in pulse period. Peak firing rates and modulation amplitude are also highest when pulses are presented at long intervals, falling significantly as the stimulation frequency rises. The reduction in firing at high pulse rates is apparently due to central mechanisms, as both rapidly adapting and Pacinian corpuscle afferents display nearly constant spike outputs and uniform sensitivity within the field when tested with identical bar patterns. Central networks thus behave as low-pass filters, reducing cortical responses to rapidly applied sequential stimuli.(ABSTRACT TRUNCATED AT 400 WORDS)