TACTILE ROUGHNESS - NEURAL CODES THAT ACCOUNT FOR PSYCHOPHYSICAL MAGNITUDE ESTIMATES
TACTILE ROUGHNESS - NEURAL CODES THAT ACCOUNT FOR PSYCHOPHYSICAL MAGNITUDE ESTIMATES
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DOI：
10.1523/jneurosci.10-12-03823.1990
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发表时间：
1990-12-01
影响因子：
5.3
通讯作者：
JOHNSON, KO
中科院分区：
文献类型：
--
作者：
CONNOR, CE;HSIAO, SS;JOHNSON, KO
假设的神经编码背后的感觉触觉粗糙被调查在一个联合的心理物理和神经生理学研究。刺激集由塑料表面压花的点阵列不同的点直径和中心到中心的间距。人类受试者用食指垫探索每个表面，并报告他们主观感觉的粗糙程度。在记录诱发动作电位的同时，对猴子皮肤机械感受传入的感受野进行了相同的表面扫描。从神经反应模式中计算出粗糙程度的假设神经编码，并测试其解释心理物理数据的能力。心理物理结果表明，主观粗糙度值与点间距呈倒u型函数关系，在点间距3.0 mm附近达到峰值，并且在所有点间距下，点直径的增加都会导致粗糙度值的降低。假设的神经编码在所有这些刺激条件下与粗糙度大小没有一致的关系，可以被拒绝作为粗糙度的编码。考虑了四种类型的神经编码。它们基于(1)平均射击率，(2)射击率的一般变化，(3)射击率的短期时间变化，(4)射击率的局部空间变化。平均放电率无法解释心理物理结果：引起相同放电率的表面通常引起非常不同的粗糙度判断。相反，基于放电速率变化的神经编码，特别是在缓慢适应的传入事件中，解释了心理物理结果。
Hypothetical neural codes underlying the sensation of tactile roughness were investigated in a combined psychophysical and neurophysiological study. The stimulus set consisted of plastic surfaces embossed with dot arrays of varying dot diameter and center-to-center spacing. Human subjects explored each surface with the pad of the index finger and reported their subjective sense of roughness magnitude. The same surfaces were scanned across the receptive fields of cutaneous mechanoreceptive afferents in monkeys while recording the evoked action potentials. Hypothetical neural codes for roughness magnitude were computed from the neural response patterns and tested for their ability to account for the psychophysical data. The psychophysical results showed that subjective roughness magnitude is an inverted U-shaped function of dot spacing that peaks near 3.0 mm spacing, and that increased dot diameter produces decreased roughness sensations at all dot spacings. Hypothetical neural codes that do not bear a consistent relationship to roughness magnitude across all of these stimulus conditions can be rejected as the code for roughness. Four types of neural codes were considered. They were based on (1) mean firing rate, (2) general variation in firing rate, (3) short-term temporal variation in firing rate, and (4) local spatial variation in firing rate. Mean firing rate failed to explain the psychophysical results: surfaces that evoked the same firing rate often evoked very different roughness judgments. In contrast, neural codes based on firing-rate variation, especially in slowly adapting afferents, account for the psychophysical results.