Pubols B H, Pubols L M
Fed Proc. 1983 Jun;42(9):2528-35.
Current knowledge of the functional properties of mammalian cutaneous mechanoreceptors is reviewed with special reference to receptors associated with the glabrous skin of the raccoon and squirrel monkey hand. Four physiologically defined mechanoreceptor types are recognized: Pacinian afferents, rapidly adapting (RA), and slowly adapting type I (SAI), and slowly adapting type II (SAII). The SAI category is divided into moderately slowly adapting and very slowly adapting (VSA) types in terms of the duration of their response to a prolonged mechanical displacement of skin. Although both RA and SA units are capable of signaling displacement ramp velocity, the pattern of discharge during ramp stimulation may vary widely among units. SAI units also code the depth of skin displacement, but there is no best-fitting function describing the relationship. Static discharge is also markedly influenced by prior ramp velocity. Both raccoon and squirrel monkey VSA units show wide variation in the regularity of their discharge during static displacement. The rate of adaptation of SAI units is less when constant force stimuli are applied to the skin than when constant displacement stimuli are applied. This is partly attributable to mechanical properties of the skin. When either constant force or constant displacement stimuli are spaced too closely in time, there is a progressive (trial-to-trial) decrement in response rate, accounted for in part by failure of the skin to recover to its initial resting level.
本文回顾了哺乳动物皮肤机械感受器功能特性的当前知识，特别提及了与浣熊和松鼠猴手部无毛皮肤相关的感受器。已识别出四种生理上定义的机械感受器类型：环层小体传入纤维、快速适应（RA）、慢适应I型（SAI）和慢适应II型（SAII）。根据SAI对皮肤长时间机械位移的反应持续时间，SAI类别又分为中度慢适应和极慢适应（VSA）类型。虽然RA和SA单位都能够对位移斜坡速度进行信号编码，但斜坡刺激期间的放电模式在不同单位之间可能有很大差异。SAI单位也对皮肤位移深度进行编码，但没有描述这种关系的最佳拟合函数。静态放电也明显受先前斜坡速度的影响。浣熊和松鼠猴的VSA单位在静态位移期间的放电规律性上都表现出很大差异。当对皮肤施加恒力刺激时，SAI单位的适应速率比施加恒定位移刺激时要小。这部分归因于皮肤的机械特性。当恒力或恒定位移刺激在时间上间隔过近时，反应速率会逐渐（逐次试验）下降，部分原因是皮肤未能恢复到其初始静止水平。
