Hamalainen H A, Warren S, Gardner E P
Somatosens Res. 1985;2(4):281-302. doi: 10.3109/07367228509144569.
To compare the relative sensitivities of glabrous and hairy skin, we measured reaction times (RTs) and detectability (d') of airpuffs delivered to the hairy dorsum and glabrous thenar eminence of the hand of six human subjects. In contrast to previous studies with mechanical contact stimuli, airpuffs applied to hairy skin were detected with equal or greater fidelity than airpuffs tested on glabrous skin. Mean RTs to three simultaneously applied airpuffs were significantly shorter (p less than .005) on hairy skin in five of six subjects, and in 74% of paired sessions; no significant difference in mean RTs was observed in 16% of the sessions. The superiority of hairy skin was less evident, however, when single airpuffs were tested, as significantly shorter responses were observed on only 45% of the paired sessions, and nearly identical responses on 38% of the sessions. Detectability of airpuffs (d'), which is independent of the value of RTs, was identical on hairy and glabrous skin at high airpuff intensities (1,600 dyn), and superior (n = 4) or equal (n = 2) on hairy skin with low airpuff intensities (800 dyn). Spatial summation was more pronounced on hairy than on glabrous skin. Three simultaneously presented airpuffs produced significantly shorter RTs than one airpuff in 85% of the paired sessions on hairy skin, but on only half of the sessions on glabrous skin. The spatial distribution of stimulus force was less important on hairy skin, as three low-intensity airpuffs produced the same or shorter RTs than one high-intensity airpuff. By contrast, on glabrous skin, detectability was significantly better when force was concentrated at a single point (1 X 1,600 dyn) than when diffused over a wide skin area (3 X 800 dyn). The enhanced sensitivity of hairy skin to airpuffs appears partially attributable to hair motion in the airstream. After hair removal by chemical depilation, detectability of airpuffs was reduced on hairy skin to a level equal to or below that on glabrous skin. Spatial summation on the depilated skin corresponded to that observed on the intact hairy skin, indicating that depilation did not abolish intensity discrimination, but rather lowered the overall sensitivity of hairy skin. These results show that hair follicle units form a very sensitive detection mechanism on hairy skin of the human hand, similar to that provided by Meissner's and Pacinian afferents in glabrous skin. These findings with airpuffs provide the first example of a tactile stimulus that is less effective for mechanoreceptors in glabrous skin than in hairy skin.(ABSTRACT TRUNCATED AT 400 WORDS)
为比较无毛皮肤和有毛皮肤的相对敏感性，我们测量了六位人类受试者手部有毛的背部和无毛的鱼际隆起处受到气吹刺激后的反应时间（RTs）和可检测性（d'）。与先前关于机械接触刺激的研究不同，施加于有毛皮肤的气吹刺激比施加于无毛皮肤的气吹刺激能以相同或更高的保真度被检测到。六位受试者中有五位对同时施加的三次气吹刺激的平均反应时间在有毛皮肤上显著更短（p小于0.005），且在74%的配对实验中如此；在16%的实验中未观察到平均反应时间有显著差异。然而，当测试单个气吹刺激时，有毛皮肤的优势不太明显，因为在仅45%的配对实验中观察到反应显著更短，在38%的实验中反应几乎相同。气吹刺激的可检测性（d'）与反应时间的值无关，在高气吹强度（1600达因）时，有毛皮肤和无毛皮肤的可检测性相同，在低气吹强度（800达因）时，有毛皮肤的可检测性更高（n =4）或相同（n =2）。空间总和在有毛皮肤上比在无毛皮肤上更显著。在有毛皮肤上，85%的配对实验中，同时呈现的三次气吹刺激产生 的反应时间比单次气吹刺激显著更短，但在无毛皮肤上只有一半的实验如此。刺激力的空间分布在有毛皮肤上不太重要，因为三次低强度气吹刺激产生的反应时间与一次高强度气吹刺激相同或更短。相比之下，在无毛皮肤上，当力集中在单个点（1×1600达因）时比分散在大面积皮肤上（3×800达因）时可检测性显著更好。有毛皮肤对气吹刺激的敏感性增强似乎部分归因于气流中的毛发运动。通过化学脱毛去除毛发后，有毛皮肤上气吹刺激的可检测性降低到与无毛皮肤相同或更低的水平。脱毛皮肤上的空间总和与完整有毛皮肤上观察到的情况一致，表明脱毛并未消除强度辨别，而是降低了有毛皮肤的整体敏感性。这些结果表明，毛囊单位在人类手部的有毛皮肤上形成了一种非常敏感的检测机制，类似于无毛皮肤中的迈斯纳氏小体和环层小体传入纤维所提供的机制。这些关于气吹刺激的发现提供了第一个触觉刺激的例子，即该触觉刺激对无毛皮肤中的机械感受器的作用比对有毛皮肤中的机械感受器的作用更弱。（摘要截断于400字）
