Brecht M, Preilowski B, Merzenich M M
Tübingen University, Germany.
Behav Brain Res. 1997 Mar;84(1-2):81-97. doi: 10.1016/s0166-4328(97)83328-1.
We investigated the transduction operation and function of the mystacial vibrissae, using a comparative morphological analysis and behavioral experiments in rats. Vibrissal architecture was documented in a series of mammals to identify evolutionary conserved features of vibrissal organization. As a result of this analysis, we distinguish between a frontal microvibrissal system and macrovibrissal system of the mystacial pad. The latter was invariably comprised of whiskers aligned in regular rows. In each row, whiskers were oriented perpendicular to the animal's rostrocaudal axis; all shared a specific dorsoventral orientation. In all species, progressing from rostral to caudal in any vibrissal row, there was a precisely exponential increase in whisker length. Each whisker appeared to act as a lever-like transducer, providing information as to whether or not--but not where--an individual vibrissa had been deflected. The rat's frontal microvibrissae system was found to have a vibrissa tip density that was about 40 times higher than that of the mystacial macrovibrissae. In behavioral studies spatial tasks and object recognition tasks were used to investigate (a) search behaviors; (b) single whisker movements; (c) object recognition ability; and (d) effects of selective macro- or microvibrissae removal on task performances. A clear distinction between the functional roles of macro- and microvibrissae was demonstrated in these studies. Mystacial macrovibrissae were critically involved in spatial tasks, but were not essential for object recognition. Microvibrissae were critically involved in object recognition tasks, but were not essential for spatial tasks. A synthesis of these morphological and behavioral data led to the following functional concept: The mystacial macrovibrissae row is a distance decoder. Its function is to derive head centered obstacle/opening contours at the various dorsoventral angles represented by vibrissal rows. This distance detector model is functionally very different from traditional concepts of whisker function, in which the mystacial whiskers were hypothesized to form a fine grain skin-like object-recognizing tactile surface.
我们通过对大鼠进行比较形态学分析和行为实验，研究了口鼻部触须的转导操作及功能。记录了一系列哺乳动物的触须结构，以确定触须组织在进化过程中保守的特征。通过该分析，我们区分了口鼻垫的额部微触须系统和大触须系统。后者总是由规则排列成行的须毛组成。在每一行中，须毛垂直于动物的头尾轴排列；所有须毛都具有特定的背腹方向。在所有物种中，在任何一行触须中从吻端向尾端移动时，须毛长度都精确地呈指数增长。每根须毛似乎都起到杠杆状换能器的作用，提供关于某一根触须是否被偏转的信息，但不提供其被偏转位置的信息。发现大鼠的额部微触须系统的触须尖端密度比口鼻部大触须的密度高约40倍。在行为研究中，使用空间任务和物体识别任务来研究：（a）搜索行为；（b）单根触须的运动；（c）物体识别能力；以及（d）选择性去除大触须或微触须对任务表现的影响。这些研究表明大触须和微触须在功能作用上有明显区别。口鼻部大触须在空间任务中起关键作用，但对物体识别并非必不可少。微触须在物体识别任务中起关键作用，但对空间任务并非必不可少。这些形态学和行为学数据的综合得出了以下功能概念：口鼻部大触须排是一个距离解码器。其功能是在由触须排所代表的不同背腹角度处得出以头部为中心的障碍物/开口轮廓。这种距离探测器模型在功能上与传统的触须功能概念有很大不同，在传统概念中，口鼻部触须被假定形成一个类似精细皮肤的物体识别触觉表面。
