The "goatee" of Goatfish : innervation of taste buds in the barbels and their representation in the brain

山羊鱼用一对巨大的下巴须来探测海底，寻找被埋的猎物。这些倒刺上布满了味蕾，但人们对这个系统的神经组织知之甚少。我们发现，倒钩的味蕾以严格的正交方式受到神经支配。倒刺是由倒刺核心的主要神经干支配的。纵向神经束起源于主干，在远端运行一小段后，分为两个环向神经束（CNB），分别向内和向外围绕倒刺伸展。每1毫米长的倒刺上大约有15个cnb。在每个横向水平上，CNB支配两个味蕾簇，每个味蕾簇包含14个末端器官。大脑中的初级味觉中心也同样非凡。来自倒钩的感觉输入终止于派生的背面叶，背面叶具有高度卷曲的表面，形成许多结节。电生理测图实验显示，整个倒钩在体位上表现为面部背叶内弯曲的细长管状。山羊鱼下巴须的神经表征是非常不寻常的，无论是在正交规则的外周神经支配和他们的表征在一个曲折的，弯曲的躯体解剖。这个系统似乎是专门用来让鱼准确辨别埋在沙子里的猎物的深度的。

Goatfishes use a pair of large chin barbels to probe the sea bottom to detect buried prey. The barbels are studded with taste buds but little else is known about the neural organization of this system. We find that the taste buds of the barbel are innervated in a strict orthogonal fashion. The barbel is innervated by a main nerve trunk running in the core of the barbel. A longitudinal nerve bundle originates from the main trunk and after running a short distance distally, divides into two circumferential nerve bundles (CNB) extending respectively, medially and laterally around the barbel. Approximately 15 CNBs innervate each 1 mm length of barbel. At each transverse level, the CNB innervates two clusters of taste buds each containing 14 end organs. The primary taste center in the brain is similarly extraordinary. The sensory inputs from the barbel terminate in a derived dorsal facial lobe which has a highly convoluted surface forming a multitude of tubercles.Electrophysiological mapping experiments show the entire barbel is somatotopically represented as a recurved elongate tubular fashion within the dorsal facial lobe.The neural representation of the chin barbels of goatfish is highly unusual both in terms of the orthogonal regularity of the peripheral innervation and in their representation in a tortuous, recurved somatotopy. The system appears specialized to permit the fish to accurately discern the depth of a prey object buried in the sand.