Gaffin D D, Brownell P H
Department of Zoology, Oregon State University, Corvallis 97331-2914, USA. ddgaffin@.edu
J Comp Physiol A. 1997 Sep;181(3):301-7. doi: 10.1007/s003590050116.
The pectines of scorpions are ventral bilateral appendages supporting 10(4)-10(5) chemosensory sensilla called pegs. Each peg contains 10-18 sensory neurons, some of which show ultrastructural evidence of axo-axonic synapses with other sensory neurons in the same sensillum. In extracellular recordings from single-peg sensilla, individual sensory units can be distinguished by impulse waveform and firing frequency. Cross-correlation analysis of impulse activity showed that at least two of these units, types 'A1' and 'A2', are inhibited during the 100-ms period immediately following activity of a third unit, type 'B'. This interaction between sensory units in a single sensillum also occurs in surgically isolated pectines, indicating that it does not involve efferent feedback from the central nervous system. Other sensillar neurons appear to have excitatory interactions. Thus, in scorpion pectine, chemosensory information undergoes some form of processing within individual sensilla prior to its relay to the CNS, making this an unusually accessible preparation for study of first-order chemosensory processing events.
蝎子的栉状器是腹侧双侧附肢，其上支撑着10⁴-10⁵个被称为栉齿的化学感应感受器。每个栉齿包含10-18个感觉神经元，其中一些在超微结构上显示出与同一感受器中的其他感觉神经元存在轴-轴突触。在对单个栉齿感受器进行细胞外记录时，单个感觉单元可通过冲动波形和放电频率加以区分。对冲动活动的互相关分析表明，在第三个单元（“B”型）活动后的紧接着的100毫秒期间，这些单元中至少有两个单元（“A1”型和“A2”型）受到抑制。单个感受器内感觉单元之间的这种相互作用在手术分离的栉状器中也会出现，这表明它不涉及来自中枢神经系统的传出反馈。其他感受器神经元似乎存在兴奋性相互作用。因此，在蝎子的栉状器中，化学感应信息在传递到中枢神经系统之前，会在单个感受器内经历某种形式的处理，这使得它成为研究一级化学感应处理事件的一个异常便于研究的标本。
