Hughes Kendall L, Gaffin Douglas D
Department of Biology, University of Oklahoma, Norman, OK, 73019, USA.
Invert Neurosci. 2019 Jul 31;19(3):9. doi: 10.1007/s10158-019-0228-8.
Scorpion pectines detect chemical and physical stimuli via thousands of peg sensilla on ground-facing teeth. Each sensillum has multiple neurons that detect stimuli and transmit neural impulses to the subesophageal ganglion (SEG) in the central nervous system. Anatomically, the organization of the pectinal neuropil in the SEG reflects the arrangement of pectinal teeth, suggesting conservation of information about stimulus location in the SEG. In this study, neural impulses from the pectinal nerve of the striped bark scorpion (Centruroides vittatus) were recorded in the pecten, abdominal cavity, and SEG using electrophysiology. Recordings from the right pectinal nerve in the pecten showed that right tooth stimulations elicit sensory activity milliseconds before motor feedback, while left tooth stimulations only evoked motor spikes, suggesting no contralateral afferent communication between pectines. In the abdominal cavity recordings, two distinct waveforms (PN1 and PN2) were detected in baseline activity; PN1 seemed to enhance the likelihood that PN2 would fire, suggesting a possible excitatory interaction. Recordings from the SEG showed that mechanically stimulating different pectinal teeth evoked different compound neural activity patterns in the same SEG location. Stimulating the same tooth in succession showed mechanosensory adaptation. These recordings show promise for continued electrophysiological investigations of the scorpion SEG, and, in particular, how information from the pectines is processed and used for orientation.
蝎子的栉状器通过面向地面的齿上的数千个栓状感器来检测化学和物理刺激。每个感器都有多个神经元，这些神经元检测刺激并将神经冲动传递到中枢神经系统的咽下神经节（SEG）。从解剖学上看，SEG中栉状神经纤维网的组织反映了栉状齿的排列，这表明SEG中关于刺激位置的信息得以保留。在本研究中，使用电生理学方法在栉状器、腹腔和SEG中记录了条纹树皮蝎（Centruroides vittatus）栉状神经的神经冲动。在栉状器中对右侧栉状神经的记录表明，右侧齿的刺激在运动反馈前几毫秒就引发了感觉活动，而左侧齿的刺激仅诱发了运动尖峰，这表明栉状器之间不存在对侧传入通信。在腹腔记录中，在基线活动中检测到两种不同的波形（PN1和PN2）；PN1似乎增加了PN2放电的可能性，这表明可能存在兴奋性相互作用。在SEG的记录表明，机械刺激不同的栉状齿会在同一SEG位置诱发不同的复合神经活动模式。连续刺激同一颗齿会出现机械感觉适应。这些记录为对蝎子SEG继续进行电生理学研究，特别是对来自栉状器的信息如何被处理并用于定向的研究，带来了希望。
