Westin J, Ritzmann R E, Goddard D J
Department of Biology, Case Western Reserve University, Cleveland, Ohio 44106.
J Neurobiol. 1988 Oct;19(7):573-88. doi: 10.1002/neu.480190702.
The cockroach escape response begins with a turn away from a wind puff such as that generated by an approaching predator. The presence and direction of that wind is detected by hairs on the animal's cerci, and this information is conducted to the thoracic ganglia via two populations of giant interneurons. In the thoracic ganglia, the giant interneurons excite a number of interneurons, at least some of which in turn excite motor neurons that control leg movement. In this paper we examine response properties of various thoracic neurons to wind stimuli originating from different directions. Three sets of thoracic neurons were distinguished on the basis of latency. Type A interneurons had short latencies to wind stimuli (1.3-2.25 ms). Type B interneurons had longer latencies (4-6 ms), and motor neurons had the longest latencies (5.6-17.0 ms). Individual type A interneurons either responded equally to wind from all directions or were biased in their response. Directionality was related to the presence of ventral branches near one or both sides of the midline of the ganglion. Cells with ventral median (VM) branches on either side tended to be omnidirectional or front-rear biased, whereas cells with VM branches on only one side were biased to that side. Although several type B interneurons had strong wind responses and were directionally sensitive, they did not have VM branches. We hypothesize that the presence of VM branches in type A interneurons permits connection with ventral giant interneurons, and this connection accounts for their short latency and directional properties. This hypothesis will be tested in the companion paper.
蟑螂的逃避反应始于其转向远离一阵风，比如由接近的捕食者产生的风。风的存在和方向由动物尾须上的刚毛检测到，并且这个信息通过两类巨型中间神经元传导至胸神经节。在胸神经节中，巨型中间神经元会激发一些中间神经元，其中至少有一些反过来会激发控制腿部运动的运动神经元。在本文中，我们研究了各种胸神经元对来自不同方向的风刺激的反应特性。基于潜伏期区分出了三组胸神经元。A 型中间神经元对风刺激的潜伏期较短（1.3 - 2.25 毫秒）。B 型中间神经元的潜伏期较长（4 - 6 毫秒），而运动神经元的潜伏期最长（5.6 - 17.0 毫秒）。单个 A 型中间神经元要么对来自所有方向的风有同等反应，要么在反应上有偏向性。方向性与神经节中线一侧或两侧附近腹侧分支的存在有关。在两侧都有腹侧中线（VM）分支的细胞往往是全向的或前后偏向的，而仅在一侧有 VM 分支的细胞则偏向该侧。尽管几个 B 型中间神经元有强烈的风反应且具有方向敏感性，但它们没有 VM 分支。我们假设 A 型中间神经元中 VM 分支的存在允许与腹侧巨型中间神经元建立连接，并且这种连接解释了它们的短潜伏期和方向特性。这个假设将在配套论文中进行检验。
