Neural mechanism of habituation of crayfish escape behavior

点击翻译按钮获取中文摘要

(1) The retention time of the habituation of crayfish escape behavior is depended upon the frequency of applied stimulus (ISI). With a short ISI, crayfish habituate readily but recover quickly. With a long ISI, crayfish habituate slowly and the retention time is depended upon the post-habituation rest in the crayfish. If a period of the rest is short, LGs can give rise to spike. By contrast, if crayfish take a rest for an hour, stimulation fails to give rise to spike in the LGs. (2) LGs are activated by mono- and disynaptic pathways from mechanosensory afferents. A short letency EPSP is called as α component and longer latency EPSP as β component. The depression of EPSPs was different in each term retaining habituation. In a short-term retaining habituation, only EPSP of longer latency is decreased in amplitude, while both short and longer latency EPSPs are decreased in a long-term retaining habituation. Zucker (1971) has proposed that short-term retaining habituation is depended upon the decline in the chemical synaptic transmission between afferents and ascending interneurones but I found no interneurones showed the decline of EPSP amplitude in response to repetitive stimulation that introduces habituation of LGs. (3) Longer latency EPSPs of LG is decreased in amplitute under bath application of d-tubocurarine. These EPSPs are discriminated into two phases, and fast phase of the EPSP is diminished almost completely while later EPSP is only gradually decreased. Hyperpolarization of LG increases EPSP in the later part of α component. Some sensory afferents make direct chemically mediated synaptic connections with LG, and synaptic depression between these affferents and LG mediates habituation of LGs.