Responses of Cricket Leg Motoneurons to Air-Current Stimuli : Velocity Dependent Inhibition and Acceleration Dependent Excitation(Physiology)
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概要
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Motoneurons (MNs) innervating the levator and the depressor muscles of the mesothoracic leg trochanter of the cricket, Gryllus bimaculatus, respond to sinusoidal air-current stimuli. The MNs habituate during repetition of the air-current stimulus. The rate of habituation depends on the inter-stimulus interval. The slow, spontaneously active MNs show a brief inhibition prior to the excitatory response to the air-current. These slow MNs show a post-excitatory suppression. The degree of suppression depends on the number of spikes in the excitatory response preceded. The response of MNs to air-current stimuli varied strikingly with temperature. A small drop in temperature results in a delayed and a long-lasting suppression of spike activity. The frequency-threshold curves for a single stimulus were measured. The thresholds for the brief inhibition prior to the excitation were low and velocity dependent (ca. 1 mm/sec). The thresholds for excitation were high, and some of them were acceleration dependent (ca. 500 mm/sec^2). Two different groups of excitatory threshold curves were traced in the same MN in different preparations. This suggests a functional switching or a predisposition of the motor network to which the cereal interneurons (CIs) connect. Based on the threshold curves of the MNs, it is evident that two small diameter CIs, 10-2 and 10-3, driven by the long cereal filiform hairs initially inhibit the MNs. The following excitation of the MNs seems to be brought on by the large diameter CIs such as 8-1 (MGI) and 9-1 (LGI).
- 社団法人日本動物学会の論文
- 1985-10-15
著者
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Shimozawa Tateo
Division Of Behaviour And Neurobiology National Institute For Basic Biology
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Kanou Masamichi
Zoological Institute Faculty Of Science Hokkaido University