|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 9. Activity of common inhibitory motor neurones (CIs) before, during and after
thanatosis. The maintenance phase of thanatosis is shaded by grey. (A) Strong
thanatosis in which the recorded F–T joint was maintained at 15°.
Activity of CIs were strongly suppressed especially in the beginning of
thanatosis, then increased gradually towards arousal. Only eight spikes of CIs
were identified in 42 s of the maintenance phase of thanatosis. The strong
recruitment of CIs occurred immediately after arousal despite lack of motion
of the recorded F–T joint at 120° (note that large exciters are
inactive). The increased activity suddenly waned once the cricket started
walking with recruitment of intermediate exciters (Int.). Large truncated
spikes are cross-talk from large motor neurones. (B) Weak thanatosis in which
the recorded F–T joint was maintained at 95°. CI started firing soon
after induction of thanatosis and occurred frequently during thanatosis.
Nevertheless, strong recruitment of CIs occurred immediately after arousal
when the F–T joint was maintained at 90°. Note that CIs fire in
non-ventilatory phases but the smallest slow exciter is activated during
ventilatory phases (inset). (C) Arousal from strong thanatosis. Intermediate
exciter was recruited with some cross-talk from large motor neurones. Note
that a brief pause (asterisk) occurred when the cricket was struggling to
right itself. Large spikes were truncated. (D,E) Time-stretched activity of
labelled bars indicated in C. Note that strong recruitment also occurred in
the slow exciters (causing apparent increase in baseline thickness) although
the F–T joint was maintained same angle (15°) as in thanatosis. (F)
Peri-stimulus time plot of CI activity in the beginning, just before arousal,
and just after arousal. Five trials of thanatosis derived from three
individuals are plotted. One trial (asterisk) indicates thanatosis induced in
normal dorsal-up posture.
|
