Fig. 2. Discharge pattern of the forewing (A) and hindwing (B) tegula in relation
to wing position during tethered flight. Wing position (top traces in i) was
monitored by an optical position detector. Tegula activity (bottom traces) was
recorded extracellularly from nerve branches N1 (B) or N1C (A) (details in
Pearson and Wolf, 1988), which
supply the tegula organs. Black arrowheads indicate cross-talk between
motoneurons innervating the dorsal longitudinal depressor muscles.
Electromyographic (EMG) recordings were made from wing depressor (M97, M127)
and elevator (M83, M113) muscles. Shaded areas indicate tegula burst duration
and latency (time between onset of wing downstroke and start of tegula
discharge). Cycle period was determined as the time between consecutive
downstroke movements. The downstroke interval was measured between the
beginning and end of the downstroke movement. Stroke amplitude was determined
from the distance between the upper and lower reversal points of the wing. The
angular velocity of the wing (
, rad s-1) was calculated from
the change in wing position during the 10 ms period following tegula
activation (indicated by the open boxes in Ai and Bi). The phase of onset of
tegula activity within a cycle was calculated as latency divided by cycle
period. (Aii,Bii). Nerve recordings after ablation of the tegula organs
recorded in Ai and Bi (traces selected and aligned according to EMG activity,
which is not shown).
