. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 364 ERIC I. KNUDSEN B. FIGURE 6. Flexor burst records during gradual (A) and abrupt (B) transitions from ventilation to swimming. Both recordings are from the first -ill plate flexor, but (A) is at a lower gain than (B). Bar indicates 1 sec. DISCUSSION Interpretation of the muscle activity graphs in Figure 2 gives some insight as to the underlying motoneuron activity corresponding to ventilation, hyperventila- tion. and swimming. If each ventilatory motor burst consists of a nearly equal number of motoneuron discharges, then
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 364 ERIC I. KNUDSEN B. FIGURE 6. Flexor burst records during gradual (A) and abrupt (B) transitions from ventilation to swimming. Both recordings are from the first -ill plate flexor, but (A) is at a lower gain than (B). Bar indicates 1 sec. DISCUSSION Interpretation of the muscle activity graphs in Figure 2 gives some insight as to the underlying motoneuron activity corresponding to ventilation, hyperventila- tion. and swimming. If each ventilatory motor burst consists of a nearly equal number of motoneuron discharges, then the observed decrease in burst duration would entail a progressively smaller interspike interval. Assuming that the opisthosomal flexor and extensor muscles undergo summation and facilitation, such a reduction in interspike interval would explain the observed increase in muscle potential amplitude. The amplitude change in the muscle activity with the onset of hyperventilation may result from recruitment of motoneurons causing additional muscular summation and facilitation. The burst shape transition from symmetrical to saw-tooth (Fig. Ic), noted during periods of hyperventilation, may represent -' ' . B ^;,^^_^n — ,-,, .*,-••• .•,-- FIGURE 7. The effect of progressive isolation of the opisthosomal ganglia upon ventilatory activity in the flexor muscles of gill plates one through four (in order from top to bottom). The rhythmic, metachronal muscle potentials in (A) are typical of normal ventilatory activity. Desynchromized activity of the fourth gill plate flexor muscles, shown in (B), occured after the connectives between the third and fourth ganglia were severed. Muscle bursts following the isolation of all opisthosomal ganglia, (C), demonstrate some loose coordination of activity. Bar indicates 1 Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
