Journal of Neurophysiology, Vol 50, Issue 1 162-177, Copyright © 1983 by APS
Swimming pattern in intact and decerebrated stingrays
M. H. Droge and R. B. Leonard
Stingrays swim with a rostral-to-caudal wave of elevation and depression of
the enlarged pectoral fins. The present study compares the timing relations
of swimming before and after decerebration in the same animals using
electromyograms (EMGs). EMGs were recorded from several freely swimming,
intact animals. Most recordings, however, were from stingrays suspended by
vertebral clamps. Activity recorded from restrained animals exhibited the
same timing relations as freely swimming animals. Therefore, the restrained
preparation was used to compare locomotor rhythm in intact and decerebrate
stingrays. The delay from the onset of activity recorded at a rostral
segment to the onset of activity at successively caudal recording sites
(intersegmental delay) was linearly related to the extent of the segmental
separation. This relation was not changed by decerebration. Both the
intersegmental delay and the EMG burst duration were linearly related to
the period of the swim cycle. The intercepts for both relations fell around
the origin. Therefore, stingray swimming demonstrates constant phase
coupling. Neither the slopes nor the intercepts of the coupling relations
were altered by decerebration. Histological examination of the fins
indicates that at least two types of muscles exist. Superficial muscle is
activated during slow swimming, while the deeper muscle is recruited during
faster swimming.
