Jg. Canfield et Gj. Rose, ELECTROSENSORY MODULATION OF ESCAPE RESPONSES, Journal of comparative physiology. A, Sensory, neural, and behavioral physiology, 173(4), 1993, pp. 463-474
Once initiated, rapid escape responses of teleost fishes are thought t
o be completed without additional sensory modification. This suggests
that the motor program for a particular response is selected for by th
e constellation of sensory cues existing at the time of the releasing
stimulus. This paper presents initial evidence that a highly specializ
ed, phylogenetically recent electrosensory system is integrated with a
primitive motor system and allows an animal to continuously monitor i
ts environment for producing accurate escape behaviors. Behavioral tes
ting for directed startle responses in a ''Y-maze'' demonstrates that
when presented immediately before an acoustic startle stimulus, electr
ic fish (Eigenmannia virescens), direct their response away from the c
ue (a transient shorting of their electric field). Thus, electrosensor
y cues as brief as 100 ms provide directional information to the escap
e motor network. In electric fish that are curarized to facilitate int
racellular recording, the normal electric organ discharge is attenuate
d. When al electronically generated replacement field of the same freq
uency and amplitude as the fish's normal signal is shorted, a fast-ris
ing, 7 ms latency post-synaptic potential is evoked from the Mauthner
cell. Similar PSPs are generated by turning the replacement stimulus o
n and off. In some recordings, removing the S1 replacement field elici
ts a rebound of other afferent activity to the Mauthner cell; replacin
g the field suppresses this activity.