Conditioned reflex of color change in fish, angel fish
Tuge, H.; Kanayama, Y.
Japanese Jour Zool 12(4): 585-593
An experiment was undertaken to explore the possibility of basing a conditioned reflex on melanophore concentration, using the angel fish. As the unconditioned stimulus, an epinephrine injection was applied, which caused the fish to pale: the conditioned stimulus was a "bubbling" of water. By several combinations of epinephrine injection with "bubbling", a conditioned paling response was elicited. Also, by this combination a conditioned motor response characteristic to that produced by the epinephrine injection was worked out. However, the conditioned paling and the conditioned motor response appeared to be elicitable independently. Extinction of either the paling or the motor conditioned responses was obtained with a non-reinforced "bubbling". Discussion concerning the nervous mechanism responsible for the melanophore concentration suggests that such conditioned connection may be formed anywhere in the hypothalamic region.