Conditioned motor reactions in free-moving elasmobranchs and bony fishes.

Food-getting conditioned motor reflexes to light and darkness discrimination were developed in elasmobranchs (the sharks Scyllium canicula and Galleus canis) and bony fishes (Mugil capitocum). Several distinctions in ecological and conditioned motor behavior were observed in sharks with low and high degrees of organization. There were significant differences between elasmobranchs and bony fishes in ecological and food-getting behavior and in conditioned reflex reactions.

[Compensatory irradiation of excitation following partial deafferentation of the midbrain tectum of Serranus scriba].

The unit activity studies in the fish (Serranus scriba) tectum opticum showed that, after surgical isolation of a retinal segment, there was a slowing of spontaneous unit activity in the partially deafferented portion of the projection area, whereas the firing rate of responses to illumination of the remaining retina increased. Changes in information processes, latencies, and other response characteristics indicate that deafferented neurons could be activated as a result of intratectal spread of excitation.