Memory processing has been investigated in day-old chickens and in adult goldfish. In chicks, bilateral vs. unilateral storage of monocularly-acquired one-trial passive avoidance was examined using unilateral lesions of the avian telencephalon. Interocular transfer tested 24 hr after training was observed after lesions of the trained hemisphere delayed 2-18 hr after the training trial. Bilateral lesions abolished task performance. It is concluded that memory for one-trial passive avoidance is established bilaterally in the brain and that the telencephalon contributes either as a storage area or as a relay in retrieval. Results of unilateral lesions delayed 2 min after training also suggested bilateral storage, in contrast to published reports of apparent unilateral storage of the same task after unilateral. injection of cycloheximide 2 min after training. The disparity between results may be the result of more general disruption of brain function produced by protein synthesis inhibitors; cycloheximide may interfere with transfer of sensory information or depress brain function so as to prevent the normal establishment of bilateral traces. Adult goldfish were used to examine the roles of the optic tectum and forebrain in memory storage of color discrimination using conditioned respiratory suppression as the behavioral measure. Highly localized training of discrete tectal areas was followed by lesions of trained tectal regions or by bilateral forebrain lesions. Excellent intraretinal generalization to the remainder of the visual field of the trained eye was observed. Interocular transfer across the entire visual field of the untrained eye occurred after training in the posterior visual field. Complete tectal ablation after localized training did not produce deficits in interocular transfer. It is concluded that binocular regions of the visual field in goldfish do not integrate color discrimination better than do monocular regions and that memory storage may occur bilaterally in the brain. Findings of apparent bilateral memory storage in birds and fish are related to studies of memory in mammalian species. It is suggested that the parallel processing methods observed may reflect selection procedures which occurred early in the evolutionary development of behavior in vertebrates.
Karen Faye Greif (Thu,) studied this question.