Behavioral modification in a shape discrimination task via brain homogenates

The specificity of behavior modification with brain extracts in a shape discrimination task and the nature of the active substances mediating the phenomenon were investigated. Goldfish, Carassius auratus, 6-7 inches in length were trained to discriminate between two triangular shapes in an appetitive design for each of two phases of the study. Group E1(n=8) was reinforced with a food pellet for an approach to an upright isosceles triangle; Group E2(n=8) was trained to approach an inverted isosceles triangle; Group C (n=8) was a control group which was kept naive with respect to the task but was equated to the experimental groups in terms of deprivation and feeding. Experimental fish received ten trials per day until they reached a criterion of two successive runs of 9 correct responses per 10 responses and at least four days (six days in phase II) of training, at which time they were sacrificed 20 hours after the last trial. Extracts were prepared from each of the groups of pooled brains for Group C, Group E1, and Group E2 for phase I and phase II. In phase I a crude RNA extract was prepared from each group. In phase II, a protein extract, a dialyzate extract, and a retentate extract were prepared from each group. Extracts were injected intracranially into naive 3-4 inch goldfish which were tested at 24, 48, 72, 96, and 120 hours following injection. Each recipient first received ten non-reinforced test trials per day. Injection and testing were done 'blind.' During training and testing, initial responses (choices) and latency measures were recorded. Wilcoxon Matched-Pairs Signed-Ranks tests were applied on the difference (change) of D scores over days. The preference parameter D consisted of the difference between measures at the upright triangle and the inverted triangle. [...]