Spatial Memory of Food Location and the Expression of Synapsin I in the Hippocampus of Pigeons (C. Livia)

Resumen

Experience with environmental space triggers behavioral, cellular and molecular alterations in the hippocampus, which includes induction of transcriptional mechanisms that underlies the formation and consolidation of spatial memory. This study investigated acquisition and consolidation of spatial memory in a food choice situation and patterns of expression of the Synapsin I protein in the hippocampus of pigeons after short- and long-duration training. Male adult pigeons received two (short duration) or 7 sessions (long duration) of training in a food choice situation. Each session had 6 trials in a circular arena with 4 feeders, only one containing food. The choice response was defined as orientation, approach and peck at one feeder. Spatial strategy was tested in one session with feeders removed from the arena. Immunohistochemical analysis of Synapsin I protein was conducted in the hippocampus tissue of pigeons in each group. The latency of the choice response of pigeons trained during 7 days decreased across the training sessions. The number of correct choices increased as function of training, varying between 50% and 88%, in the first and seventh session, respectively. The ANOVA for repeated measures indicated significant differences between groups (p<0.001) and sessions (p<0.001). The cell counts for Synapsin I-positive cells were higher in the hippocampus of E7 pigeons than in the hippocampus of E2 and Control groups (p<0.05). The increases in Synapsin-I expression in response to training can be thought as evidence of playing in long-term excitability within synaptic circuits in the hippocampus.