INCREASES IN NEURONAL BURSTING RECORDED FROM THE CHICK LOBUS-PAROLFACTORIUS AFTER TRAINING ARE BOTH TIME-DEPENDENT AND MEMORY-SPECIFIC

Day-old-chicks can be trained in one trial to avoid a methylanthranila te-coated bead (methyl-chicks). The lobus parolfactorius of the chick forebrain is an important structure for memory of this avoidance respo nse. To examine training-induced electrophysiological changes in this structure, spontaneous neuronal bursting activity was measured from th e lobus parolfactorius of anaesthetized, day-old methyl- and water-chi cks (the latter chicks trained to peck at a water-coated bead) over th e period 1 - 10 h post-test. Bursting was significantly higher in meth yl-chicks over this period. This post-test increase was time-dependent : bursting in methyl-chicks was significantly higher only during the p eriod 4 - 7 h post-test. In a second experiment, methyl-chicks were su bjected to brief, subconvulsive electroshock 5 min post-training. When tested 1 h later about half of these chicks showed recall (avoided th e bead) and half were amnesic (pecked the bead). These chicks were ana esthetized and bursting was recorded from the lobus parolfactorius. Ch icks that showed recall exhibited a significantly higher level of burs ting over the period 1 - 10 h post-test when compared to chicks that w ere amnesic. The time course of bursting was similar to that seen in n on-electroshocked methyl-chicks. These results suggest that passive av oidance training induces a memory-specific, time-dependent increase in neuronal activity within the lobus parolfactorius of day-old chicks. This increase may be directly associated with long-term consolidation of memory for the task.