Recalling an aversive experience by day-old chicks is not dependent on somatic protein synthesis

Abstract

Long-term memory is dependent on protein synthesis and inhibiting such synthesis following training results in amnesia for the task. Proteins synthesized during training must be transported to the synapse and disrupting microtubules with Colchicines, and hence, blocking transport, results in transient amnesia. Reactivating memory for a previously learned avoidance triggers a biochemical cascade analogous to that following the initial training and renders the memory labile once more to protein synthesis inhibitors. However, the reminder-induced cascade differs in certain key features from that following training. Here we show that in a one-trial passive avoidance task in chicks, in contrast with initial consolidation following training, memory following a reminder is not impaired by Colchicine. We conclude that recall after a reminder does not require synaptic access to somatically synthesized proteins in this task. Our results support the hypothesis that in the chick, a reminder may instead engage local protein synthesis at the synapse, rather than in the soma.