Modification of a weak learning experience by memory retrieval in the day-old chick

Activation of memory retrieval after weak learning (WL), during either the short- or intermediate-term stages of memory in day-old chickens, resulted in the strengthening of the memory to levels normally associated with stron g learning. Administration of the calcium channel antagonist lanthanum chlo ride, the glutamate receptor agonist monosodium glutamate, or the N-methyl- D-aspartate glutamatergic receptor antagonist AP5 prevented strengthening o f a WL memory by reminder-activated memory retrieval. The results of this s tudy are discussed in light of our recent findings suggesting two phases of memory retrieval in the day-old chick. The results are consistent with the proposition that a memory undergoing the processes of formation may be mod ified to include information gleaned at the time of memory retrieval and th at a second phase of memory retrieval may be responsible for such modificat ion.