Two Separable Phases of Behaviorally Manifest Memory for One-Trial Learning in Chicks

Abstract

Immediate post-trial administration of transcranial current left a low level of retention at 30 rnin which disappeared within 2 hr. When current administration was delayed for 1 min after training trial, substantial retention was observed at 30 min which increased to asymptotic level at 1 hr. These results may indicate the existence of 2 phases of measurable memory. Phase 1 is immune or only partially susceptible to current disruption and lasts for at least 30 min. Phase 2 is induced within seconds after training, but its trace formation is a long process involving several stages; only the beginning stage is current-disruptable, but this phase of memory is not expressed until the entire process is complete.