Dynorphin(1-13) impairs memory formation for aversive and appetitive learning in chicks.

The opioid peptide dynorphin(1-13) impairs memory formation in chicks (5). We examined whether this occurs for both aversively and appetitively motivated learning. Four-day-old chicks were injected with dynorphin(1-13) into the intermediate medial hyperstriatum ventrale and trained on either a peck avoidance (PA) or an appetitive discrimination (AD) task; 2-day-old chicks were trained on PA. In 2-day-old chicks, dynorphin was amnestic for PA at 0.01, 0.03, or 0.1 mM. In 4-day-old chicks, dynorphin impaired memory formation for PA at 0.1 mM, and for AD training at 0.03 mM. Thus, similar doses of dynorphin impair memory formation for both appetitive and aversive conditioning.