Discriminative taste aversion learning: a learning task for older chickens.

The study of learning and memory using the chicken model has relied on three learning paradigms, passive avoidance learning, imprinting and the pebble floor task. Passive avoidance learning and imprinting have been used predominantly in very young chickens and cannot be used to access learning and memory in older chickens. We have established a new behavioural learning paradigm, Discriminative Taste Aversion Learning (DTAL), that can be used with both young and older animals. The task requires chickens to discriminate between food crumbs dyed either red or yellow with one colour being associated with the aversive tasting substance, methylanthranilate. Learning can be tested at various times after the training session by presenting chickens with the coloured food crumbs without an aversive taste. Both chickens tested at 5 and 15 days post-hatch learned to avoid the aversive crumbs. Furthermore, the protein synthesis inhibitor anisomycin (30 mM; 10 microl per hemisphere) injected into the intermediate medial hyperstriatum ventrale 15 min pre-training or 45 min post-training blocked long-term memory for the DTAL task when tested 24 h later. Memory for the task was unaffected by anisomycin injection 120 min post-training or in control animals injected with saline at similar times. The timing of the cellular processes of protein synthesis needed for consolidation of the DTAL appears to be similar to those described for the other behavioural paradigms in young chickens.