Norepinephrine infused into the basolateral amygdala posttraining enhances retention in a spatial water maze task

Recent evidence indicates that the amygdala plays a role in modulating memory processes in other brain regions. For example, posttraining intra-amygdala infusions of amphetamine enhanced memory in both spatial and cued training water maze tasks; these tasks are known to depend on the integrity of the hippocampus and caudate nucleus, respectively. To determine whether this modulation is dependent on noradrenergic activation within a subregion of the amygdala (the basolateral nucleus), the present study examined the effects of posttraining microinfusions (0.2 mu l) of norepinephrine or propranolol into the basolateral amygdala immediately following training in a spatial version of the water maze task. Rats received a four-trial training session on each of 2 consecutive days. On the third day, rats were given a 60-s probe test in the absence of a platform. Retention latencies obtained on the second training day revealed that norepinephrine dose-dependently enhanced retention for the location of the hidden platform. In contrast, propranolol significantly impaired retention. Probe trial analysis revealed that rats treated with 0.25 mu g norepinephrine demonstrated a selective spatial bias for the training platform location relative to all other groups. These findings are consistent with others and support the view that the basolateral amygdala has a role in modulating memory storage by interacting with other brain regions. (C) 1999 academic Press.