Reinforcement of early long-term potentiation (early-LTP) in dentate gyrusby stimulation of the basolateral amygdala: Heterosynaptic induction mechanisms of late-LTP

The basolateral amygdala (BLA) can influence distinct learning and memory f ormation. Hippocampal long- term potentiation (LTP), the most prominent cel lular model of memory formation, can be modulated by stimulation of the BLA in its induction and early maintenance. However, it is not known how the l ate maintenance of LTP beyond its initial phases might be affected. Behavio ral stimuli have been shown to result in a reinforcement of a transient ear ly- LTP into a lasting potentiation. Here we show that BLA stimulation mimi cs the behavioral effects on early- LTP in freely moving rats when the BLA is activated within a time window of 30 min before or after tetanization of the perforant path. The reinforcement of LTP was blocked by inhibitors of muscarinergic and beta- adrenergic but not dopaminergic receptors and was d ependent on translation. Through these heterosynaptic associative interacti ons, hippocampal sensory information can be stabilized by amygdaloidal infl uences.