Behavioral reinforcement of long-term potentiation is impaired in aged rats with cognitive deficiencies.

Behavioral stimuli with emotional/motivational content can reinforce long-term potentiation in the dentate gyrus, if presented within a distinct time window. A similar effect can be obtained by stimulating the basolateral amygdala, a limbic structure related to emotions. We have previously shown that aging impairs amygdala-hippocampus interactions during long-term potentiation. In this report we show that behavioral reinforcement of long-term potentiation is also impaired in aged rats with cognitive deficits. While among young water-deprived animals drinking 15 min after induction of long-term potentiation leads to a significant prolongation of potentiation, cognitively impaired aged rats are devoid of such reinforcing effects. In contrast, a slight but statistically significant depression develops after drinking in this group of animals. We suggest that an impaired mechanism of emotional/motivational reinforcement of synaptic plasticity might be functionally related to the cognitive deficits shown by aged animals.