Dopaminergic neurons promote hippocampal reactivation and spatial memory persistence.
The hippocampus provides the brain with internal representations of space, but newly-formed spatial representations may degrade with time unless stabilized by additional processes. McNamara and colleagues present compelling evidence of how midbrain dopaminergic neurons strengthen newly-encoded spatial memories related to rewarding and novel experiences .
We found that optogenetic burst stimulation of hippocampal dopaminergic fibers from midbrain neurons in mice exploring novel environments enhanced the reactivation of pyramidal cell assemblies during subsequent sleep/rest. When applied during spatial learning of new goal locations, dopaminergic photostimulation improved the later recall of neural representations of space and stabilized memory performance. These findings reveal that midbrain dopaminergic neurons promote hippocampal network dynamics associated with memory persistence.