More than Memory: The Role of the Hippocampus in Modulating Behaviour, Future Planning, and Stress Regulation
Sue Becker
McMaster University

The hippocampus plays a crucial role in the formation and recall of episodic and contextual memories. More recent work also implicates this brain region in the contextual guidance of action selection, planning for the future, and modulating responses to stress. One factor that may contribute vitally to these functions is ongoing adult neurogenesis. However, a variety of lifestyle factors including chronic stress and alcohol abuse are neurotoxic to hippocampal tissue. In adult rodents, even a few days of stress or alcohol bingeing disrupts the ongoing production of neurons in the hippocampus. Moreover, reduced neurogenesis is associated with selective deficits on high interference memory tasks and an increased vulnerability to subsequent chronic stress exposure. Consistent with the rodent literature, in healthy young adults and in a clinically depressed sample, we find that high stress/depression scores and self-reported early onset alcohol bingeing are associated with deficits on high interference memory tasks. On the other hand, aerobic exercise renormalizes stress and depression scores and boosts neurogenesis-dependent memory. Preliminary data suggest that yoga may have similar benefits. Moreover, in rodents, we find that exercise combined with an anti-oxidant and anti-inflammatory rich dietary supplement ameliorates the effects of chronic stress, reducing structural damage to the hippocampus, loss of neurogenesis and anhedonia. The combination of exercise and diet holds great promise for promoting healthy aging and treating stress-related psychiatric disorders and dementia.