A functional hypothesis for adult hippocampal neurogenesis: Avoidance of catastrophic interference in the dentate gyrus

Abstract

The dentate gyrus is part of the hippocampal memory system and special in that it generates new neurons throughout life. Here we discuss the question of what the functional role of these new neurons might be. Our hypothesis is that they help the dentate gyrus to avoid the problem of catastrophic interference when adapting to new environments. We assume that old neurons are rather stable and preserve an optimal encoding learned for known environments while new neurons are plastic to adapt to those features that are qualitatively new in a new environment. A simple network simulation demonstrates that adding new plastic neurons is indeed a successful strategy for adaptation without catastrophic interference.

CD4-Positive T Lymphocytes Provide a Neuroimmunological Link in the Control of Adult Hippocampal Neurogenesis

“…Our present data suggest that CD4 depletion causes deficits in such reversal situation only. This would be in line with our hypothesis that new neurons are not needed for learning and memory per se, but to avoid catastrophic interference in relearning situations (13). SCID and nude mice that lack both B and T cells showed impairments during both acquisition and reversal of the water maze task (22).…”

“…The exact functional relevance of the newborn neurons in the DG is not yet fully understood (9 -11), but several lines of evidence point to a contribution of the new neurons to long-term adaptation (12,13). Physiological and certain learning stimuli robustly induce adult hippocampal neurogenesis (14 -17).…”

Human experience seeking correlates with hippocampus volume: Convergent evidence from manual tracing and voxel-based morphometry

“…Neurogenesis has been demonstrated in the hippocampus (Eriksson et al, 1998), and this process can be behaviorally modulated (Kempermann and Gage, 1998;Gage, 2002). Wiskott et al (2006) have hypothesized that frequent exposure to novel environments causes an increase in hippocampal neurogenesis.…”

Interaction between Neurogenesis and Hippocampal Memory System: New Vistas

“…In particular, the "catastrophic" interference in computational networks is the phenomenon in which successive patterns of incoming stimuli overwrite the existing patterns to the point of the latter being unrecognizable (McClelland et al 1995). Such a computational procedure was thought to resemble a physiological process with newer memories erasing or degrading previously acquired memory traces in the brain (discussed in Wiskott et al 2006). One computational method to solve the pattern overlap problem and, hence, avoid memory interference is to store patterns in distributed (sparse) networks.…”