Responsiveness of dentate neurons generated throughout adult life is associated with resilience to cognitive aging

Abstract

Brain and cognition change with age, and although patterns of decline are evident at the population level, the rates of change differ among individuals as well as across brain regions and cognitive domains (Gray & Barnes, 2015; Nyberg, Lovden, Riklund, Lindenberger, & Backman, 2012). Indeed, some old individuals exhibit cognitive abilities similar to those of younger ones (optimal/successful aging) whereas others show a clear and substantial cognitive decline without signs of pathologies (suboptimal/accelerated aging). Episodic memory is particularly sensitive to aging, and investigations conducted so far both in humans and in animal models have revealed that the preservation of episodic memory abilities is correlated with the structural and functional integrity of the hippocampal

Cognitive Reserve in Model Systems for Mechanistic Discovery: The Importance of Longitudinal Studies

“…For example, aging and AD are associated with synaptic loss and local circuits may invoke plastic processes such as increasing the strength of remaining synapses (Barnes and McNaughton, 1980;Foster et al, 1991;Scheff et al, 1996;Chen and Hillman, 1999;Burke and Barnes, 2006;Neuman et al, 2015). Behavioral discrepancies are linked to plastic properties that depend on learning-induced and activitydependent signaling cascades (i.e., CREB phosphorylation) to influence cell excitability Foster, 2019;Montaron et al, 2020;Oh and Disterhoft, 2020). Task-specific changes in local amygdala electroencephalogram recordings, selectively within the beta range (15-30 Hz), developed with training, selectively in aged rats, possibly as an adaptive mechanism to preserve learning (Samson et al, 2017).…”

The unique plasticity of hippocampal adult‐born neurons: Contributing to a heterogeneous dentate

“…Recent study in aged males used a variety of thymidine analogs to birthdate developmentally born neurons or adult‐born neurons born 4, 10, or 19 months prior to water maze training. Learning resulted in zif268 expression in adult‐born neurons at all time points but not in developmentally born neurons (Montaron, Charrier, Blin, Garcia, & Abrous, 2020). Although these particular studies were confounded by ontogenetic age of the cells (for full discussion see [Snyder, 2019]), cumulatively they suggest that adult hippocampal neurogenesis ultimately results in a DG populated by heterogeneous neurons.…”

A Baldwin interpretation of adult hippocampal neurogenesis: from functional relevance to physiopathology

“…experimentally mimicked by most stress protocols, is very favorable to the development of mental disorders in the adult. Indeed, strong consistent data suggest that deficits in AHN are involved in most mental disorders that do not originate solely in neurodevelopmental dysfunctions: it is involved in anxiety disorders, post-traumatic stress disorder [15], addictions [16][17][18], and in some dysfunctions in the aging brain [19][20][21], but not in developmental disorders such as ADHD and autism spectrum disorder, or in schizophrenia spectrum and psychotic disorders.…”