Investigating the effects of chronic stress on hippocampal representations, synaptic connectivity and learning.
Final Report Abstract
Stress exposure impairs brain structure and function, resulting in cognitive deficits and increased risk for psychiatric disorders such as depression, schizophrenia, anxiety and post-traumatic stress disorder. In particular, stress exposure affects function and structure of hippocampal CA1 leading to impairments in episodic memory. We combined two modalities of deep-brain optical imaging in mice undergoing repeated stress to investigate the link between changes in activity patterns and structural plasticity of dorsal CA1 pyramidal neurons and hippocampal-dependent learning and memory. By imaging activity patterns, we found increase in activity and loss of temporal organization followed by disruption in temporal and spatial coding. By tracking dynamics of dendritic spines, we found decrease in spinogenesis followed by decrease in spine stability. In addition, acute stress led to stabilization of the spines born in temporal proximity to the stressful event. Our data imply that repeated stress leads to increased activity followed by loss of connectivity and subsequent weakening of temporal and spatial coding associated to milder impairment in learning, while acute stress leads to temporary stabilization of connectivity associated to more severe impairment in learning.
Publications
- Aberrant structural synaptic dynamics precede disorganization of temporal and spatial coding in the hippocampus upon repeated stress exposure. bioRxiv 2020.11.30.403972.
Alireza Chenani et al.
(See online at https://doi.org/10.1101/2020.11.30.403972)
