Adverse effects of chronic stress include anxiety, depression, and memory deficits. Some of these stress-induced behavioural deficits are mediated by impaired hippocampal function. Much of our current understanding about how stress affects the hippocampus has been derived from post-mortem analyses of brain slices at fixed time points. Consequently, neural signatures of an ongoing stressful experiences in the intact brain of awake animals and their links to later hippocampal dysfunction remain poorly understood. Further, no information is available on the impact of stress on sharp-wave ripples (SPW-Rs), high frequency oscillation transients crucial for memory consolidation. Here, we used in vivo tetrode recordings to analyze the dynamic impact of 10 days of immobili-zation stress on neural activity in area CA1 of mice. While there was a net decrease in pyramidal cell activity in stressed animals, a greater fraction of CA1 spikes occurred specifically during sharp-wave ripples, resulting in an increase in neuronal synchrony. After repeated stress some of these alterations were visible during rest even in the absence of stress. These findings offer new insights into stress-induced changes in ripple-spike interactions and mechanisms through which chronic stress may interfere with subsequent information processing
Bibliographical noteFunding Information:
We thank all members of the CBP laboratory for their support, the Advanced Manufacturing Support Team, RIKEN Center for Advanced Photonics for their assistance in microdrive production and Lalitha Krishnan for assistance with figure generation. We also thank Dr. Kazumasa Z. Tanaka for input and support. This works was supported by Grant-in-Aid for Scientific Research from MEXT ( 19H05646 ; T.J.M), Grant-in-Aid for Scientific Research on Innovative Areas from MEXT ( 19H05233 ; T.J.M) and RIKEN BSI and CBS (T.J.M). S.C. is supported by funds from TIFR and Department of Atomic Energy, Government of India . We dedicate this work to the memory of Bruce S. McEwen.
© 2021 The Authors
- Pyramidal Cells