
@article {93057,
	title = {Stress enhances hippocampal neuronal synchrony and alters ripple-spike interaction.},
	journal = {Neurobiol Stress},
	volume = {14},
	year = {2021},
	month = {2021 May},
	pages = {100327},
	abstract = {<p>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 tetrode recordings to analyze the dynamic impact of 10 days of immobilization 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.</p>
},
	issn = {2352-2895},
	doi = {10.1016/j.ynstr.2021.100327},
	author = {Tomar, Anupratap and Polygalov, Denis and Chattarji, Sumantra and McHugh, Thomas J}
}
@article {909,
	title = {The dynamic impact of repeated stress on the hippocampal spatial map.},
	journal = {Hippocampus},
	volume = {25},
	year = {2015},
	month = {2015 Jan},
	pages = {38-50},
	abstract = {<p>Stress alters the function of many physiological processes throughout the body, including in the brain. A neural circuit particularly vulnerable to the effects of stress is the hippocampus, a key component of the episodic and spatial memory system in both humans and rodents. Earlier studies have provided snapshots of morphological, molecular, physiological and behavioral changes in the hippocampus following either acute or repeated stress. However, the cumulative impact of repeated stress on in vivo hippocampal physiology remains unexplored. Here we report the stress-induced modulation of the spatially receptive fields of the hippocampal CA1 {\textquoteright}place cells{\textquoteright} as mice explore familiar and novel tracks after 5 and 10 days of immobilization stress. We find that similar to what has been observed following acute stress, five days of repeated stress results in decreased excitability of CA1 pyramidal cells. Following ten days of chronic stress, however, this decreased hippocampal excitability is no longer evident, suggesting adaptation may have occurred. In addition to these changes in neuronal excitability, we find deficient context discrimination, wherein both short-term and chronic stress impair the ability of the hippocampus to unambiguously distinguish novel and familiar environments. These results suggest that a loss of network flexibility may underlie some of the behavioral deficits accompanying chronic stress.</p>
},
	keywords = {Animals, Behavior, Animal, CA1 Region, Hippocampal, Discrimination (Psychology), Generalization (Psychology), Male, Mice, Mice, Inbred C57BL, Spatial Memory, Stress, Psychological, Time Factors},
	issn = {1098-1063},
	doi = {10.1002/hipo.22348},
	author = {Tomar, Anupratap and Polygalov, Denis and Chattarji, Sumantra and McHugh, Thomas J}
}
