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Spontaneous Infraslow Fluctuations Modulate Hippocampal EPSP-PS Coupling
Michael B Dash1,2, Stephen Ajayi2, Lynde Folsom2
1Department of Psychology, Middlebury College, Middlebury, VT 05753.
Eneuro
|January 20, 2018
Summary
Spontaneous brain activity (SBA) influences hippocampal responses. Infraslow SBA fluctuations modulate neuronal excitability, affecting sensory selection and information processing by altering how the brain responds to identical inputs.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Systems Neuroscience
Background:
- Trial-to-trial variability is common in brain function.
- Spontaneous brain activity (SBA) may underlie this variability by altering neuronal excitability.
- Hippocampal function is crucial for memory and cognition.
Purpose of the Study:
- To investigate the relationship between spontaneous brain activity and hippocampal evoked responses in freely-behaving rats.
- To determine if SBA fluctuations are coordinated and influence neuronal output heterogeneity.
- To understand the role of infraslow SBA in modulating information processing.
Main Methods:
- Recording hippocampal evoked responses in male rats under constant medial perforant path stimulation.
- Analyzing spontaneous brain activity (SBA) in the 4-second window preceding stimulation.
- Quantifying band-limited power (BLP) in low (0.5-9 Hz) and high (40.25-100 Hz) frequencies.
- Examining infraslow (0.005-0.02 Hz) fluctuations in SBA and their correlation with evoked response parameters (fEPSP slope, population spike amplitude).
Main Results:
- Extensive variability in hippocampal evoked responses was observed despite constant stimulation.
- Increased low- and high-frequency SBA power preceded decreased fEPSP slope and increased population spike (PS) amplitude.
- Infraslow SBA fluctuations were coordinated and exhibited distinct phase relationships with fEPSP slope and PS amplitude changes.
- SBA dynamically modulated EPSP-PS coupling, leading to heterogeneous hippocampal outputs from identical inputs.
Conclusions:
- Infraslow spontaneous brain activity plays a critical role in shaping hippocampal output variability.
- SBA dynamically alters neuronal excitability and EPSP-PS coupling, influencing information processing and sensory selection.
- Endogenous neuronal activity, particularly infraslow SBA, is fundamental for modulating the brain's response to stimuli.
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