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Instantaneous amplitude and shape of postrhinal theta oscillations differentially encode running speed
Megha Ghosh1, Benjamin E Shanahan2, Sharon C Furtak1
1Department of Psychology.
Behavioral Neuroscience
|February 11, 2021
Summary
Postrhinal cortex theta oscillations exhibit temporal asymmetry, similar to the hippocampus. Individual theta cycle amplitude and shape changes are poorly correlated and differentially encode running speed.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
Background:
- Hippocampal theta oscillations display a temporally asymmetric waveform.
- The extension of this theta asymmetry to other brain regions involved in spatial navigation and memory remains unclear.
Purpose of the Study:
- To investigate the temporal waveform shape of theta oscillations in the postrhinal cortex.
- To determine if theta asymmetry in the postrhinal cortex is correlated with amplitude and running speed.
Main Methods:
- Utilized established and improved cycle-by-cycle analysis techniques.
- Analyzed instantaneous amplitude and temporal asymmetry of postrhinal theta cycles.
Main Results:
- Postrhinal cortex theta waveforms are temporally asymmetric, with a longer falling phase than the rising phase.
- Rapid changes in theta amplitude and asymmetry were poorly correlated, suggesting independent mechanisms.
- Instantaneous theta amplitude and asymmetry differentially encoded running speed, with asymmetry plateauing at medium speeds.
Conclusions:
- Theta waveform shape and amplitude in the postrhinal cortex may be regulated by partially independent mechanisms.
- A single-cycle approach is crucial for understanding the generation and behavioral relevance of cortical theta rhythms.
