Deep posteromedial cortical rhythm in dissociation
Sam Vesuna1, Isaac V Kauvar1,2, Ethan Richman1
1Department of Bioengineering, Stanford University, Stanford, CA, USA.
Nature
|September 17, 2020
Summary
Researchers identified a specific brain rhythm linked to dissociation, a disrupted state of experience. This deep posteromedial cortical rhythm, observed in mice and humans, is crucial for understanding and potentially treating dissociation.
Area of Science:
- Neuroscience
- Cognitive Science
- Psychiatry
Background:
- Dissociation disrupts experience, impacting cognition and affect, with unknown neurophysiological underpinnings.
- Advanced imaging allows for cell-type-specific neural activity recording across the mammalian brain.
- Understanding dissociation is vital for both basic science and clinical applications.
Purpose of the Study:
- To investigate the neurophysiology underlying dissociation.
- To establish and characterize a dissociation-like state in mice.
- To identify the molecular and cellular mechanisms of this state.
Main Methods:
- Induced dissociation-like state in mice using ketamine or phencyclidine.
- Utilized large-scale neural imaging and high-density electrophysiological recordings.
- Employed optogenetics for causal manipulation and investigated HCN1 channel function.
- Recorded intracranial stereoencephalography in an epilepsy patient.
Main Results:
- Ketamine/phencyclidine induced a 1-3 Hz rhythm in retrosplenial cortex layer 5 neurons.
- This rhythm involved coupling with thalamic circuitry but uncoupling from other brain regions.
- Optogenetic activation of retrosplenial cortex neurons mimicked dissociation-like behaviors.
- HCN1 pacemakers in retrosplenial cortex were essential for ketamine-induced rhythm and behaviors.
- A similar rhythm in the homologous deep posteromedial cortex was observed in an epilepsy patient during dissociation.
Conclusions:
- A conserved deep posteromedial cortical rhythm underlies dissociation.
- This rhythm involves specific molecular (HCN1), cellular (layer 5 neurons), and network (thalamocortical) properties.
- Findings provide a neurophysiological basis for dissociation and suggest therapeutic targets.
