Memory reactivation in rat medial prefrontal cortex occurs in a subtype of cortical UP state during slow-wave sleep
Abstract
Interaction between hippocampal sharp-wave ripples (SWRs) and UP states, possibly by coordinated reactivation of memory traces, is conjectured to play an important role in memory consolidation. Recently, it was reported that SWRs were differentiated into multiple subtypes. However, whether cortical UP states can also be classified into subtypes is not known. Here, we analysed neural ensemble activity from the medial prefrontal cortex from rats trained to run a spatial sequence-memory task. Application of the hidden Markov model (HMM) with three states to epochs of UP–DOWN oscillations identified DOWN states and two subtypes of UP state (UP-1 and UP-2). The two UP subtypes were distinguished by differences in duration, with UP-1 having a longer duration than UP-2, as well as differences in the speed of population vector (PV) decorrelation, with UP-1 decorrelating more slowly than UP-2. Reactivation of recent memory sequences predominantly occurred in UP-2. Short-duration reactivating UP states were dominated by UP-2 whereas long-duration ones exhibit transitions from UP-1 to UP-2. Thus, recent memory reactivation, if it occurred within long-duration UP states, typically was preceded by a period of slow PV evolution not related to recent experience, and which we speculate may be related to previously encoded information. If that is the case, then the transition from UP-1 to UP-2 subtypes may help gradual integration of recent experience with pre-existing cortical memories by interleaving the two in the same UP state.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 06, 2020
- Source ID
- 10.1098/rstb.2019.0227
Entities
People
- Adrian Ponce-alvarez
- Bruce L. McNaughton
- David R. Euston
- Karim Ali
- Leanna Kalvi
- Masami Tatsuno
- Sonja Grün
- Soroush Malek
Organizations
- Defense Advanced Research Projects Agency
- Institute of Neurosciences, Mental Health and Addiction
- Istituto di Neuroscienze
- Natural Sciences and Engineering Research Council
- Pompeu Fabra University
- RWTH Aachen University
- University of Alberta
- University of California
- University of Lethbridge