| Autor: |
Tatsuno M; Department of Neuroscience, University of Lethbridge, Lethbridge, T1K 3M4 Alberta, Canada., Malek S; Department of Neuroscience, University of Lethbridge, Lethbridge, T1K 3M4 Alberta, Canada., Kalvi L; Department of Neuroscience, University of Lethbridge, Lethbridge, T1K 3M4 Alberta, Canada.; Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, T6G 2H7 Alberta, Canada., Ponce-Alvarez A; Center for Brain and Cognition, Computational Neuroscience Group, Pompeu Fabra University, 08005 Barcelona, Spain., Ali K; Department of Neuroscience, University of Lethbridge, Lethbridge, T1K 3M4 Alberta, Canada., Euston DR; Department of Neuroscience, University of Lethbridge, Lethbridge, T1K 3M4 Alberta, Canada., Gruen S; Institute of Neuroscience and Medicine (INM-6), Institute for Advanced Simulation (IAS-6) and JARA Brain Institute I (INM-10), Jülich Research Center, 52425 Jülich, Germany.; Theoretical Systems Neurobiology, RWTH Aachen University, 52056 Aachen, Germany., McNaughton BL; Department of Neuroscience, University of Lethbridge, Lethbridge, T1K 3M4 Alberta, Canada.; Department of Neurobiology and Behaviour, University of California, Irvine, CA 92697, USA. |
| Abstrakt: |
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. This article is part of the Theo Murphy meeting issue 'Memory reactivation: replaying events past, present and future'. |
