Memory consolidation during sleep is thought to depend on the coordinated interplay between cortical slow waves, thalamocortical sleep spindles and hippocampal ripples, but direct evidence is lacking. Here, we implemented real-time closed-loop deep brain stimulation in human prefrontal cortex during sleep and tested its effects on sleep electrophysiology and on overnight consolidation of declarative memory. Synchronizing the stimulation to the active phases of endogenous slow waves in the medial temporal lobe (MTL) enhanced sleep spindles, boosted locking of brain-wide neural spiking activity to MTL slow waves, and improved coupling between MTL ripples and thalamocortical oscillations. Furthermore, synchronized stimulation enhanced the accuracy of recognition memory. By contrast, identical stimulation without this precise time-locking was not associated with, and sometimes even degraded, these electrophysiological and behavioral effects. Notably, individual changes in memory accuracy were highly correlated with electrophysiological effects. Our results indicate that hippocampo-thalamocortical synchronization during sleep causally supports human memory consolidation.
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http://dx.doi.org/10.1038/s41593-023-01324-5 | DOI Listing |
J Comput Neurosci
December 2024
Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, 19104, PA, USA.
Traveling waves of neuronal spiking activity are commonly observed across the brain, but their intrinsic function is still a matter of investigation. Experiments suggest that they may be valuable in the consolidation of memory or learning, indicating that consideration of traveling waves in the presence of plasticity might be important. A possible outcome of this consideration is that the synaptic pathways, necessary for the propagation of these waves, will be modified by the waves themselves.
View Article and Find Full Text PDFHippocampus
January 2025
Center for Systems Neuroscience, Boston University, Boston, Massachusetts, USA.
In keeping with the historical focus of this special issue of Hippocampus, this paper reviews the history of my development of the SPEAR model. The SPEAR model proposes that separate phases of encoding and retrieval (SPEAR) allow effective storage of multiple overlapping associative memories in the hippocampal formation and other cortical structures. The separate phases for encoding and retrieval are proposed to occur within different phases of theta rhythm with a cycle time on the order of 125 ms.
View Article and Find Full Text PDFFront Behav Neurosci
December 2024
Department of Civil, Environmental, and Construction Engineering, Texas Tech University, Lubbock, TX, United States.
The Morris Water Maze (MWM) is the most commonly used assay for evaluating learning and memory in laboratory mice. Despite its widespread use, contemporary reviews have highlighted substantial methodological variation in experimental protocols and that the associated testing procedures are acutely (each trial) and chronically (testing across days) stressful; stress impairs attention, memory consolidation and the retrieval of learned information. Moreover, the interpretation of behavior within the MWM is often difficult because of wall hugging, non-spatial swim strategies, floating, and jumping off the escape platform.
View Article and Find Full Text PDFSleep
December 2024
Department of Biology, Stanford University, Stanford, CA 94305-5020, USA.
Down syndrome (DS) is a common genetic condition affecting people worldwide. It involves cognitive disabilities for which there are no drug therapies. The Ts65Dn mouse model of DS shows cognitive impairment due to a reduction in neuron number and connectivity as well as excessive neuronal activity, as GABA antagonist treatment restores memory in these mice.
View Article and Find Full Text PDFJ Acoust Soc Am
December 2024
Division of Humanities, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
In perceptual studies, musicality and pitch aptitude have been implicated in tone learning, while vocabulary size has been implicated in distributional (segment) learning. Moreover, working memory plays a role in the overnight consolidation of explicit-declarative L2 learning. This study examines how these factors uniquely account for individual differences in the distributional learning and consolidation of an L2 tone contrast, where learners are tonal language speakers, and the training is implicit.
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