Hippocampal ripples during offline periods predict motor sequence learning.
Pin-Chun Chen1 (firstname.lastname@example.org), Jenny Stritzelberger2, Hajo Hamer2, Bernhard Staresina1; 1University of Oxford, United Kingdom, 2Universitätsklinikum Erlangen, Germany
How does the human brain acquire complex motor skills? Recent studies have revealed that offline rest periods are critical for motor skill learning and implicated the hippocampus in this process. In the declarative memory domain, a key mechanism for offline memory consolidation is the repeated reactivation of neural representations associated with an experience, driven by hippocampal sharp-wave ripples. However, no motor memory studies have recorded directly from hippocampus and therefore the roles of ripples on motor memory remains unknown. Here, we tested the prediction that hippocampal ripples during offline periods contribute to human motor skill learning. Eighteen participants (9 male; age: 31.3 ± 10.16 years) undergoing invasive monitoring for epilepsy surgery performed a standard motor sequence learning task. Specifically, participants were asked to tap a keypress sequence (i.e., 41324) as quickly as possible using their non-dominant hand, in 30-sec blocks interleaved with 30-sec rest periods. We detected hippocampal ripples across the recording session on hippocampal bipolar channels. All statistical tests were performed using linear-mixed effects models in R. Participants showed significant improvement in tapping speed across training (p < .0001). Ripple rates increased during rest compared to active tapping periods (p < .0001). Furthermore, ripple rates during rest increased across training (p = .0329). Finally, ripple rates during rest predicted tapping speed on the subsequent learning block (p = .0122). In sum, increased hippocampal ripples during offline periods may play a functional role in motor skill learning, suggesting the involvement of hippocampus in memory consolidation beyond the declarative memory domain.
Topic Area: LONG-TERM MEMORY: Skill Learning
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April 13–16 | 2024