Structural Gray Matter Changes in the Hippocampus and the Primary Motor Cortex on An-Hour-to-One- Day Scale Can Predict Arm-Reaching Performance Improvement

Abstract

Recent studies have revealed rapid (e.g., hours to days) training-induced cortical structural changes using magnetic resonance imaging (MRI). Currently, there is great interest in studying how such a rapid brain structural change affects behavioral improvement. Structural reorganization contributes to memory or enhanced information processing in the brain and may increase its capability of skill learning. If the gray matter (GM) is capable of such rapid structural reorganization upon training, the extent of volume increase may characterize the learning process. To shed light on this issue, we conducted a case series study of 5-day visuomotor learning using neuroanatomical imaging, and analyzed the effect of rapid brain structural change on motor performance improvement via regression analysis. Participants performed an upper-arm reaching task under left-right mirror-reversal for five consecutive days; T1-weighted MR imaging was performed before training, after the first and fifth days, and 1 week and 1 month after training. We detected increase in GM volume on the first day (i.e., a few hours after the first training session) in the primary motor cortex (M1), primary sensory cortex (S1), and in the hippocampal areas. Notably, regression analysis revealed that individual differences in such short-term increases were associated with the learning levels after 5 days of training. These results suggest that GM structural changes are not simply a footprint of previous motor learning but have some relationship with future motor learning. In conclusion, the present study provides new insight into the role of structural changes in causing functional changes during motor learning.

Cueing motor memory reactivation during NREM sleep engenders learning-related changes in precuneus and sensorimotor structures

“…We chose to focus specifically on a procedural memory task because the importance of sleep in procedural memory consolidation is well established 16,17 . Furthermore procedural memory task improvements 18 and the associated structural changes 19 have been shown to persist over time, with the same being true for the TMR effects 11 . Our participants were trained on two motor sequences in a Serial Reaction Time Task (SRTT).…”

Coherent waves of myelin plasticity during motor-skill learning

“…This is in keeping with the role of the EC as the interface between the hippocampus and cortex, with the latter sharing limited direct connections (Burman, 2019; Maller et al, 2019). Contemporaneous volumetric increases have been observed in the sensorimotor cortex and the hippocampus during 5 days of visuo-motor training (Kodama et al, 2018), but this is the first evidence of an M1-EC-hippocampal circuit active during motor learning and underlines the potential versatility of quantitative MRI markers in mapping skill acquisition and recovery over time.…”

Multimodal imaging of brain reorganization in hearing late learners of sign language

“…In contrast to the initial changes in functional activity, the change in GMV did not occur rapidly (between TP0 and TP1), but was more prolonged in time, with the peak at the end of the PJM course. A number of studies have shown that GMV changes can be detected as early as within a few days or even hours of training as a result of improving, for example, visuomotor skills (e.g., Driemeyer et al, 2008; Kodama, Ono, Yamashita, Ebata, & Liu, 2018; Landi, Baguear, & Della‐Maggiore, 2011) or learning new colors (Kwok et al, 2011). We extend these findings by showing that cognitively demanding and time‐consuming L2 acquisition also results in GMV increases after just a few months of learning.…”