Motor imagery-based skill acquisition disrupted following rTMS of the inferior parietal lobule

Abstract

Motor imagery (MI), the mental rehearsal of motor tasks, has promise as a therapy in post-stroke rehabilitation. The potential effectiveness of MI is attributed to the facilitation of plasticity in numerous brain regions akin to those recruited for physical practice. It is suggested, however, that MI relies more heavily on regions commonly affected post-stroke, including left hemisphere parietal regions involved in visuospatial processes. However, the impact of parietal damage on MI-based skill acquisition that underlies rehabilitation remains unclear. Here, we examine the contribution of the left inferior parietal lobule (IPL) to MI using inhibitory transcranial magnetic stimulation (TMS) and an MI-based implicit sequence learning (ISL) paradigm. Participants (N = 27) completed the MI-based ISL paradigm after receiving continuous theta burst stimulation to the left IPL (TMS), or with the coil angled away from the scalp (sham). Reaction time differences (dRT) and effect sizes between implicit and random sequences assessed success of MI-based learning. Mean dRT for the sham group was 36.1 ± 28.2 ms (d = 0.71). Mean dRT in the TMS group was 7.7 ± 38.5 ms (d = 0.11). These results indicate that inhibition of the left IPL impaired MI-based learning. We conclude that the IPL and likely the visuospatial processes it mediates are critical for MI performance and thus MI-based skill acquisition or learning. Ultimately, these findings have implications for the use of MI in post-stroke rehabilitation.

Experience modulates motor imagery‐based brain activity

“…() when comparing brain activation during MI before and after novices trained on a shooting task. Thus, while there is undoubtedly brain activation specific to processes that underlie MI (Hétu et al ., ; Kraeutner et al ., ; Oostra et al ., ; Ptak et al ., ), the diffuse patterns of activity generally observed during MI may not be purely indicative of a difference between MI and physical practice. Instead, we suggest that these patterns are also influenced by the degree to which the user is experienced with the skill.…”

Damage to Fronto-Parietal Networks Impairs Motor Imagery Ability after Stroke: A Voxel-Based Lesion Symptom Mapping Study

“…Our results indicate that lesions in this region of the long associative fibers mediating the integration of visual and sensory information for motor planning and control, are associated with poor motor imagery vividness. Kraeutner et al ( 2015a ) recently demonstrated the importance of the left inferior parietal cortex (IPL) for MI performance. A preserved function of the IPL was shown to be critical for learning the cognitive aspects of a skill via MI practice.…”

Motor Imagery-Based Rehabilitation: Potential Neural Correlates and Clinical Application for Functional Recovery of Motor Deficits after Stroke

“…Further, many neuroimaging studies have established the presence of MI-induced PPC activity, as well as MI deficits following PPC damage [7, 56]. Parietal regions such as the inferior parietal lobule [57], the supramarginal gyrus [58], and the superior parietal lobule [59] have also been implicated in MI tasks. Highlighting the necessity of intact parietal structures for vivid MI, a 2016 systematic review indicated that subjects with parietal lobe damage were the most substantially impaired in their ability to perform MI [27].…”