Brain structural and functional features of individuals with higher controllability of motor imagery

975 

Abstract Submission 

Tomoyo Morita¹, Tomoya Furuta², Gen Miura², Park Jihoon¹, Eiichi Naito¹

¹National Institute of Information and Communications Technology, Osaka, Japan, ²Osaka University, Osaka, Japan

Tomoyo Morita  
National Institute of Information and Communications Technology
Osaka, Japan

Tomoya Furuta  
Osaka University
Osaka, Japan

Gen Miura  
Osaka University
Osaka, Japan

Park Jihoon  
National Institute of Information and Communications Technology
Osaka, Japan

Eiichi Naito  
National Institute of Information and Communications Technology
Osaka, Japan

Motor imagery is a higher-order cognitive brain function that mentally simulates movements without performing the actual physical one (Jeannerod,1994). Although many studies have dealt with motor imagery, neural bases that determine individual differences in motor imagery ability are not well understood. In this study, using magnetic resonance imaging and controllability of motor imagery (CMI) test that can objectively evaluate individual ability to manipulate one's imaginary postures, we elucidated the structural and functional characteristics of the brain that determine individual differences in motor imagery ability.

89 healthy right-handed young adults (53 men: mean age, 22.1 ± 1.7) participated in this study. To evaluate individual's ability to accurately manipulate motor imagery, we used CMI test (Nishida et al. 1986; Naito 1994), in which the participants internally generate, manipulate, and hold one's imaginary body postures from a first-person perspective in response to each of five consecutive verbal instructions regarding movements of body parts (left or right arms, left or right legs, upper body, and head/neck). After the final instruction, participants were asked to perform the final posture by themselves. By evaluating the final posture, whether the participants could manipulate their motor imagery appropriately during the test can be assessed. A T1-weighted image was acquired, with a magnetization-prepared rapid gradient echo (MP-RAGE) sequence using a 3.0-Tesla MRI scanner (Trio Tim; SIEMENS, Germany) and a 32-channel array coil for each participant. We performed voxel-based morphometry (VBM) analysis to examine white and gray matter structures that expand in higher CMI test scorers. We also collected functional images using T2*-weighted gradient echo-planar imaging (EPI), with the same scanner while 33 of 89 participants performed a CMI task and a control task. We identified imagery-related activity during the CMI task when compared with the control task, and also examined brain regions where imagery-related functional coupling with seed regions changes in relation to the CMI test score across participants by conducting a generalized psychophysiological interaction analysis. The study protocol was approved by the Ethics Committee of the NICT. We explained the details of the present study to all participants before the experiment, and they then provided written informed consent. The study was conducted according to the principles and guidelines of the Declaration of Helsinki (1975).

Individuals with higher CMI test scores showed bilateral expansion of white matter regions where the three branches of superior longitudinal fasciculus (SLF I, II, and III) are likely running (Figure 1). When compared with the control task, CMI task activated the bilateral dorsal premotor cortex (PMD) and superior parietal lobule (SPL) that are likely connected by the SLF I and II. Among these regions, the left PMD and/or the right SPL enhance functional coupling with the visual body, somatosensory, and motor/kinesthetic areas in the higher scorers (Figure 2).

This study introduced the CMI test that can objectively evaluate an individual's ability to manipulate one's imaginary postures and has elucidated structural and functional features characterizing the brains of individuals with higher controllability of motor imagery. Structurally, such individuals have expanded frontoparietal white matter that enables fast and rich neural processing of spatial/motor and corporeal information. Functionally, in their brains, the core network of mental simulation (superior frontoparietal network of PMD–SPL), particularly the left PMD and/or the right SPL, likely has top–down access to the visual body, somatosensory, and motor/kinesthetic areas and enhances functional coupling with these for sensory emulation (prediction). This study advanced the understanding of individual difference in motor imagery ability.

Imagery ¹

Motor Behavior Other

BOLD fMRI ²

Cortex

FUNCTIONAL MRI

Motor

STRUCTURAL MRI

Other - Motor Imagery; Individual difference