Facilitated hand proprioceptive processing in paraplegics with long-term wheelchair sports training

2531 

Abstract Submission 

Eiichi Naito^1,2, Tomoyo Morita^1,2

¹CiNet, NICT, Suita, Japan, ²Graduate School of Frontier Biosciences, Osaka University, Suita, Japan

Eiichi Naito  
CiNet, NICT|Graduate School of Frontier Biosciences, Osaka University
Suita, Japan|Suita, Japan

Tomoyo Morita  
CiNet, NICT|Graduate School of Frontier Biosciences, Osaka University
Suita, Japan|Suita, Japan

Previous studies have revealed drastic changes in motor processing in individuals with congenital or acquired limb deficiencies and dysfunction. However, little is known about whether their brains also exhibit characteristic proprioceptive processing. This study examined brain activity characteristics in four individuals with congenital or acquired paraplegia who had long-term wheelchair sports training (paraplegic group), when they passively experienced a right-hand movement (passive task) and when they actively performed a right-hand motor task (active task), compared to 37 able-bodied individuals (control group).

One participant with congenital paraplegia (P1) and three participants with acquired paraplegia (P2, P3, and P4) participated in this study. P1 was an active, top wheelchair racing Paralympian, aged 30 years. She began racing at the age of eight and underwent long-term wheelchair racing training. She won a total of 19 medals in six consecutive Summer Paralympic Games as of 2021. P2, P3, and P4 were not top athletes at the level of participant P1, but had more than 30 years of leg non-use period and long-term wheelchair sports training. P2 had paraplegia at the age of one and had 42 years of experience in wheelchair basketball and four years of experience in wheelchair table tennis. P3 had paraplegia at the age of 17 and had 27 years of experience in wheelchair table tennis. He was a Paralympian in Río de Janeiro. P4 had paraplegia at the age of 21 and had 31 years of experience in wheelchair basketball, 9 years of experience in wheelchair marathon, and 9 years of experience in wheelchair fencing. P1, P3, and P4 had no somatic sensations (light touch and pin prick) in their lower limbs and had complete immobility. P2 had complete immobility of his lower limbs; nonetheless, there were somatic sensations (light touch and pinprick). P1, P3, and P4 were right-handed, and P2 was ambidextrous. For the control participants, we recruited age-matched right-handed able-bodied adults (n = 37; 25 females) aged 37.4 ± 10.9 years (range 25–59 years). They had experience in various sports since their school days, but none of them were athletes participating in a particular sport. None of the able-bodied participants had a history of neurological, psychiatric, or movement disorders. Functional MRI images were acquired using T2*-weighted gradient echo-planar imaging (EPI) sequences with a 3.0-Tesla MRI scanner (MAGNETOM Trio Tim; Siemens, Germany) and a 32-channel array coil when the paraplegic and able-bodied individuals performed the passive and active tasks. We performed both contrast analysis and region-of-interest analysis (p < 0.05 corrected). The study protocol was approved by the Ethics Committee of the National Institute of Information and Communications Technology (NICT) and the MRI Safety Committee of the Center for Information and Neural Networks (CiNet; no. 2003260010). The details of the experiment were explained to each participant before the experiment, after which they provided written informed consent. This study was conducted in accordance with the principles and guidelines of the Declaration of Helsinki (1975).

The paraplegic group activated the foot section of the left primary motor cortex (M1) during the passive task, which was deactivated in the control group (Figure 1). Compared with the control group, the paraplegic group showed significantly greater activity in the inferior frontoparietal proprioceptive network (right inferior parietal lobule, area 44, and bilateral insula) during the passive task (Figure 2). None of the regions showed significantly greater activity in the paraplegic group during the active task. Similarly, no regions showed significantly greater activity in the control group for either task (Morita and Naito 2022).

This study demonstrated the facilitation of hand proprioceptive processing in the brains of paraplegic individuals with long-term wheelchair sports training.

Activation (eg. BOLD task-fMRI) ²

Perception: Tactile/Somatosensory ¹

Development

Motor

MRI

Plasticity

Somatosensory