Sensorimotor incongruence alters limb perception and movement
Sensorimotor incongruence alters limb perception and movement
Michihiro Osumia, Satoshi Nobusakoa, Takuro Zamab, Megumi Taniguchia, Sotaro Shimadab, Shu Moriokaa,⁎
a Neurorehabilitation Research Center, Kio University, Nara, Japan
Michihiro Osumia, Satoshi Nobusakoa, Takuro Zamab, Megumi Taniguchia, Sotaro Shimadab, Shu Moriokaa,⁎
a Neurorehabilitation Research Center, Kio University, Nara, Japan
b Department of Electronics and Bioinformatics, School of Science and Technology, Meiji University, Kanagawa, Japan
ABSTRACT
Altered limb ownership or heaviness has been observed in patients with hemiplegia, chronic pain, and several other conditions. Although these sensations are thought to be caused by sensorimotor incongruence, few studies have systematically verified this relationship. In addition, it remains unclear whether these subjective sensations affect movement execution. In a psycho- physical experiment, we systematically investigated the relationships between sensorimotor in- tegration and subjective limb perception, such as sense of ownership/heaviness, and verified the relationship between subjective limb perception and movement execution. Thirty-nine healthy participants were enrolled, and a visual feedback delay system was used to systematically evoke sensorimotor incongruence. Participants periodically flexed and extended their wrist while seeing a delayed image of their hand under five delay conditions (0, 150, 250, 350, 600 ms). During wrist movement, electromyography (EMG) activity in flexor carpi radialis (FCR) was recorded. Also, to analyze the change in muscle activity and movement speed, the values of integral and peak frequency were calculated. To record changes in the subjective limb perception of the altered limb ownership and heaviness, we used a 7-point Likert scale for each participant. We found that altered ownership and heaviness increased with increasing feedback delay. Also, muscle activity and movement speed decreased with visual feedback delay. There was no sig- nificant correlation between subjective altered limb perception (i.e., altered limb ownership and heaviness) and muscle activity or movement speed. We systematically demonstrated that limb ownership, heaviness, muscle activation and movement speed were altered by sensorimotor in- congruence. However, our study did not reveal the relationships between these factors. These results indicate the existence of different mechanisms governing subjective limb perception and movement execution. In the future, we should consider rehabilitation methods to improve sen- sorimotor incongruence.
Altered limb ownership or heaviness has been observed in patients with hemiplegia, chronic pain, and several other conditions. Although these sensations are thought to be caused by sensorimotor incongruence, few studies have systematically verified this relationship. In addition, it remains unclear whether these subjective sensations affect movement execution. In a psycho- physical experiment, we systematically investigated the relationships between sensorimotor in- tegration and subjective limb perception, such as sense of ownership/heaviness, and verified the relationship between subjective limb perception and movement execution. Thirty-nine healthy participants were enrolled, and a visual feedback delay system was used to systematically evoke sensorimotor incongruence. Participants periodically flexed and extended their wrist while seeing a delayed image of their hand under five delay conditions (0, 150, 250, 350, 600 ms). During wrist movement, electromyography (EMG) activity in flexor carpi radialis (FCR) was recorded. Also, to analyze the change in muscle activity and movement speed, the values of integral and peak frequency were calculated. To record changes in the subjective limb perception of the altered limb ownership and heaviness, we used a 7-point Likert scale for each participant. We found that altered ownership and heaviness increased with increasing feedback delay. Also, muscle activity and movement speed decreased with visual feedback delay. There was no sig- nificant correlation between subjective altered limb perception (i.e., altered limb ownership and heaviness) and muscle activity or movement speed. We systematically demonstrated that limb ownership, heaviness, muscle activation and movement speed were altered by sensorimotor in- congruence. However, our study did not reveal the relationships between these factors. These results indicate the existence of different mechanisms governing subjective limb perception and movement execution. In the future, we should consider rehabilitation methods to improve sen- sorimotor incongruence.
和訳：片麻痺、慢性疼痛および他のいくつかの状態の患者では、四肢の身体所有感または重さの変化が観察されている。これらの感覚は知覚-運動の不協和によって引き起こされると考えられているが、この関係を体系的に検証した研究はほとんどない。さらに、これらの主観的感覚が運動の実行に影響するかどうかは依然として不明である。心理物理的実験によって、知覚-運動不協和と身体所有感/重量感のような主観的知覚の関係性を系統的に調査し、さらに主観的四肢知覚と運動実行の関係を検証した。 39人の健康な参加者が登録され、視覚的フィードバック遅延システムが知覚-運動不協和を体系的に誘発するために使用された。参加者は、5つの遅延条件（0,150,250,350,600ms）で手の画像が遅延しているのを見ながら、周期的に手関節屈曲と伸展を繰り返した。手関節運動中、橈側手根屈筋（FCR）における筋電図（EMG）活動が記録された。また、筋活動および運動速度の変化を分析するために、積分およびピーク頻度の値を計算した。変更された四肢の所有感および重さの主観的知覚における変化を記録するために、各参加者に7ポイントのリッカート尺度を使用した。フィードバック遅延の増加に伴い、身体所有感の変容と重量が増加することがわかった。また、筋活動および運動速度は、視覚フィードバック遅延とともに減少した。主観的な四肢の知覚（すなわち、四肢の所有感および重さの変化）および筋活動または運動速度の間には、有意な相関はなかった。我々は、四肢の所有感、重さ、筋肉の活性化および運動速度が知覚運動の不協和によって変化したことを体系的に実証した。しかし、我々の研究は、これらの要因間の関係を明らかにしなかった。これらの結果は、主観的な四肢の所有感および運動実行を支配する異なるメカニズムの存在を示している。今後は知覚運動の不協和を改善するためのリハビリテーション手法を検討すべきである。
コメント:運動意図と視覚情報のフィードバックの不一致はあると思うが、運動遂行中は実運動による固有感覚情報のフィードバックがあるのを考えると、それだけ視覚情報は運動に大きな影響があると言えるか。筋活動の低下が起きる点は面白い。不一致があると努力的に筋活動が増えてしまうような印象もあるが低下するという結果(円滑さや協調性とは別に。筋出力だけあがってしまいそう)。映像遅延装置の大きな工夫はあるが、あとは質問紙と筋電だけというシンプルな実験系で明確にできた事実があるのは、見習いたいところ。
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