title: Quantitative evaluation of human cerebellum-dependent motor learning through prism adaptation of hand-reaching movement.
abstract: The cerebellum plays important roles in motor coordination and learning. However, motor learning has not been quantitatively evaluated clinically. It thus remains unclear how motor learning is influenced by cerebellar diseases or aging, and is related with incoordination. Here, we present a new application for testing human cerebellum-dependent motor learning using prism adaptation. In our paradigm, the participant wearing prism-equipped goggles touches their index finger to the target presented on a touchscreen in every trial. The whole test consisted of three consecutive sessions: (1) 50 trials with normal vision (BASELINE), (2) 100 trials wearing the prism that shifts the visual field 25° rightward (PRISM), and (3) 50 trials without the prism (REMOVAL). In healthy subjects, the prism-induced finger-touch error, i.e., the distance between touch and target positions, was decreased gradually by motor learning through repetition of trials. We found that such motor learning could be quantified using the "adaptability index (AI)", which was calculated by multiplying each probability of [acquisition in the last 10 trials of PRISM], [retention in the initial five trials of REMOVAL], and [extinction in the last 10 trials of REMOVAL]. The AI of cerebellar patients less than 70 years old (mean, 0.227; n = 62) was lower than that of age-matched healthy subjects (0.867, n = 21; p < 0.0001). While AI did not correlate with the magnitude of dysmetria in ataxic patients, it declined in parallel with disease progression, suggesting a close correlation between the impaired cerebellar motor leaning and the dysmetria. Furthermore, AI decreased with aging in the healthy subjects over 70 years old compared with that in the healthy subjects less than 70 years old. We suggest that our paradigm of prism adaptation may allow us to quantitatively assess cerebellar motor learning in both normal and diseased conditions.
authors.affiliation: Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hashimoto
authors.affiliation: Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan; Laboratory for Motor Learning Control, RIKEN Brain Science Institute, Wako, Saitama, Japan; Japan Society for the Promotion of Science Research Fellow, Chiyoda, Tokyo, Japan.
authors.forename: Takeru
authors.initials: T
authors.lastname: Honda
authors.affiliation: Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Matsumura
authors.affiliation: Laboratory for Motor Learning Control, RIKEN Brain Science Institute, Wako, Saitama, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakao
authors.affiliation: Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan.
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Soga
authors.affiliation: KATANO TOOL SOFTWARE, Ichikawa, Chiba, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Katano
authors.affiliation: Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Yokota
authors.affiliation: Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Mizusawa
authors.affiliation: Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan; Laboratory for Motor Learning Control, RIKEN Brain Science Institute, Wako, Saitama, Japan; Nozomi Higher Brain Function Laboratory, Nozomi Hospital, Ina-machi, Kita-adachi-gun, Saitama, Japan.
authors.forename: Soichi
authors.initials: S
authors.lastname: Nagao
authors.affiliation: Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan.
authors.forename: Kinya
authors.initials: K
authors.lastname: Ishikawa
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D016022:Case-Control Studies; D002524:Cerebellar Ataxia / Q000503:physiopathology*; D002531:Cerebellum / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D046709:Pattern Recognition, Physiological / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*