Biology subjects

Itaguchi, Y.

Publications and source records attributed to Itaguchi, Y..

3 recordsLinked to original sources

bioRxiv2026

Impaired Motor Awareness of Balance Control is Associated with Postural Instability in Parkinson's Disease

BackgroundBalance instability is a major contributor to disability and falls in people with Parkinsons disease (PwP) and is often insufficiently explained by motor impairment alone. Altered awareness of motor control has been suggested to contribute to sensorimotor dysfunction in PwP, but its relationship with balance performance is poorly understood. ObjectiveTo determine whether awareness of balance control, assessed using a control detection task (CDT), differs between healthy controls (HC) and PwP, and whether CDT performance is associated with balance-related measures. MethodsHealthy older adults (n=20) and PwP (n=22) performed a standing version of the CDT based on center-of-pressure (COP) control, using a force plate. CDT accuracy was used as the primary outcome measure. Static balance during quiet standing was assessed using the COP trajectory length and rectangular area. Dynamic standing balance was assessed using the Index of Postural Stability (IPS). Group differences were examined by independent-samples t-tests. Correlations between CDT accuracy and balance measures were analyzed. ResultsThe PwP group showed significantly lower CDT accuracy. Higher CDT accuracy was associated with better static balance in the HC group and the combined sample, and with higher IPS primarily in the PwP group. ConclusionsMotor awareness during postural tasks is altered in PwP and is associated with balance control. These findings suggest that balance instability in Parkinsons disease may involve altered balance-related action-outcome monitoring in addition to motor dysfunction.

neuroscience↗

bioRxiv2026

Altered Motor Awareness in Parkinson's Disease with Progressive Micrographia

Micrographia, characterized by abnormally small handwriting, is a common motor symptom in Parkinsons disease (PD), and has been classified into consistent micrographia (CM) and progressive micrographia (PM), which may reflect different underlying mechanisms. However, the relative contributions of motor execution and sensorimotor processing to these subtypes remain unclear. In this study, forty-five people with Parkinsons disease (PwP) and twenty age-matched healthy controls (HCs) completed a handwriting task and a control detection task (CDT) assessing the ability to distinguish self-generated from externally generated movements. PwP were classified based on handwriting metrics as showing no micrographia, CM, and/or PM. CDT accuracy was significantly lower in PwP than in HCs (p < 0.01) and was particularly reduced in PwP with PM (p < 0.01). These findings indicate that PM is associated with impaired motor awareness, suggesting altered sensorimotor integration as a characteristic feature of this subtype.

neuroscience↗

bioRxiv2025

Effects of bilateral and unilateral mental practice on actual motor performance and event-related desynchronization

Bilateral hand movement has been reported to enhance actual motor performance and increase motor cortex activation more than unilateral hand movement. This study investigated the interaction effects of bilateral and unilateral mental practice on event-related desynchronization (ERD) amplitude and unilateral motor performance, to explore better clinical rehabilitation for stroke patients with hemiparesis. The task was a ball rotation, where participants circulated two balls on their palm by using their fingers. Seventy-six healthy young adults were randomly assigned to one of three mental practice groups or a control group without mental practice. In the mental practice groups, three subgroups of participants engaged in ball-rotation motor imagery for two blocks in different orders: bilateral hand imagery followed by left hand imagery (BL group), left hand imagery followed by bilateral hand imagery (LB group), and consecutive left hand imagery (LL group). The results showed greater improvement in actual motor performance in the BL group than in the control group, while the performance of the LB and LL groups did not significantly differ from that of the control group. Greater ERD was observed in the BL group than in the LL group in the early sets of the first block. However, ERD amplitude decreased with continued mental practice, and significant correlations between ERD and motor performance were limited. These results suggest that engaging in bilateral mental practice before unilateral mental practice is beneficial in improving unilateral motor performance. Bilateral mental practice following unilateral mental practice may provide neither notable improvements nor detrimental effects on unilateral motor action. Our findings also reveal a mismatch between ERD and motor performance, implying that these two measures are not straightforwardly linked.

neuroscience↗