Bimanual control differs between force increment and force decrement

Force Variability predicted from cross-correlation coefficient 4 6 8 10 12 14 F o rce V ar iab il it y 0 4 8 12 16 20 24

Force Error predicted from amplitude of coherence in 0.5-1Hz 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 For c e Er ror 0.0 0.1 0.2 0.3 0.4 0.5 0.6

Force Error predicted from cross-correlation coefficient 0.1 0.2 0.3 0.4 For c e Er ror 0.0 0.1 0.2 0.3 0.4 0.5 0.6 For c e Er ror 0.0 0.1 0.2 0.3 0.4 Bimanual Unimanual C ro ss C o rr el at io n C o ef fi ci en t 0.0 0.2 0.4 0.6 0.8 F o rce V ar iab il it y 0 6 8 10 12

Force variability predicted from amplitude of coherence in 0.5-1Hz 2 4 6 8 10 12 14 F o rce V ar iab il it y 0 4 8 12 16 20 24 A m pl it ude of C ohe re nc e 0.0 0.2 0.4 0.6 0.8 1.0

BIMANUAL CONTROL DIFFERS BETWEEN FORCE INCREMENT AND

FORCE DECREMENT

Tasnuva Alam1, Prakruti Patel1, Neha Lodha1

1_{Department of Health and Exercise Science, Colorado State University}

MOTIVATION

METHODS

1N

1s Target total force

6.5s 6.5s

Force tracking task involved gradual force increment and decrement

20% MVC Force increment 3% MVC/s Force decrement 3% MVC/s Participant total force

CONCLUSION

A) Force Error and B) Force variability was greater in force

decrement than increment across both hand conditions. Force phase

Decrement

**

C) Time series cross-correlation was significantly increased during force

decrement than force increment phase. D) Amplitude of coherence between force output of two hands was greater in force decrement than increment phase.

Decrement

Increment

#

Force phase Force phase Force phase

Temporal & frequency based coordination predicted total force accuracy (A&B) & force variability (C&D). Greater temporal correlation and higher coherence in 0.5 to 1 Hz reduced accuracy and increase variability.

Bimanual task performance deteriorates during force decrement compared with force increment. Further, bimanual coordination increases in force decrement than force increment. Most importantly, this study shows that bimanual coordination predicts the accuracy and variability of the total force in dynamic bimanual force control task.

Our findings highlighted that bimanual force control varies with task constraint and importance of collaborative function of two hands to achieve a common task goal. These results may have implications for understanding changes in bimanual control with aging and neurological disorders.

RESULTS

Despite significant proportion of daily activities involving bimanual function, force control strategies involved in bimanual control during precise force increment and decrement are not known.

Purpose

a) To investigate whether task performance and bimanual coordination differs between force increment and decrement.

b) To determine the contribution of bimanual coordination to task performance during force increment and decrement while performing isometric finger flexion.

M

N

&

R

L

Seventeen right-handed healthy young adults

(24.10 ± 3.09 years, 9 females) performed a visually guided force tracking task using

isometric finger flexion in unimanual and bimanual condition. A) B)

C)

Bimanual task performance Bimanual coordination

Predicting Bimanual Task performance from Bimanual Coordination Experimental setup

Force tracking task

Increment Increment Decrement 0-0.5 Hz 0.5-1 Hz Increment Decrement

*

**