The influence of mental and motor load on handwriting movements in Parkinsonian patients (original) (raw)

This experiment tested the hypothesis that ParkinsonÕs disease (PD) patients are more vulnerable to a moderate level of secondary task load than elderly or young controls due to heightened variability in the motor system. PD patients, elderly, and young adults performed a handwriting task with dierent secondary tasks. The secondary task imposed motor load (i.e., speech) and/or a mental load (i.e., ignoring, repeating, or subtracting). The ®ndings showed that, in contrast to young and elderly controls, PD patients tended to increase MT, accumulated pause time, and normalized jerk when the secondary task consisted primarily of motor load. Furthermore, it was shown that PD patients did not reduce writing sizes as result of a high level of mental load which ®nding suggests that writing in an automated fashion does not result in micrographia. The results are discussed in relation to strategies imposed to contend with reduced signal-to-noise levels in the motor system. Ó 1998 Elsevier Science B.V. All rights reserved. 0001-6918/98/$ ± see front matter Ó 1998 Elsevier Science B.V. All rights reserved. PII: S 0 0 0 1 -6 9 1 8 ( 9 8 ) 0 0 0 3 2 -8