Normal prism adaptation but reduced after‐effect in basal ganglia disorders using a throwing task

Abstract

Prism adaptation is a form of visuomotor learning in which the visual and motor systems need to be adjusted because a visual perturbation is produced by horizontally displacing prisms. Despite being known for over two centuries, the neuronal substrates of this phenomenon are not yet completely understood. In this article the possible role of the basal ganglia in this kind of learning was analysed through a study of Huntington's and Parkinson's disease patients. A throwing technique requiring the use of open loop feedback was used. The variables analysed were visuomotor performance, adaptation rate and magnitude, and the after-effect. The results clearly showed that both Huntington's and Parkinson's disease groups learned at the same rate as control subjects. In addition, despite having a disturbed visuomotor performance, both experimental groups showed the same adaptation magnitude as the control group. Finally, the after-effect, which is measured after removing the prisms, is reduced in both patients groups. This reduction leads to a disruption in the normal adaptation-after-effect correlation found in normal volunteers. These results suggest that basal ganglia are not involved in this type of open-looped visuomotor learning. The large number of patients studied as well as the similarity of the findings between both populations support this hypothesis. By contrast, there is an impairment in the after-effect on both basal ganglia patient populations. This impairment may be the result of the deterioration of the perceptual recalibration process involved in visuomotor learning.

Podokinetic after-rotation in Parkinson disease

“…Do patients with PD retain the ability to adapt locomotor trajectory in response to PK stimulation as do healthy individuals?-Our results agree with other studies indicating that people with PD retain the ability to modify movements in response to external cues and can adapt motor output in different situations (Stern et al, 1988, Fernandez-Ruiz et al, 2003, Contreras-Vidal et al, 2002, Morris et al, 1994, Zijlstra et al, 1998, Dietz et al, 1995. This is the first study that examines the capability of people with PD to adapt locomotor trajectory in response to stepping on a rotating platform, a task that requires generation of motor patterns for turning during walking.…”

“…For instance, subjects with PD can adapt to prisms that alter visual input (Stern et al, 1988, Fernandez-Ruiz et al, 2003, adapt handwriting size in response to visual feedback that displays gain (Contreras-Vidal et al, 2002) and modify cadence appropriately with changes in walking speed (Morris et al, 1994). These results suggest that people with PD not only retain ability for motor adaptation but also that such adaptive strategies may provide functional benefit.…”

Prism Adaptation and Perceptual Skill Learning Deficits in Early-Stage Parkinson's Disease

“…The reason for these results are not clear in the present study; however, some assumptions can be made: (1) retention deficits in PD [11,29] may explain a part of the extension on days 2 and 3 and (2) PD patients need more time for recalibration until they get used to the task, which may remind us of a freezing phenomenon.…”

“…However, Weiner et al [27] reported that PD patients, but not patients with cerebellar injury, showed normal acquisition of prism adaptation, leading the researchers to suggest that it is the cerebellum and not the basal ganglia that plays a crucial role in prism adaptation. In addition, several studies have suggested normal acquisition of prism adaptation in PD patients [28,29]. These studies measured the magnitude and improvement of distortion with respect to a visual target as variable.…”

Nonlinear attractor dynamics in the fundamental and extended prism adaptation paradigm

“…Two kinds of re-adaption processes occur when the context is changed across adaptation and re-adaptation phases. Context changes may be realized by attaching and detaching weights on the throwing arm [21]. 1 This performance error vanishes during the adaptation process.…”