Controlled guidance of handwriting in Parkinson's Disease patients. Can a sonic aid improve tau guidance measures

Abstract

Aim: To identify, using “tau theory” (Lee, 1998), i) if there are significant differences in tau guidance of handwriting between PD patients and normal healthy controls, and if so, ii) whether tau guidance for these actions can be improved by use of external sound cues attempting to provide missing intrinsic tG information. Method: Four patients with Parkinson’s disease (mean age 69 years) were compared with a healthy control on data recorded by Selspot cameras during handwriting trials. There were three conditions: no whoop (NW), after whoop (AW) and with whoop (WW). With whoop was only applicable to circle trials. Results: Tau analysis revealed significant differences between patients and control in the initial NW trial in terms of percent coupling and coupling constant values (k). For signature and sentence trials, modest results were found when AW comparisons were made to both the control and NW data. However, when results were divided into separate analyses of upwards and downwards movements, improvements were apparent (indexed by percent coupling and k values). This was particularly evident in the initially problematic downward movements. Analyses on circle data reveal that one patient displayed continued improvement throughout the experimental conditions whereas others showed less systematic change. Conclusions: Differences observed AW may be due to provision of a neural substrate onto which actions are coupled. However evidence is not conclusive; the limitations of this study are discussed and possible future applications developed.