Attentional Strategies and Movement Related Potentials in Huntington’s Disease

Katherine Johnson1, 2, Ross Cunnington3, Robert Iansek2,
John Bradshaw1, Nellie Georgiou1, & Ed Chiu4

1. Department of Psychology, Monash University, Clayton, Australia
2. Geriatric Research Unit, Kingston Centre, Cheltenham, Australia
3. Department of Neurology, University of Vienna, Vienna, Austria
4. Huntington’s Disease Clinic, Department of Psychiatry,
University of Melbourne, Carlton, Australia

 

Movement related potentials and movement performance of Parkinson’s disease patients may be significantly improved by using attentional strategies to consciously control movements which would normally be automatically controlled. This experiment was performed to investigate whether the movement performance of Huntington’s disease patients would also benefit from the use of attentional strategies. Movement related potentials reflect increasing cortical activity related to the preparation and execution of voluntary movement. Movement related potentials are maximal over the supplementary motor area; an area of the cortex involved in the planning and preparation of movement parameters. The supplementary motor area receives input from the basal ganglia, which is damaged in both Huntington’s disease and Parkinson’s disease.

Movement related potentials were recorded from eight Huntington’s disease patients, and six controls, whilst they performed an externally-cued sequential button pressing task. In one condition the participants were explicitly instructed to anticipate the presentation of a predictably timed go signal, so that they could internally generate a response and move as quickly as possible, when the cue occurred. In the other condition, the participants were not given any instructions regarding anticipation of the cue. The use of the attentional strategy significantly increased the early slope of the movement related potential for both the Huntington’s disease group and the control group. The control group, for both conditions, always had a significantly steeper early slope than the Huntington’s disease group. The control group was significantly faster than the Huntington’s disease group in how quickly it moved from one button to the next in the sequence. Both groups were significantly faster with the anticipatory strategy than without. By using the attentional strategy, the movements may have been prepared by more conscious motor control processes, which were less likely to be affected by basal ganglia dysfunction. Attentional strategies may be of use in improving movement performance in Huntington’s disease.