Tijdsperceptie en prospectief geheugen bij de ziekte van Parkinson
Summary
Patients with Parkinson’s disease exhibit deficits in perception of time, which are related
to dysfunction of dopaminergic systems in the basal ganglia. A depletion of dopamine in
the basal ganglia is thought to slow down the rate of an ‘internal clock’. According to the
‘scalar timing theory’ this would cause an underestimation of time on a time estimation
task and an overestimation of time on a time production task. For a time reproduction
task this slower rate isn’t supposed to cause an effect. Also in prospective memory timing
processes seem necessary to carry out an action at the right moment. The aim of the
present study was to investigate whether patients with Parkinson’s disease show a pattern
on time perception tasks that fits a lower frequency of the internal clock. The second goal
was to explore whether the assumed slower rate also has an effect on the timing
components which are important in prospective memory. We compared 9 medicated
patients with Parkinson’s disease with 7 healthy control subjects on a time estimation,
production and reproduction task and on a prospective memory task with an event-based
as well as an time-based element. For the reproduction task no group differences were
found. For the estimation and production task a pattern was found that fits a faster rate of
an internal clock, in contrast to the assumed slower rate. A possible explanation for this
pattern is the dopaminergic medication that was used, which might have accelerated the
rate of the internal clock abnormally. For the prospective memory task no group
differences were found, which might be a result of the complexity of the task and the
small group size.