Effects of internal clock and memory disorders on duration reproductions and duration productions in patients with Parkinson's disease.

Patients with Parkinson's disease (PD) exhibit deficits in perceptual and motor timing as well as impairments in memory and attentional processes that are related to dysfunction of dopaminergic systems in the basal ganglia. The aim of the present study was to assess the relationships existing between impaired duration judgments and defective memory and attention in PD patients. We compared time performance of medicated PD patients and control subjects on a duration reproduction task that is highly memory-dependent, and on a duration production task that could reveal effects of changes in the speed of internal time-keeping mechanisms.

Time perception depends on accurate clock mechanisms as well as unimpaired attention and memory processes.

We report a series of studies aimed at characterizing the relationships between duration judgments and slowing down of the internal clock, attention and memory deficits. Different groups of participants (elderly people, patients with Parkinson's disease, patients with severe traumatic brain injury, and patients with temporal lobe lesions) performed a duration reproduction task and a duration production task in two conditions: a control counting condition and a concurrent reading condition. Participants were also administered reaction time tasks, tapping tasks, and a battery of attention and memory tests.

Relationships between time estimation, memory, attention, and processing speed in patients with severe traumatic brain injury.

The present experiment was aimed at investigating the effects of memory and attention deficits and of information processing slowing on time estimation in patients with severe traumatic brain injury (TBI). Patients with TBI and normal control subjects reproduced and produced durations (5, 14, 38s) in both a control counting condition and in a concurrent reading condition. They also performed finger-tapping tasks at a free rate and at a 1s rate.