Separating Storage from Retrieval Dysfunction of Temporal Memory in Parkinson's Disease

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Abstract
Dysfunction of the basal ganglia and the brain nuclei interconnected with them leads to disturbances of movement and cognition exemplified in Parkinson's disease (PD) and Huntington's disease, including disordered timing of movements and impaired time estimation. Previous research has shown that whereas striatal damage in animals can result in the loss of temporal control over behavior, dopaminergic deregulation in the human striatum associated with PD distorts the memory for time. Here we show a dissociation between deficits in storage (writing to) and retrieval (reading from) temporal memory processes. Both are dysfunctional in PD and sensitive to treatment with dopaminergic agents, but produce dissimilar distortions. When time intervals are stored in memory while the subjects are dopamine depleted, the process is slowed, leading to overestimation of two different time intervals. Conversely, when retrieval occurs in a dopamine-depleted state, interference or coupling occurs between two remembered time intervals, producing overestimation of the shorter and underestimation of the longer one. Whether those two separable patterns of dysfunction in storing and retrieving temporal memories rely on distinct neural networks within the basal ganglia and/or their cortical targets remains to be answered by future research.