Dopaminergic Modulation of Visual-Spatial Working Memory in Parkinson’s Disease

Abstract

Visual-spatial working memory (WM) impairment is frequently associated with the early stage of Parkinson’s disease (PD). The aim of this study was to evaluate the performance of a group of PD patients in visual-spatial and visual-object WM tasks and to investigate the effect of administering the dopaminergic agonist apomorphine (experiment 1) or the dopamine precursor L-dopa (experiment 2) on the performance of tests assessing these functions. To study WM processes, the PD patients and age-matched normal controls were given an n-back task paradigm. In both experiments, the PD patients were submitted to two evaluations: one after a 12-hour therapy washout and the other 15 min after a subcutaneous infusion of apomorphine (average 0.04 mg/kg) or 20/30 min after L-dopa intake (200 mg p.o.). The apomorphine infusion had a worsening effect on reaction times in both visual-spatial and visual-object WM tasks, but it did not influence performance accuracy. Instead, L-dopa administration had a ameliorative effect on accuracy and reaction times in both visual-spatial and visual-object tasks. These results highlight the role of dopamine in the modulation of the WM function in PD patients.

Levodopa/Carbidopa Intestinal Gel for Treatment of Advanced Parkinson’s Disease: An Update on the Effects of Cognitive Functions

“…Thus, DRT would be detrimental on subsets of cognitive functions mediating learning activities based on the integration of environment feedback with ongoing behavior. This dichotomy is somehow consistent with previous observations that DRT improves cognitive functions mediated by the dorsal striatum, such as selective attention, category judgment, time estimation, visual-spatial processing, implicit and explicit retrieval, set shifting and task switching [37] [39] [40] [51] but impairs functions mediated by the ventral striatum such as implicit and explicit learning, impulsivity, reversal learning and orienting to stimuli [52] [53] [54]. These neuropsychological findings parallel the different pathological involvement of the dorsal and ventral striatum in PD.…”

Working memory in Parkinson's disease patients: clinical features and response to levodopa

“…A few studies have reported a beneficial impact of this agent on certain aspects of frontal lobe-related functions 10,11 , including short-term and WM 12,13 . The aims of the present study were to assess the existence of WM deficit in PD, to determine if such deficits are associated with the capacity to maintain information in short-term memory or the nature of the information being processed in WM and to evaluate the effect of dopaminergic therapy over WM.…”

Pharmacological Strategies for Enhancing Cognition in Schizophrenia

“…Although several of these agents are not selective for dopamine, and it is likely that all of these drugs influence neurotransmitter systems other than the dopamine system, such results are generally consistent with the hypothesis that administration of dopamine agonists can improve working memory. Further, there is evidence that levodopa can improve working memory and related cognitive functions in individuals with impaired dopamine function, such as those with Parkinson's disease (Cools et al 2002;Cooper et al 1992;Costa et al 2003;Kulisevsky et al 1996Kulisevsky et al , 2000Lange et al 1995).…”