The effect of Parkinson's disease on interference control during action selection

Abstract

Basal ganglia structures comprise a portion of the neural circuitry that is hypothesized to coordinate the selection and suppression of competing responses. Parkinson’s disease (PD) may produce a dysfunction in these structures that alters this capacity, making it difficult for patients with PD to suppress interference arising from the automatic activation of salient or overlearned responses. Empirical observations thus far have confirmed this assumption in some studies, but not in others, due presumably to considerable inter-individual variability among PD patients. In an attempt to help resolve this controversy, we measured the performance of 50 PD patients and 25 healthy controls on an arrow version of the Eriksen flanker task in which participants were required to select a response based on the direction of a target arrow that was flanked by arrows pointing in the same (congruent) or opposite (incongruent) direction. Consistent with previous findings, reaction time (RT) increased with incongruent flankers compared to congruent or neutral flankers, and this cost of incongruence was greater among PD patients. Two novel findings are reported. First, distributional analyses, guided by dual-process models of conflict effects and the activation-suppression hypothesis, revealed that PD patients are less efficient at suppressing the activation of conflicting responses, even when matched to healthy controls on RT in a neutral condition. Second, this reduced efficiency was apparent in half of the PD patients, whereas the remaining patients were as efficient as healthy controls. These findings suggest that although poor suppression of conflicting responses is an important feature of PD, it is not evident in all medicated patients.

Reaction time distribution analysis of spatial correspondence effects

“…That the results for variants of the spatial Simon task are reliable and likely representative of the temporal properties of response activation implies that the same should be true for other tasks in which irrelevant stimulus information produces response competition (e.g., Roelofs, 2008;Steinhauser & Hübner, 2009;Wylie et al, 2009). Systematic comparisons of RT distributions across tasks should reveal the factors that influence the time course of response activation and the generalizability of those factors.…”

“…We focus on variants of the spatial Simon task and examine the primary empirical results, determining what conclusions can be reached on the basis of existing studies. The assessment of RT distribution analyses we provide should be of value not only to researchers studying the Simon effect, but also to those investigating a range of correspondence effects to which distribution analyses are applicable (e.g., picture-word categorization, Roelofs, 2008; Stroop interference tasks, Steinhauser & Hübner, 2009; flanker tasks, Wylie et al, 2009).…”

Disentangling the Role of Cortico-Basal Ganglia Loops in Top–Down and Bottom–Up Visual Attention: An Investigation of Attention Deficits in Parkinson Disease

“…If so, one should expect that a BG dysfunction may determine impairments in the ability to suppress conflicting responses, leading to exacerbated interference effects (Wylie, Ridderinkhof, Bashore, & van den Wildenberg, 2010;Wylie et al, 2009;Praamstra, Stegeman, Cools, & Horstink, 1998). In the realm of visual attention, a similar deficit could materialize in the form of a deficit of top-down control, which could be less effectively engaged to counteract the interference effect engendered by a distracting stimulus acting through bottom-up mechanisms.…”

Phase I/II randomized trial of aerobic exercise in Parkinson disease in a community setting

“…We did not have flanker task results in controls, but the level of interference in our patients with PD appeared to be above that observed in healthy elderly, 3 consistent with prior reports in PD. 30 Tolerability and safety. The randomized segment.…”