Effects of stimulus-response compatibility in Parkinson’s disease: a psychophysiological analysis

Abstract

The present study investigated the mechanisms underlying stimulus-response compatibility effects in Parkinson's disease patients and matched controls. Since basal ganglia are involved in the selection and inhibition of competing responses we examined whether basal ganglia dysfunction in Parkinson's disease leads to greater interference effects compared to the control subjects. Reaction times and lateralized movement-related cortical potentials (lateralized readiness potential: LRP) were recorded in two modified Eriksen flanker tasks. Both groups were influenced by compatibility conditions; interference was seen as enhanced reaction time and error rate, as well as incorrect early LRP and delayed late LRP in incongruent trials. Altogether, behavioral and electrophysiological measures showed the interference to be rather smaller for the patients than for the controls. In contrast, facilitation did not differ among groups. Hence the claim that Parkinson's disease patients are more influenced than controls by interfering directional stimuli appears not always valid.

Variations in theTNF-α Gene (TNF-α -308G→A) Affect Attention and Action Selection Mechanisms in a Dissociated Fashion

“…The increased attentional processing affects subsequent processing stages of action selection. Data from the e-LRP, reflecting automatic response activation (Falkenstein et al 2006), show a stronger activation of the incorrect response hand on flanker presentation of the AA/AG genotype group. Hence the existence of an A allele seems to adversely affect action selection as driven by the flankers.…”

“…The stimulus-locked (s-LRP) waveforms in incongruent, conflicting trials in a Flanker task usually show an early activation of the incorrect response hand ("dip") (Beste et al 2008a). This dip precedes the negative deflection that reflects the correct response activation may be strongly driven by stimulus processing (Falkenstein et al 2006). TNF-␣ exerts neuroprotective effects in occipital brain structures.…”

“…Due to these neuroprotective effects, we hypothesize that attentional processes are improved in A allele carriers leading to an increased N1 because the N1 is likely generated in these brain areas (Gomez Gonzalez et al 1994;Herrmann and Knight 2001). We further hypothesize that the dip of the e-LRP is also increased as a consequence of the stronger N1 (e.g., Falkenstein et al 2006). On a behavioral level, we hypothesize that especially the e-LRP effect is reflected in increased compatibility effects in RTs in the A allele group, which is paralleled by a delay in the P3b.…”

Deep Brain Stimulation of the Subthalamic Nucleus, but not Dopaminergic Medication, Improves Proactive Inhibitory Control of Movement Initiation in Parkinson's Disease

“…The third clue was provided by clinical investigations showing that PD patients are generally found to be dysfunctional on measures of response inhibition [21], supporting the view that executive control over responses is compromised in PD [22,23]. However, inconsistent observations are reported regarding the nature of this broad deficit: While some authors found that PD patients have difficulties inhibiting an ongoing reaction [22,24,25], others suggested an enhancement instead of an impairment of inhibitory control [26]. We assume that these inconsistencies are partly due to the fact that current models of inhibitory control of responses, and derived psychophysical methods, are incomplete and unable to evidence important executive mechanisms ignored so far.…”

Effects of aging, Parkinson's disease, and dopaminergic medication on response selection and control

“…In PD, several studies found enhanced interference effects (e.g. Praamstra and Plat, 2001;Praamstra et al, 1998;Wylie et al, 2005), but see Falkenstein et al (2006). However, in these studies patients with a long history of PD were examined, being either under medication or tested after a short time period off-medication.…”