Attentional modulation of the R3 component of the blink reflex in parkinson disease

Automatic attention was evaluated in Parkinson's disease (PD) with a psychophysiological method that consisted in analysis of the modulation in the electrically elicited blink reflex R3 potysynaptic component, with and without a fully informative warning prestimulus. We studied 30 parkinsonian patients (stage I-II Hoehn and Yahr; duration of disease <2 years), before and after pharmacological dopaminergic treatment, and 15 normal subjects. The effects of attentional processes on the R3 component were analysed comparing the responses obtained at baseline versus warned condition both in the patient group, before and after treatment, and in controls. Our results showed that attentional modulation was similar to the controls in all patients after treatment, but missing in patients before. This method could thus enable attention evaluation in PD and seems to confirm a direct involvement of dopaminergic pathways in this cognitive function.