Poster E30, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Impact of dopamine depletion on N-40, a marker of the electrophysiological response selection
celine ramdani1, franck vidal2, thierry hasbroucq2; 1french army biomedical research institute, 2Aix-Marseille Université and CNRS
The N-40 is a fronto-central evoked potential, considered as an electrophysiological marker of response selection. Several lines of evidence point supplementary motor areas (SMAs) as a probable generator of the N-40. Indeed, on one side three independent methods, relying on different mathematical principles that the N-40 originates mainly from the medial frontal cortex and very likely from its more superficial part, i.e. SMAs (supplementary motor areas) and on the other side, the N-40 is a marker of the electrophysiological response selection and that response selection seems to take place in SMAs. Considering the existence of basal ganglia-SMAs loops implicated dopamine as a neuromediator, the aim of this study was to evaluate the impact of an acute dopaminergic depletion on the slope of the N-40 to provide a pharmacological argument of the involvement of SMAs in the generation of this evoked potential. The acute dopaminergic depletion was obtained by an acute phenylalanine/tyrosine depletion (APTD); APTD is based on the oral administration of an amino-acid mixture lacking tyrosine and phenylalanine, which selectively lowers dopamine synthesis. The acute dopaminergic depletion decreased the steepness of the slope of the N-40 compared to the placebo session. This result is a pharmacological argument to design SMAs as generator of the N-40. Furthermore, the sensitivity of the N-40 to an acute dopaminergic depletion could be proposed to subjects at a prodromal stage of parkinson disease, before the first symptom. The analysis of this evoked potential could be as an early marker of Parkinson.
Topic Area: EXECUTIVE PROCESSES: Monitoring & inhibitory control