Abstract
Behavioural studies suggest that elevated blood glucose concentrations accelerate response times in complex tasks (Owens and Benton, 2004, Neuropsychobiology). With the present study we aimed to explore the mechanisms subserving elevated blood glucose effects (7 mmol/litre versus fasting levels of 5 mmol/litre) by studying EEG-derived indices of sensorimotor processing. More specifically, the Eriksen flanker task was used to examine glucose-dependent modulations of the P300, the stimulus lateralized readiness potentials (LRPs), and response-locked LRP, to see whether enhanced blood glucose levels affect stimulus evaluation, response planning, and response selection respectively. 10 participants took part in a within-participant double-blind 2-session experiment where either glucose (25 g) or placebo drinks were administered. Initial data suggests slower reaction times, higher error rates and delayed stimulus-locked LRP onset in incongruent compared to congruent and neutral trials. With placebo administration error rates were increased for the non-dominant hand but not the dominant hand; no effects were found for the EEG parameters. This suggests that hyperglycaemia does not affect senorimotor processing in the flanker task. However, the placebo-related increase in error rates together with the findings of (Donohoe and Benton, 2000) support the proposition that beneficial effects of increased blood glucose levels on cognition might only occur when cognitive demands are high.