DIFFERENTIATION OF HYPOGLYCEMIA-INDUCED COGNITIVE IMPAIRMENTS - AN ELECTROPHYSIOLOGICAL APPROACH

Effects of hypoglycaemia on distinct cognitive processes were assessed with event-related brain-potential (ERP) measures and reaction times in a hybrid selective-attention/response choice task. One group of sub jects received a euglycaemia-hypoglycaemia-euglycaemia treatment order and a second group a euglycaemia-placebo(euglycaemia)-euglycaemia seq uence of treatments. During hypoglycaemia, ERP measures of selective a ttention (selection negativity), response choice (lateralized readines s potential) and reaction time were delayed compared with baseline per formance. After restoration of euglycaemia, the onset of the selection negativity returned to baseline, whereas the lateralized readiness po tential was still delayed, and error frequencies remained elevated. Th ese results suggest that hypoglycaemia delays both the stimulus select ion and the motor-response selection. They further suggest that the st imulus-selection process recovers quickly after restoration of euglyca emia, but that the response-selection process does not. Slow shifts in cortical potentials with a broad frontal distribution that occurred d uring hypoglycaemia, are discussed in relation to frontal lobe mechani sms involved in the control of subordinate, modality-specific selectio n mechanisms.