ALCOHOL ACTIVATES THE CEREBRAL REWARD SYSTEM IN MAN

Objective: We investigated the effect of 0.07% alcohol on regional bra in activity at rest and during cognitive performance in order to eluci date the anatomical substrate for the effects of alcohol in man as wel l as to clarify the interaction between changes in cerebral activity i nduced by cognitive performance and alcohol inebriation. Method: Regio nal cerebral blood flow (3D-PET, O-15 Butanol) was measured in 13 male , nonalcoholic volunteers. Each subject was scanned 12 times, three sc ans in each of the following four situations: sober/rest, sober/test a nd inebriated/rest, inebriated/test. We used statistical parametric ma pping and a computerized brain atlas for localization. Results: Alcoho l induced a sense of inebriation and elation as well as a relative inc rease of the cerebral blood flow in medial parts of the temporal lobes , in the antero-basal parts of the anterior cingulate cortex including the septal region. In addition, there was an increase of blood now in midline parts of the lower brain stem. Relative decreases of flow wer e observed in the cerebellum and in the occipital cortex bilaterally. In the sober state, a computerized perceptual maze test and a (silent) serial seven test induced two distinct neocortical activation pattern s that were specific to the tasks. Alcohol did not change these patter ns and the test performance was also uninfluenced. Conclusions: A mode rate dose of alcohol selectively activates target structures that pert ain to the so-called cerebral reward system and the ascending reticula r activating system. Alcohol (approximate to 0.07%) appears to have on ly minor effects in the neocortical systems that are involved in on-li ne cognitive activity. This apparent independence between the subcorti cal alcohol target and the neocortical cognitive mechanisms is a new f inding that appears to be of importance for an understanding of the ef fect of moderate doses of alcohol on the brain.