The effects of smoking marijuana on cognition and brain function were asses
sed with PET using (H2O)-O-15. Regional cerebral blood flow (rCBF) was meas
ured in five recreational users before and after smoking a marijuana cigare
tte, as they repeatedly performed an auditory attention task. Blood flow in
creased following smoking in a number of paralimbic brain regions (e.g. orb
ital frontal lobes, insula, temporal poles) and in anterior cingulate and c
erebellum Large reductions in rCBF were observed in temporal lobe regions t
hat are sensitive to auditory attention effects. Brain regions showing incr
eased rCBF may mediate the intoxicating and mood-related effects of smoking
marijuana, whereas reduction of task-related rCBF in temporal lobe cortice
s may account for the impaired cognitive functions associated with acute in
toxication. NeuroReport 11:3835-3841 (C) 2000 Lippincott Williams & Wilkins
.