Indeed, when the LC caffeine group was compared with the control group (Figure 1), increases in perfusion occurred bilaterally in the inferior frontal gyrus-anterior insular cortex (predominantly on the right side) and in the uncus, on the left side in the internal parietal cortex, on the right side in the lingual gyrus and cerebellum. In the HC group compared with the control group, perfusion increases were located bilaterally in hypothalamus.
When both caffeine groups were pooled and compared with the whole Inhibitors,research,lifescience,medical control group, significant perfusion increases occurred bilaterally in the inferior frontal gyrus-anterior insula, hypothalamus, right cerebellum, and left uncus (Figure 1). Figure 1 Caffeine-induced perfusion changes superimposed on transaxial slices of a standard MRI surface : left column : Low consumption (LC) group (n=8) vs control group (n=8); middle column : High consumption (HC) group (n=6) vs control group (n=6); right column … Discussion The main findings of this study were the lack of significant differences Inhibitors,research,lifescience,medical in perfusion between
caffeine-exposed subjects and controls, Inhibitors,research,lifescience,medical whether they were HC or LC, the lack of effects of the methylxanthine on the areas of reinforcing and reward and only very discrete changes in perfusion in areas mediating mainly anxiety, attention and vigilance, and cardiovascular function. The vasoconstrictive properties of caffeine in the brain have been known for a long time, and caffeine Inhibitors,research,lifescience,medical has been shown to decrease cerebral blood flow in humans.19-23 Previous studies used the 133Xe-xenon inhalation technique,22 positron emission tomography,19 inversion recovery perfusion MR technique  and blood oxygenation level-dependent (BOLD) signal intensity changes in functional MRI (fMRI).22,23 Recent papers studied the effects of caffeine on cerebral circulation since caffeine ingestion Inhibitors,research,lifescience,medical might be a source of errors in functional brain imaging experiments.20,21,23 The present study showed a 6% to 8% statistically nonsignificant caffeine-induced decrease
in perfusion. Several other studies reported caffeine-induced cerebral blood flow decreases ranging from 3.4% to 18%19,20,22,24,25 but not consistently in all subjects.22 Nature Reviews Molecular Cell Biology The reasons for the discrepancies may have various origins. First, the hemodynamic response measured by different techniques (cerebral blood flow, BOLD contrast, or perfusion changes) is not directly comparable. Second, in most if not all studies, the same dose of caffeine was given to the subjects independently of body weight. Conversely, in the present study, the dose of caffeine ingested was adjusted to body weight, ie, 3 mg/kg. The third factor differing amongst the studies is the period of abstinence from caffeine. The latter was Natural Product Library purchase similar to the one applied here, ie, about 12 h in several studies,19,23 very short, 2 to 3 hours in other studies,22,24 or much longer, ie, 30 hours.