Dinlenme ile zihinsel stres sırasında kafeinin fMRG dinamiklerine katkısı

Caffeine is an adenosine receptor antagonist with known effects on arousal and cerebrovascular tone. Yet its rapid, systemic impact on fMRI signals and their cou pling to physiology remains understudied. We examined how caffeine modulates BOLD responses and systemic physiology across two intake delays (10 vs. 30 minutes; Caff 10, Caff-30), and two different scanning conditions, arithmetic equation solving and resting-state. GLM analysis revealed robust activation in task-positive networks. Es pecially, the IPS, one of the active regions, is crucial in number processing. Relative to Caff-10, Caff-30 showed modestly greater activation in IPS and insula, alongside pat terns near sulcal territories, suggesting a vascular contribution on task responses. Also, we conducted ICA, dual regression, and voxel-wise cross-correlations between BOLD RVT, and BOLD-PPG-Amp. Resting-state ICA prioritized a WM/ventricular pattern, whereas the analogous component emerged later during task, implying stronger vari ance attributable to systemic processes at rest. Dual regression did not yield signif icant results, which is reflecting limited power and network overlap. However, cross correlation analyses draw a consistent picture. Caffeine lengthened and broadened physiology-BOLD coupling. In rest, Caff-30 exhibited earlier negative and prolonged positive RVT-BOLD correlations. For PPG-Amp, spatial expression shifted by caffeine from more localized VIS effects (Caff-10) to widespread WM-CSF patterns (Caff-30). Together, these results indicate that on the timescale of minutes, caffeine reshapes both the temporal and spatial dimensions of systemic influences on BOLD, while modestly enhancing task-relevant activations. Recent caffeine intake can affect physiological vari ance and alter network engagement. Therefore, researchers must measure and control physiological signals when interpreting fMRI results.