Figure 1.

Study design and cognitive task. (a) Measurements were initiated with a structural T1-weighted image (grey, 8 mins) and ASL at rest (green, 6 mins). Thereafter, fPET was acquired (blue, 52 mins) and an adapted version of the video game Tetris® was played four times with varying cognitive load (6 mins, 2 easy, 2 hard, pseudo-randomized order) separated by resting periods. Simultaneously, ASL was acquired during one easy and one hard condition (green). BOLD data for functional connectivity was acquired during the second easy and hard task blocks, but these were not used in the current study. Immediately after fPET and ASL, BOLD data was acquired with the same task and an additional control condition (red, 12 task blocks, 30 s each, 10 s rest). (b) The task consisted of the conditions easy, hard and control, whereas the latter was only carried out during BOLD imaging. Easy and hard conditions differed by the speed of the falling bricks and the initial number of incomplete lines. In the control condition bricks had to be guided through a chimney and were automatically removed at the bottom. This figure was adapted from Hahn et al. (2020) under CC-BY license.¹⁶