Figure 1. Diagram of experimental design for acquisition of H215O-PET rCBF and physiological (Portapres) data.
Subjects underwent 12 scans, representing 3 repetitions of 4 task conditions which were pseudorandomized in order within and between subjects: (1) effortful isometric exercise, (2) effortless isometric exercise control task, (3) effortful mental arithmetic (serial subtractions), and (4) effortless mental arithmetic control task (counting).