Observations on the functional significance of regional cerebral blood flow in “resting” normal subjects

Regional Cerebral Blood Flow (rCBF) of 16 cortical regions was measured bilaterally in 22 healthy adults, with 4–8 repeated measurements per individual. All measurements were done during “rest”, i.e. with minimal external stimulation, by the Xe-133 inhalation method. The data are presented to serve as normal controls for research and clinical work, but more importantly because of their significance for neuropsychological theory. Some rCBF variance is shown to be meaningfully related to handedness, habituation processes, biological rhythms and possibly to regional lateral dominance. Further data and discussion relate to the possible role of frontal lobe structures during non-task-oriented cognition. Finally, data are interpreted as showing that regional functional coupling across the midline, in this situation, is inversely related to the characteristic level-of-processing associated with each area.