State-Dependent, Widespread Correlation of Neural and FMRI Endogenous Fluctuations in the Awake Monkey

¹UCNI, LN, NIMH, NIH, Bethesda, MD, USA; ²Institute of Cognitive Neuroscience, University College London, London, UK; ³Neurophysiology Imaging Facility, NIMH,NINDS,NEI,NIH, Bethesda, MD, USA; ⁴Advanced MRI Section, NINDS, NIH, Bethesda, MD, USA

Endogenous fluctuations in the brain were evaluated by simultaneously measuring electrophysiological and fMRI signals in the awake monkey. Fluctuations of the gamma local field potential power and fMRI signals were strongly correlated, not just in the region of the electrode but across a large portion of the cerebral cortex, an effect that was strengthened when the monkeys eyes were closed. These findings demonstrate that a significant portion of the variance in resting state activity is correlated with underlying neural activity, and that the relationship between fMRI and neural signals varies as a function of behavioral state.