Daniil P. Aksenov1,2, Limin Li1,2, Gheorghe Iordanescu1,2, Xiaomu Song1,2, Alice Wyrwicz1,2
1Center for Basic MR Research, NorthShore University HealthSystem, Evanston, IL, USA; 2Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
Many questions remain about the relationship between the local cellular metabolic and hemodynamic changes measured by fMRI and the underlying neuronal electrical activity. In this study we examined the effect of neuromediators on BOLD and neuronal activity. Simultaneous fMRI and electrophysiological measurements of whisker stimulation were performed before and after localized injection of the GABA agonist muscimol into the somatosensory cortex. The drug injection affected both neuronal activity and BOLD signal. However, surprisingly, the large reduction in single-unit activity produced by muscimol was accompanied by a relatively small change in BOLD response in the whisker barrel cortex.