To characterize multiunit activity during fMRI in unanaesthetized rats, Qingqing Zhang et al. from Nanying Zhang’s lab at Pennsylvania State University chronically implanted NeuroNexus A1x16 MRCM16LP MR-compatible probes to record in visual cortex with differential referencing. They compared electrophysiological recordings under the same conditions as fMRI experiments. Their results highlight that multi-unit activity dynamics, and not gamma-band power, best explains multi-phasic BOLD response to blue laser visual stimulation.