Linking the negative BOLD response to decreases in neuronal activity in monkey V1

Previously we demonstrated that the negative BOLD response (NBR) in non-stimulated regions of V1 is associated with decreases in neuronal activity (DsiNA), and that the DsiNA cannot be caused by hypoxia due to the associated negative cerebral blood flow (CBF) response. DsiNA were observed 11 mm away from the stimulated region; thus they cannot be exclusively mediated by the horizontal connections. Aims 1) Are the NBR and DsiNA independent or coupled phenomena? 2) Does the NBR reflect decreases in synaptic or in spiking activity? Monkeys were stimulated visually with rotating checkers. Electrical recordings were obtained simultaneously with fMRI. Peripheral visual-field (VF) stimuli elicited PosBR/NBR in peripheral/more central VF representations in V1. The amplitude of the NBR measured across single trials was correlated with the corresponding amplitude of the DsiNA within single sessions (p