Article abstract


Nature Neuroscience 9, 569 - 577 (2006)
Published online: 19 March 2006 | doi:10.1038/nn1675

Negative functional MRI response correlates with decreases in neuronal activity in monkey visual area V1

Amir Shmuel1, Mark Augath1, Axel Oeltermann1 & Nikos K Logothetis1


Most functional brain imaging studies use task-induced hemodynamic responses to infer underlying changes in neuronal activity. In addition to increases in cerebral blood flow and blood oxygenation level–dependent (BOLD) signals, sustained negative responses are pervasive in functional imaging. The origin of negative responses and their relationship to neural activity remain poorly understood. Through simultaneous functional magnetic resonance imaging and electrophysiological recording, we demonstrate a negative BOLD response (NBR) beyond the stimulated regions of visual cortex, associated with local decreases in neuronal activity below spontaneous activity, detected 7.15 plusminus 3.14 mm away from the closest positively responding region in V1. Trial-by-trial amplitude fluctuations revealed tight coupling between the NBR and neuronal activity decreases. The NBR was associated with comparable decreases in local field potentials and multiunit activity. Our findings indicate that a significant component of the NBR originates in neuronal activity decreases.

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  1. Max Planck Institute for Biological Cybernetics, Spemannstr. 38, 72076 Tuebingen, Germany.

Correspondence to: Amir Shmuel1 e-mail: Amir.Shmuel@tuebingen.mpg.de

Correspondence to: Nikos K Logothetis1 e-mail: Nikos.Logothetis@tuebingen.mpg.de



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