fMRI and neuronal activity in awake behaving macaques

Massachusetts General Hospital, Boston MA

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Abstract

DESCRIPTION (provided by applicant): Recently there has been an enormous increase in knowledge about the human brain, based on functional magnetic resonance imaging (fMRI) and related techniques. Unfortunately, fMRI does not measure neural activity directly; it only measures the response of adjacent blood vessels to the neural activity of interest. Without additional information it is difficult to interpret the local electrical activity of the neurons themselves. The proposed experiments are designed to fill this knowledge gap by directly comparing neural activity to the fMRI results, in awake behaving macaque monkeys. We plan three specific aims, in progressively higher-order regions of visual cortex, as a 'bottom-up' approach to understanding the fMRI-neural response relationship at different levels of information processing complexity. First, in primary visual cortex (area V1), we will re-test previous predictions about the neural-fMRI relationship in awake behaving macaques, and compare the extent of electrical and fMRI activity in retinotopic (visual field) coordinates. Secondly we will test the neural-fMRI relationship in MT, a visual area specialized for processing visual motion, using motion adaptation to reveal direction-selective responses. Finally, we will test the neural-fMRI relationship in a higher-order region of visual cortex which appears to be specialized for processing faces and other visual objects.