Investigating the consistency of brain activation using individual trial analysis of high-resolution fMRI in the human primary visual cortex |
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Authors: | Ajay K. Nemani Ian C. Atkinson Keith R. Thulborn |
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Affiliation: | aCenter for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, IL 60612, USA;bDepartment of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA;cDepartment of Radiology, University of Illinois at Chicago, Chicago, IL 60612, USA;dDepartment of Electrical and Computer Engineering, University of Illinois at Chicago, Chicago, IL 60612, USA |
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Abstract: | Conventional functional magnetic resonance imaging using blood oxygenation level dependent contrast requires signal averaging and statistical methods to detect activation. Signal averaging implicitly assumes that brain activation in response to a stimulus is reproducible on the scale of the imaging voxel. This assumption is examined in the absence of averaging by analyzing individual trials of individual voxels that approach the size of the functional unit, the cortical column, in the human primary visual cortex. In the absence of spatial and temporal averaging, even highly active voxels demonstrate inconsistent activation to the same repeated stimulus despite consistent behavioral responses. This observation implies a variable selection of suitable cortical columns from a population of available functional units to produce consistent perception of the stimulus. The implication of this observation for neuroplasticity and behavioral consistency at the level of functional units is discussed. |
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Keywords: | fMRI BOLD Individual trial Brain function Visual cortex |
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