Independent components in stimulus-related BOLD signals and estimation of the underlying neural responses.
We measured blood oxygen level dependent (BOLD) responses to the onset of dynamic noise stimulation in defined regions of the primary retinotopic projection (V1) in visual cortex. The response waveforms showed a remarkable diversity across stimulus types, violating the basic assumption of a unitary general linear model of a uniform BOLD response function convolved with each stimulus sequence. We used independent component analysis (ICA) to analyze the component mechanisms contributing to these responses. The underlying neural responses for the components were estimated by nonlinear optimization through the Friston-Buxton hemodynamic model of the BOLD response. Our analysis suggests that one of the identified components reflected a sustained neural response to the stimulus and that another reflected an extremely slow neural response. A third component exhibited nonlinear change-specific transient responses. The first two components showed stable spatial structure in the V1 region of interest with respect to the eccentricity of the noise stimulus.
Tyler
C W
CW
Smith-Kettlewell Eye Research Institute, 2318 Fillmore Street, San Francisco, CA 94115, USA. cwt@ski.org
Kontsevich
L L
LL
Ferree
T C
TC
D000161:Acoustic Stimulation; D000328:Adult; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009622:Noise; D017711:Nonlinear Dynamics; D010100:Oxygen / Q000097:blood; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation / Q000379:methods; D025341:Principal Component Analysis; D013997:Time Factors; D014793:Visual Cortex / Q000098:blood supply* / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology
D010100:Oxygen