Fig. 12.

Volumetric and GM -surface images of the change in absorption coefficient at 735 nm (${\lambda }_1$) and 850 nm (${\lambda }_2$) displayed for (a), (b) the left and (c), (d) the right hemisphere activations. Images are an average of a time window of between 190- and 210-s post-activation onset, and reconstructed relative to the mean of the 20-s pre-activation. Each image is thresholded at 50% of the maximum absolute signal deviation found in the volume. The sub-panels in each row show the volume images in (i) sagittal section, (ii) transverse section, and (iii) coronal section, and (iv) an extraction of the GM surface.