Fig. 1.

Fiber bundle geometry for light delivery (circles) and detection (squares). In the unmodified regions of the rectangular grid, nearest-neighbor source-detector spacings are 13 mm (S channels), but relocated detectors are placed 6 mm from sources at labeled locations $A$, $B$, and $C$ to provide three VS channels. The circle around location $B$ (radius 25 mm) indicates the zone of target channels considered “near to $B$” in the data analysis; see text for details. N.B.: view from back (convex side) of the near-infrared spectroscopy headpiece. Key: dashed squares—vacated detector gridpoints, shaded squares—selected detectors for S/VS comparison.