Fig. 1: Two-photon imaging of brain motion relative to the skull.
From: Brain motion is driven by mechanical coupling with the abdomen
a, Rapid changes in the curvature of the fluid-filled lens move the focal point between the brain and the fluorescent microspheres adhered to the surface of the thinned skull. b, Head-fixed mouse on a treadmill. c, Representative x–z image through a typical thinned-skull window. This describes the general environment of the 134 locations used for brain and skull tracking. The GFP-expressing brain (green) and fluorescent microspheres (magenta) on the thinned skull are separated by the subarachnoid space. d, Images of the brain (green) and microspheres (magenta) during a stationary period (left) and locomotion (right). The outer bounding boxes enclose the search area for the template-matching algorithm; the inner bounding boxes represent the target used to track movement. This was done for each of the 316 recorded trials at 134 unique locations in 24 mice. There is a rostro-lateral shift of the brain during locomotion when compared to rest (visible in the displacement of the inner box) while the skull remains in the same position. e, Example of measured brain motion and treadmill velocity. Locomotion events (gray) drive rostro-lateral motion of the brain (green), whereas the skull (magenta) remains stationary.
