Figure 3.

Composite illustration showing the FD injection site (panels A and B) and terminal labeling in the spinal cord (panel C) in control case SDM84. A: Line drawing of the medial wall of the cerebral hemisphere depicting the location of the FD injection site core (green irregular shape) in the arm/hand representation of M2. The dotted line around the injection site represents the external boundary of the injection site halo. The curved arrow above the injection site indicates that some of the injection site halo was present on the dorsal convexity. The pullout depicts the physiological map of movement representation obtained with intracortical microstimulation used to localize the arm representation of M2 prior to injection of the tract tracer FD. B: A low-power digital photomicrograph of an immunohistochemically processed coronal tissue section through the fluorescein dextran (FD) injection site in the arm/hand region of M2. The dashed line on the injection site represents the external boundary of the injection site core and the dotted line the external boundary of the injection site halo. The blue arrow identifies a coalesced descending labeled fiber bundle emerging from the FD injection site. C: High-power digital photomicrographs of an immunohistochemically processed tissue section through spinal C7 illustrating FD labeled terminal axon fibers and boutons (black arrowheads) in contralateral laminae VII and IX. The blue arrows show fibers in passage. The inset is from the same tissue section but a different microscopic focal plane showing labeled boutons (black arrowheads) in lamina IX. Abbreviations: as, arcuate spur; cgs, cingulate sulcus. For other abbreviations see list. Scale bar = 2 mm in B, 50 μm in C.