Figure 1

Experimental design and placement of optodes. (a) The experimental design. After implantation of optode sockets, the animals were trained on the Klüver board task (shown in the image at the right) and the vertical slit task. We first measured hemodynamic responses evoked during the Klüver task with fNIRS before infarction. Focal infarcts were then induced by local injection of endothelin-1 into the posterior limb of the internal capsule. After the recovery of dexterous hand movements with postlesion motor training, the hemodynamic response evoked during a small-object retrieval task (Klüver board or vertical slit) was again measured with fNIRS. A pharmacological inactivation experiment was performed by using muscimol, a gamma-aminobutyric acid receptor agonist. MRI scans were performed to decide on and confirm the arrangement of optode sockets, to decide on the stereotaxic coordinates for the endothelin-1 injection, and to evaluate the size of the infarcts. Finally, the brain damage caused by the infarcts and the locations of the muscimol injections were confirmed histologically in Nissl-stained brain sections. (b) The arrangement of fNIRS optodes on the skull surfaces of the monkeys.