Lesions of DC or STT were performed as previously described37, 38 with slight modifications. Briefly: (1) dorsal column lesions were made bilaterally to a depth of 0.4 mm into the cord using fine tipped Dumont #5 forceps (Fine Science Tools, USA) with aid of a dissecting microscope after a laminectomy at the C3 portion of the spinal cord; (2) For surgical lesions of cuneate nucleus (CN; second-order neurons of DC pathway), the animal was placed in the stereotaxic frame with the head tilted forward, the obex was exposed surgically and the cuneate nucleus was macerated with the fine forceps along its length; (3) For lesioning the STT pathway, the ventrolateral funiculus (VLF) at the C3 portion of the spinal cord was lifted with a fire polished glass rod and the tip of a 22 gauge needle was used to damage the left and right ventrolateral quadrants. Animals in the sham group in each experiment were subjected to a laminectomy or surgical exposure of the obex without damaging the nerve. The rats were allowed to recover for at least 7 days after surgery.