In these images, the thalamus is outlined in red on both functional PET (color) and structural MRI (grey) images. Note that activity is different between the left and right halves of the thalamus. Panel A displays the distribution of this asymmetry over the thalamus of one subject.  Panels B-D show this pattern in other individuals. Parodoxically, activity is lowest in the side of the thalamus that receives input from the side of body encompassing the painful region. Despite this sharp contrast with acute pain-induced activation of the thalamus, this relatively low activity may represent long term changes in nerve cells that contribute to the chronic pain syndrome.

For further information see:
Iadarola, M.J, Max,M.B., Berman,K.F., Byas-Smith, M.G., Coghill,R.C., Gracely, R.H,Bennett, G.J. Unilateral decrease in thalamic activity observed with positron emission tomography in patients with chronic neuropathic pain. Pain 63:55-64, 1995.

We welcome any questions. For additional information, reprints, or permission to publish any of these images please contact
Dr. Robert Coghill
Department of Neurobiology and Anatomy
Wake Forest University School of Medicine
Winston-Salem, NC, 27157-1010
rcoghill@wfubmc, phone: (336) 716-4284, fax: (336) 716-4534