Tactile Sensory and Pain Networks in the Human Spinal Cord and Brain Stem Mapped by Means of Functional MR Imaging

American Journal of Neuroradiology
DOI 10.3174/ajnr.A1909
N.F. Ghazni, C.M. Cahill and P.W. Stroman

(From the Centre for Neuroscience Studies (N.F.G., C.M.C., P.W.S.), Departments of Pharmacology and Toxicology and Anesthesiology (C.M.C.), and Departments of Diagnostic Radiology and Physics (P.W.S.), Queen's University, Kingston, Ontario, Canada.
Please address correspondence to Patrick W. Stroman, Ph.D., Departments of Diagnostic Radiology and Physics, c/o Centre for Neuroscience Studies, 228 Botterell Hall, Queen's University, Kingston, ON, K7L 3N6, Canada; e-mail: stromanp@queensu.ca)


BACKGROUND AND PURPOSE: Touch and brush sensory stimuli elicit activity in discriminative touch pathways involving specific regions in the spinal cord and brain stem. However, no study has mapped normal sensory activity noninvasively in healthy humans. The purpose of this study is to map the neuronal activity of sensory input to understand abnormal sensory transmission.

MATERIALS AND METHODS: In the present study, spinal fMRI (by using SEEP) was used to map the activity involved with light touch (2 g and 15 g von Frey filaments) and brush stimuli in the brain stem and spinal cords of 8 healthy volunteers. The results were spatially normalized and analyzed with custom-made software. Areas of SEEP activity were identified by using general linear model analysis.

RESULTS: The 2 g von Frey filament showed predominant activity in the medulla around the ipsilateral dorsal gracile and cuneate nuclei. The 15 g filament elicited significant activity in the ipsilateral dorsal and contralateral ventral gray matter areas of the spinal cord, areas around the olivary nuclei, pontine reticular formation, periaqueductal gray, and raphe nuclei in the rostral pons and midbrain. The brush stimuli elicited more activity in the medulla around the ipsilateral cuneate and gracile nuclei.

CONCLUSIONS: The 2 g filament and brush stimuli activated areas associated with a touch response. The 15 g filament activated areas associated with a pain response. The results from this study identify specific neuronal regions in the brain stem and spinal cord involved in sensory transmission and help understand altered sensory and pain states.


Abbreviations: vGM, ventral gray matter, BOLD: Blood Oxygen Level-Dependant, dGM: dorsal grey matter, SEEP: signal intensity enhancment by extravascular protons

Full article (open access): http://www.ajnr.org/cgi/reprint/ajnr.A1909v1