Multiple pathways for noxious information in the human spinal cord.
To investigate the pathways of noxious information in the spinal cord in humans, we recorded cortical potentials following the stimulation of A-delta fibers using a YAG laser applied to two cutaneous points on the back at the C7 and Th10 level, 4cm to the right of the vertebral spinous process. A multiple source analysis showed that four sources were activated; the primary somatosensory cortex (SI), bilateral parasylvian region (Parasylvian), and cingulate cortex. The activity of the cingulate cortex had two components (N2/P2). The mean peak latencies of the activities obtained by C7 and Th10 stimulation were 166.9 and 186.0 ms (SI), 144.3 and 176.8 ms (contralateral Parasylvian), 152.7 and 185.5 ms (ipsilateral Parasylvian), 186.2 and 215.8 ms (N2), and 303.0 and 332.3 ms (P2). Estimated spinal conduction velocities (CVs) of the respective activities were 16.8, 9.3, 8.7, 10.1 and 10.7 m/s. CV of SI was significantly faster than the others (P<0.05). Therefore, our results suggested that noxious signals were conveyed through at least two distinct pathways of the spinal cord probably reaching distinct groups of thalamic nuclei. Further studies are required to clarify the functional significance of these two pathways.
Tsuji
Takeshi
T
Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan RISTEX, Japan Science and Technology Agency, Japan.
Inui
Koji
K
Kojima
Seiji
S
Kakigi
Ryusuke
R
D000328:Adult; D001921:Brain / Q000503:physiopathology; D002574:Cervical Vertebrae; D004569:Electroencephalography; D005071:Evoked Potentials; D006801:Humans; D007834:Lasers; D008297:Male; D009431:Neural Conduction; D009434:Neural Pathways / Q000503:physiopathology; D009619:Nociceptors / Q000503:physiopathology; D010146:Pain / Q000503:physiopathology*; D010812:Physical Stimulation; D011930:Reaction Time; D012867:Skin / Q000294:innervation; D013116:Spinal Cord / Q000503:physiopathology*; D013904:Thoracic Vertebrae; D013997:Time Factors