Quantitative responses of spinothalamic lamina I neurones to graded mechanical stimulation in the cat

被引:23
作者
Andrew, D [1 ]
Craig, AD [1 ]
机构
[1] Barrow Neurol Inst, Div Neurosurg, Atkinson Pain Res Lab, Phoenix, AZ 85013 USA
来源
JOURNAL OF PHYSIOLOGY-LONDON | 2002年 / 545卷 / 03期
关键词
D O I
10.1113/jphysiol.2002.027342
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
Nociceptive spinothalamic tract (STT) neurones in lamina I of the lumbosacral spinal cord of anaesthetized cats were characterized by recording their responses to graded mechanical stimulation with controlled forces of 10-120 g and probes of 5.0, 0.5 and 0.1 mm(2) contact area. Neurones were identified by antidromic activation from the contralateral thalamus, and cells that responded to noxious stimulation were categorized as either nociceptive specific (NS, n = 20) or as polymodal nociceptive (HPC, responsive to heat, pinch and cold, n = 19) based on their responses to quantitative thermal stimuli. The mean responses of the 39 units increased linearly as stimulus intensity increased, and the population stimulus-response curves evoked by each of the three probes were all significantly different from each other. Thresholds were 45 g for the 5.0 mm(2) probe, 30 g for the 0.5 mm(2) probe and 20 g for the 0.1 mm(2) probe. Further analysis showed that the NS neurones encoded both stimulus intensity and area (probe size) significantly better than HPC neurones in terms of their thresholds to individual probes, their peak discharge rates, their suprathreshold responsiveness and their ability to discriminate the three different probe sizes. These differences are consistent with the known differences between the mechanical encoding properties of A-fibre nociceptors, which provide the dominant inputs to NS neurones, and C-fibre nociceptors, which are the dominant inputs to HPC cells. Comparison of the stimulus-response curves of NS and HPC neurones indicated that the discharge of NS neurones better match the psychophysics of mechanical pain sensations in humans than the discharge of the HPC neurones do. Our findings support the view that NS neurones have a prominent role in mechanical pain and sharpness, and they corroborate the concept that the lamina I STT projection comprises several discrete channels that are integrated in the forebrain to generate qualitatively distinct sensations.
引用
收藏
页码:913 / 931
页数:19
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