Spinal NMDA-receptor dependent amplification of nociceptive transmission to rat primary somatosensory cortex (SI).

Research output: Contribution to journalArticle


The role of NMDA mechanisms in spinal pathways mediating acute nociceptive input to the somatosensory cortex is not clear. In this study, the effect of NMDA-antagonists on nociceptive C fibre transmission to the primary somatosensory cortex (SI) was investigated. Cortical field potentials evoked by CO2-laser stimulation of the skin were recorded in the halothane/nitrous oxide anaesthetized rat.

The SI nociceptive evoked potential (EP) amplitudes were dependent on the frequency of noxious heat stimulation. The amplitudes of SI potentials evoked by CO2-laser pulses (duration 15–20 ms, stimulation energy 21–28 mJ/mm2) delivered at a frequency of 0.1 Hz were approximately 40% of the amplitudes of potentials evoked by 1.0 Hz stimulation.

After intrathecal lumbar application of either of the NMDA-antagonists CPP or MK-801, the amplitudes of nociceptive SI potentials, evoked by 1.0 Hz stimulation of the contralateral hindpaw, were reduced to approximately 40% of controls. By contrast, field potentials evoked by 0.1 Hz stimulation of the hindpaw were unaffected by MK-801.

SI potentials evoked by 1.0 Hz stimulation of the contralateral forepaw did not change after lumbar application of CPP or MK-801, indicating that the depression of hindpaw EPs was due to a segmental effect in the spinal cord.

It is concluded that spinal NMDA-receptor mechanisms amplify the acute transmission of nociceptive C fiber input to SI in a frequency-dependent way.


Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Neurosciences


  • C fibre, Nociception, Pain, Somatosensory cortex, NMDA-receptor, Wind-up
Original languageEnglish
Pages (from-to)195-200
Issue number1-2
Publication statusPublished - 2003
Publication categoryResearch

Related research output

Marcus Granmo, 2008, Unit for Neurophysiology, Neuronano Research Center, Dept. of Experimental Medical Science. 74 p.

Research output: ThesisDoctoral Thesis (compilation)

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