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This Article Full Text Full Text (PDF) All Versions of this Article: 586/6/1529    most recent jphysiol.2007.145672v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bremner, L. R. Articles by Fitzgerald, M. Search for Related Content PubMed PubMed Citation Articles by Bremner, L. R. Articles by Fitzgerald, M. Related Collections Neuroscience

¹ Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK

Spinal nociceptive processing undergoes extensive maturation in the postnatal period. The large excitatory cutaneous receptive fields and sensitivity to mechanical stimulation in the first weeks of life suggest a lack of inhibitory control in developing spinal sensory pathways, which cannot be easily explained at the synaptic level. We hypothesized that developmental changes in dorsal horn inhibition occur at the network level, and tested this by mapping the spatial and modality organization of dorsal horn cell inhibitory receptive fields (RFs) in decerebrate spinal adult and neonatal rats. We report two novel results. First, although contralateral inhibition of dorsal horn cells was well established by postnatal day 3 (P3), inhibitory RFs were significantly less spatially restricted at P3 than in the adult and the intensity of inhibition across the RF was more evenly distributed in the neonate. Second, contralateral inhibitory RFs could be activated by both low- and high-intensity stimulation in the neonate, in contrast to the situation in adult where high-intensity pinch is normally required. These results demonstrate substantial postnatal changes in the organization or ‘tuning’ of inhibition in the developing dorsal horn, which are likely to contribute to the maturation of tactile and nociceptive spinal processing and coordinated sensorimotor and pain behaviour.

(Received 27 September 2007; accepted after revision 6 December 2007; first published online 13 December 2007)
Corresponding author L. R. Bremner: Division of Biology, California Institute of Technology, Pasadena, California 91125, USA. Email: lindsay{at}vis.caltech.edu