Primary afferent input to and receptive field properties of cells in rat lumbar area X
✍ Scribed by Patrick D. Wall; Bradley J. Kerr; Matt S. Ramer
- Book ID
- 102807548
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 855 KB
- Volume
- 449
- Category
- Article
- ISSN
- 0021-9967
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✦ Synopsis
Abstract
In this study we examined the primary afferent input to rat area X of Rexed, and characterized sensory receptive fields (RFs) of the cells therein. This poorly understood area contains primary afferent fibres, some of which are arranged into a compact bundle beneath the central canal. Anterograde transport of the B fragment of cholera toxin (CTB) from the sciatic nerve showed a strictly ipsilateral projection to segments in L4 and L5 but both ipsi‐ and contralateral projections in L6 and more caudal segments. The response of cells in area X to mechanical cutaneous stimuli was recorded through extracellular microelectrodes in decerebrate, decerebrate‐spinal, and urethane‐anaesthetised preparations. The lateral edge of area X was marked by an abrupt change in the RFs: Lateral to area X in the dorsal horn, they were strictly unilateral and relatively small. At a mean of 90 μm from the midline, there was an abrupt expansion of the RFs to cover at least the entire ipsilateral dermatome. Within area X, 70% of the cells' RFs extended across the midline to include contralateral skin. In 35% of cells recorded in rats with intact spinal cords, the RF extended rostrally onto the forelimb. In a small number of cells, the RF included ear pinnae and nose. The precise function of area X cells remains unknown; although they have been shown to be involved in visceral reflexes, the fact that they receive convergent input from a wide variety of tissues and from local and remote body parts implies a more generalized, integrative function. J. Comp. Neurol. 449:298–306, 2002. © 2002 Wiley‐Liss, Inc.