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Cereb Cortex. 2009 Feb;19(2):349-66. doi: 10.1093/cercor/bhn086. Epub 2008 Jun 4.

Area 3a neuron response to skin nociceptor afferent drive.

Author information

1
Department of Biomedical Engineering, University of North Carolina, School of Medicine, Chapel Hill, NC 27599-7545, USA. bwhitsel@med.unc.edu

Abstract

Area 3a neurons are identified that respond weakly or not at all to skin contact with a 25-38 degrees C probe, but vigorously to skin contact with the probe at > or =49 degrees C. Maximal rate of spike firing associated with 1- to 7-s contact at > or =49 degrees C occurs 1-2 s after probe removal from the skin. The activity evoked by 5-s contact with the probe at 51 degrees C remains above-background for approximately 20 s after probe retraction. After 1-s contact at 55-56 degrees C activity remains above-background for approximately 4 s. Magnitude of spike firing associated with 5-s contact increases linearly as probe temperature is increased from 49-51 degrees C. Intradermal capsaicin injection elicits a larger (approximately 2.5x) and longer-lasting (100x) increase in area 3a neuron firing rate than 5-s contact at 51 degrees C. Area 3a neurons exhibit enhanced or novel responsivity to 25-38 degrees C contact for a prolonged time after intradermal injection of capsaicin or alpha, beta methylene adenosine triphosphate. Their 1) delayed and persisting increase in spike firing in response to contact at > or =49 degrees C, 2) vigorous and prolonged response to intradermal capsaicin, and 3) enhanced and frequently novel response to 25-38 degrees C contact following intradermal algogen injection or noxious skin heating suggest that the area 3a neurons identified in this study contribute to second pain and mechanical hyperalgesia/allodynia.

PMID:
18534992
PMCID:
PMC2638786
DOI:
10.1093/cercor/bhn086
[Indexed for MEDLINE]
Free PMC Article
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