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This Article Full Text Full Text (PDF) Supplemental Figures All Versions of this Article: 102/4/2253    most recent 00166.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Ji, G. Articles by Neugebauer, V. PubMed PubMed Citation Articles by Ji, G. Articles by Neugebauer, V.

RESEARCH-ARTICLE

Hemispheric Lateralization of Pain Processing by Amygdala Neurons

Department of Neuroscience and Cell Biology, The University of Texas Medical Branch, Galveston, Texas

Submitted 25 February 2009; accepted in final form 21 July 2009

ABSTRACT

Recent biochemical and behavioral data suggest right-hemispheric lateralization of amygdala functions in pain. Our previous electrophysiological studies showed pain-related neuroplasticity in the latero-capsular division of the central nucleus of the amygdala (CeLC) in the right brain hemisphere. Here we determined differences in the processing of pain-related signals in right versus left CeLC neurons. Individual CeLC neurons were recorded extracellularly before and after induction of an arthritis pain state in anesthetized rats. Brief innocuous and noxious test stimuli were applied to peripheral tissues ipsi- and contralateral to the recording site. A monoarthritis was induced in the ipsi- or contralateral knee by intraarticular injections of kaolin and carrageenan. Under normal conditions, CeLC neurons in the left amygdala had smaller receptive fields than those in the right, but the magnitude of background and evoked activity was not significantly different. After arthritis induction, neurons in the right, but not left, CeLC developed increased background activity and evoked responses, irrespective of the location of the arthritis (ipsi- or contralateral to the recording site). A protein kinase A (PKA) inhibitor decreased the activity of right CeLC neurons after arthritis induction but had no effect in the left amygdala. Forskolin, however, increased the activity of left and right CeLC neurons under normal conditions. The results show for the first time laterality of pain-related electrophysiological activity changes in individual amygdala neurons. Whereas both left and right amygdala neurons receive nociceptive inputs and can become sensitized in principle, a yet unknown mechanism prevents PKA activation and pain-related changes in the left amygdala.