Elsevier

The Journal of Pain

Volume 2, Issue 4, August 2001, Pages 220-228
The Journal of Pain

Original Reports
Immediate reorganization of the rat somatosensory thalamus after partial ligation of sciatic nerve*,**

https://doi.org/10.1054/jpai.2001.22792Get rights and content
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Abstract

Nerve injury can result in neuropathic pain, which persists after the injury and may occur after healing is completed. The long-term central reorganization associated with neuropathic pain has been previously studied in animal models. The immediate effects of nerve injury on central representation, however, are poorly understood. We examined the population response properties of closely neighboring neurons located in the hindlimb representation area of the somatosensory thalamus. Changes in the neuronal population properties were characterized before, during, and after (up to 6 hours) partial ligation of the sciatic nerve in the rat. Changes in these properties were observed within minutes after nerve injury. There were changes in neuronal class and receptive field size, emergence of new receptive fields, receptive fields observed before ligation disappeared temporarily after ligation, and changes in number of spikes evoked by the same stimulus. The rates of these changes in central representation were essentially zero before ligation, maximal within minutes after ligation, and decreased to a steady sustained rate of change within 1 to 2 hours. The incidence of functional connectivity, as measured by cross-correlations, remained unchanged. However, the strength of functional connectivity increased after ligation. The results show immediate reorganization of lateral thalamic networks with peripheral nerve damage. When the population response is considered as the underlying code, this reorganization does not reflect the behavioral manifestations of hyperalgesia and allodynia, even though some of the individual neuronal responses do reflect properties consistent with the hyperalgesia and allodynia reported within the same time frame after nerve injury in the rat. © 2001 by the American Pain Society

Keywords

Somatosensory thalamus
pain
neuropathic
reorganization
ligation
rat

Cited by (0)

*

Supported by the Department of Neurosurgery at SUNY Upstate Medical University, Syracuse, and NIH Grant WIND5 35115. V. Galhardo was funded by Grant PRAXIS/P/SAU/10170/1998 (Portugal).

**

Address reprint requests to A. Vania Apkarian, PhD, Northwestern University Medical School, Department of Physiology, Tarry Building, 5-703, 330 E Superior St, Chicago, IL 60611. E-mail: [email protected]