| dc.description.abstract | Pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage” can be ignited by noxious chemical (e.g. acid), mechanical (e.g. pressure) and thermal (e.g. heat) stimuli and generated by activation of sensory neurons and their axonal terminals called nociceptors in the periphery. Nociceptive information transmitted from the periphery is projected to the primary somatosensory cortex (S1), secondary somatosensory cortex (S2), insular, anterior cingulate cortex (ACC), amygdala, periaqueductal grey (PAG), and prefrontal cortex (PFC), etc. Local field potential (LFP) attracts an increasing number of attentions as a neurophysiological tool to investigate the combined neuronal activity, ranging from several hundred micrometers to few millimeters (radius) located around the embedded electrode.
In this study, LFPs from the contralateral anterior cingulate cortex (ACC), ventral tegmental area (VTA) and bilateral amygdala, were simultaneously recorded, and differential LFP activities from multiple regions of the brain in response to peripheral noxious stimuli were determined in both anesthetized and freely moving animals. In detail, within the ACC region, LFP powers (intensity) of delta, theta, alpha, beta, and gamma bands increased significantly after formalin injection in both anesthetized animals and freely moving animals. Within the bilateral amygdala regions, LFP powers (intensity) of delta, theta, alpha, and beta bands increased significantly after formalin injection in both anesthetized animals and freely moving animals. However, LFP changes of gamma band could be detected in freely moving animals merely. Within the VTA regions, LFP powers (intensity) of delta, theta, and beta bands increased significantly after formalin injection in both anesthetized animals and freely moving animals. However, LFP changes of gamma band existed only in anesthetized animals. And difference of alpha band was not seen both. Besides, the ACC responded more strongly than that of bilateral amygdala after formalin injection in anesthetized animals only. The results of a Pearson’s r correlation indicated that there was a correlation between behavioral and electrophysiology responses to pain. In detail, these significant relationships were showed in delta band from the ACC and left amygdala; delta, theta, and gamma bands from the right amygdala. | |
