title: Theta-frequency phase-locking of single anterior cingulate cortex neurons and synchronization with the medial thalamus are modulated by visceral noxious stimulation in rats.
abstract: The rodent anterior cingulate cortex (ACC) is critical for visceral pain and pain-related aversive response in chronic visceral hypersensitive (VH) state. Long-term potentiation (LTP), induced by theta burst stimulation (TBS) in the medial thalamus (MT)-ACC pathway, is blocked in VH rats. However, the neuronal intrinsic firing characteristics and the MT-ACC connectivity have not been investigated in visceral pain. Using repetitive distension of the colon and rectum (rCRD) as a sensitization paradigm, we have identified that the spontaneous firing rates of ACC neurons and the CRD-stimulated neuronal firings were increased after repetitive visceral noxious stimulation. This correlates with increases in visceral pain responses (visceromotor responses, VMRs). Two multichannel arrays of electrodes were implanted in the MT and ACC. Recordings were performed in free-moving rats before and after repeated CRD treatment. Power spectral density analysis showed that the local field potential (LFP) recorded in the ACC displayed increases in theta band power (4-10 Hz) that were modulated by rCRD. Neural spike activity in the ACC becomes synchronized with ongoing theta oscillations of LFP. Furthermore, cross correlation analysis showed augmented synchronization of thalamo-ACC theta band LFPs, which was consistent with an increase of neuronal communication between the two regions. In conclusion, these results reveal theta oscillations and theta-frequency phase-locking as prominent features of neural activity in the ACC and a candidate neural mechanism underlying acute visceral pain.
authors.affiliation: Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China; Centre for Biosystems, Neuroscience and Nanotechnology, City University of Hong Kong, Hong Kong, China.
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China; Centre for Biosystems, Neuroscience and Nanotechnology, City University of Hong Kong, Hong Kong, China.
authors.forename: B
authors.initials: B
authors.lastname: Cao
authors.affiliation: Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China; Centre for Biosystems, Neuroscience and Nanotechnology, City University of Hong Kong, Hong Kong, China.
authors.forename: T R
authors.initials: TR
authors.lastname: Yu
authors.affiliation: Centre for Biosystems, Neuroscience and Nanotechnology, City University of Hong Kong, Hong Kong, China; Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China.
authors.forename: B
authors.initials: B
authors.lastname: Jelfs
authors.affiliation: Centre for Biosystems, Neuroscience and Nanotechnology, City University of Hong Kong, Hong Kong, China.
authors.forename: J
authors.initials: J
authors.lastname: Yan
authors.affiliation: Centre for Biosystems, Neuroscience and Nanotechnology, City University of Hong Kong, Hong Kong, China; Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China.
authors.forename: R H M
authors.initials: RH
authors.lastname: Chan
authors.affiliation: Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China; Centre for Biosystems, Neuroscience and Nanotechnology, City University of Hong Kong, Hong Kong, China. Electronic address: yingli@cityu.edu.hk.
authors.forename: Y
authors.initials: Y
authors.lastname: Li
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001683:Biological Clocks / Q000502:physiology; D003106:Colon / Q000294:innervation; D004195:Disease Models, Animal; D004558:Electric Stimulation; D006179:Gyrus Cinguli / Q000473:pathology*; D008297:Male; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D025341:Principal Component Analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013788:Thalamus / Q000503:physiopathology*; D013826:Theta Rhythm / Q000502:physiology*; D013997:Time Factors; D059265:Visceral Pain / Q000473:pathology*
keywords: anterior cingulate cortex; phase-locking; thalamocortical synchronization; theta oscillation; visceral pain