title: Simultaneous multisite recordings of neural ensemble responses in the motor cortex of behaving rats to peripheral noxious heat and chemical stimuli.
abstract: Chronic motor cortex (MCx) stimulation (MCS) is an effective approach for patients with chronic, intractable neuropathic pain. However, the underlying neural mechanisms are less known. Combining an in vivo simultaneous multisite recording technique with a video-based behavioral tracker, simultaneous neuronal ensemble activities of the MCx and behavioral responses to noxious heat stimuli applied to bilateral hindpaw pads under naïve and inflammatory pain state were studied in freely behaving rats receiving prior implantation of microwire multielectrode array (2 × 4). Totally, 81 active units were sorted and separated from 40 microwire electrodes pre-implanted in the MCx of 5 rats. Under naïve state, 41% (33/81) units were responsive to contralateral, while 27% (22/81) were responsive to ipsilateral heat stimuli. However, the proportion of heat-responsive units under inflammatory pain state induced by subcutaneous bee venom (BV) injection was significantly increased when compared with saline control (BV vs. saline: 60% vs. 48% for contralateral and 51% vs. 37% for ipsilateral, P < 0.05, n = 81 units) as a consequence of recruitment of some previously heat non-responsive to heat sensitive units. Moreover, under the BV-inflamed condition, the discharge rate of the MCx neurons was significantly increased. The time course of increased spontaneous neuronal ensemble activities (n = 81) was in parallel with that of pain-related behaviors following BV injection. It is concluded that there are pain-related neurons in the MCx that can be functionally changed by peripheral inflammatory pain condition.
authors.affiliation: Institute for Biomedical Sciences of Pain, Capital Medical University, Beijing 100069, PR China.
authors.forename: Chang-Ming
authors.initials: CM
authors.lastname: Wang
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.forename: Dan
authors.initials: D
authors.lastname: Lu
authors.forename: Yun-Fei
authors.initials: YF
authors.lastname: Lu
authors.forename: Xue-Feng
authors.initials: XF
authors.lastname: Chen
authors.forename: Yao-Qing
authors.initials: YQ
authors.lastname: Yu
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.forename: Fu-Kang
authors.initials: FK
authors.lastname: Zhang
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001514:Bee Venoms / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D004567:Electrodes, Implanted; D004594:Electrophysiology / Q000379:methods*; D006358:Hot Temperature / Q000009:adverse effects*; D007249:Inflammation / Q000503:physiopathology; D008297:Male; D009044:Motor Cortex / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology* / Q000523:psychology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011999:Recruitment, Neurophysiological / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
chemical_list: D001514:Bee Venoms