title: Corticothalamic modulation on formalin-induced change of VPM thalamic activities.
abstract: Spontaneous activities of single cells were extracellularly recorded in ventral posterior medial (VPM) thalamus of anesthetized rats to characterize the corticothalamic modulation on formalin-induced changes of spontaneous thalamic firing. Formalin injected into the peripheral receptive field, dose-dependently induced the reversible facilitation of spontaneous activities of VPM. However, when the primary somatosensory (SI) cortex was inactivated by muscimol, the pattern of formalin-induced changes of VPM firing was altered. This altered responsiveness included both first and second phase of facilitated spontaneous activities. Bicuculline infused into SI cortex did not alter the pattern of formalin-induced thalamic changes. These results suggest that the pain reactivity of VPM thalamus may be modulated by cortex via corticothalamic pathway during the generation of inflammatory pain.
authors.affiliation: Departments of Dental Pharmacology, College of Dentistry, Kyungpook National University, Daegu, 702-412, Korea.
authors.forename: Sung-Cherl
authors.initials: SC
authors.lastname: Jung
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: In-Sun
authors.initials: IS
authors.lastname: Choi
authors.forename: Jin-Hwa
authors.initials: JH
authors.lastname: Cho
authors.forename: Yong-Chul
authors.initials: YC
authors.lastname: Bae
authors.forename: Maan-Gee
authors.initials: MG
authors.lastname: Lee
authors.forename: Hyung-Cheul
authors.initials: HC
authors.lastname: Shin
authors.forename: Byung-Ju
authors.initials: BJ
authors.lastname: Choi
mesh_terms: D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D005557:Formaldehyde; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009434:Neural Pathways; D009619:Nociceptors / Q000187:drug effects / Q000502:physiology; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000166:cytology* / Q000502:physiology*; D020651:Ventral Thalamic Nuclei / Q000166:cytology* / Q000502:physiology*; D014738:Vibrissae / Q000294:innervation / Q000502:physiology
chemical_list: D018755:GABA Agonists; D018756:GABA Antagonists; D005557:Formaldehyde; D009118:Muscimol; D001640:Bicuculline