title: Altered functional connectivity in an aged rat model of postoperative cognitive dysfunction: a study using resting-state functional MRI.
abstract: BACKGROUND
  Postoperative cognitive impairment is a common complication after cardiac and major non-cardiac surgery in the elderly, but its causes and mechanisms remain unclear. The purpose of the current study was to use resting-state functional magnetic resonance imaging (fMRI) to explore changes in the functional connectivity, i.e. the synchronization of low frequency fluctuation (LFF), in an animal model of cognitive impairment in aged rats.
  
  
  METHODS
  Aged (22 months) rats were anaesthetized with 40 µg/kg fentanyl and 500 µg/kg droperidol (intraperitoneal) for splenectomy. Cognitive function was assessed using Y maze prior to operation and on postoperative days 1, 3 and 9. To evaluate functional connectivity, resting-state fMRI data were acquired using a 3T MR imaging system with a 4 channel phase array rat head coil.
  
  
  RESULTS
  Cognitive function was impaired at postoperative days 1 and 3 compared with preoperative. Significant synchronized LFF was detected bilaterally in the primary somatosensory cortex and hippocampus preoperatively. By contrast, no significant LFF synchronization was detected in the right primary somatosensory cortex and right hippocampus on postoperative days 1 and 3, although the pattern of functional connectivity had become almost normal by day 9.
  
  
  CONCLUSIONS
  Splenectomy performed under neuroleptic anaesthesia triggers a cognitive decline that is associated with altered spontaneous neuronal activity in the cortex and hippocampus.
authors.affiliation: Department of Anesthesiology, Zunyi Medical College, Zunyi, Guizhou, China, People's Republic.
authors.forename: Peng
authors.initials: P
authors.lastname: Xie
authors.forename: Tian
authors.initials: T
authors.lastname: Yu
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Fu
authors.forename: Ye
authors.initials: Y
authors.lastname: Tu
authors.forename: Yan
authors.initials: Y
authors.lastname: Zou
authors.forename: Su
authors.initials: S
authors.lastname: Lui
authors.forename: Xuna
authors.initials: X
authors.lastname: Zhao
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Huang
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Kemp
authors.forename: Qiyong
authors.initials: Q
authors.lastname: Gong
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D003072:Cognition Disorders / Q000503:physiopathology*; D004195:Disease Models, Animal; D005260:Female; D008279:Magnetic Resonance Imaging; D018782:Maze Learning / Q000502:physiology; D008568:Memory / Q000502:physiology; D009415:Nerve Net / Q000503:physiopathology*; D011184:Postoperative Period; D051381:Rats; D017207:Rats, Sprague-Dawley; D012146:Rest / Q000502:physiology*; D013037:Spatial Behavior / Q000502:physiology