Abstract
BackgroundPostoperative 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.MethodsAged (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.ResultsCognitive 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.ConclusionSplenectomy performed under neuroleptic anaesthesia triggers a cognitive decline that is associated with altered spontaneous neuronal activity in the cortex and hippocampus.
Highlights
Postoperative cognitive dysfunction (POCD) is the impairment of perception, memory, and information processing after surgery [1]
Anaesthesia and surgery induced a temporary impairment in spatial memory
No significant low frequency fluctuation (LFF) synchronization was detected in the right primary somatosensory cortex and right hippocampus on postoperative days 1 and 3 (Figs. 2B & 2C), the functional connectivity pattern was almost normal by day 9 (Fig. 2D)
Summary
Postoperative cognitive dysfunction (POCD) is the impairment of perception, memory, and information processing after surgery [1]. First described over 50 years ago [2], POCD is increasingly recognized [3,4,5,6,7,8,9] as a complication of non-cardiac [10] as well as cardiac surgery [11]. The mechanisms by which anaesthesia and surgery affect cognitive function are unknown, but risk factors for POCD include advanced age, long duration of surgery, and respiratory and infectious complications [12,13]. 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
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