RETRACTED: Vagus nerve stimulation modulates visceral pain-related affective memory
Authors: Jun Wang
Vivian Oi Vian Tung
Bing Cao
Ying Li
Ni Yan
Xu Zhang
Jin Liu
Journal: Behavioural Brain Research (2013)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: biopsychosocial model; pain perception; visceral pain; conditioned place avoidance; perigenual anterior cingulate cortex
Affiliations: Neuroscience Laboratory, Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong, China., Neuroscience Laboratory, Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong, China. Electronic address: .

Abstract:  Within a biopsychosocial model of pain, pain is seen as a conscious experience modulated by mental, emotional and sensory mechanisms. Recently, using a rodent visceral pain assay that combines the colorectal distension (CRD) model with the conditioned place avoidance (CPA) paradigms, we measured a learned behavior that directly reflects the affective component of visceral pain, and showed that perigenual anterior cingulate cortex (pACC) activation is critical for memory processing involved in long-term visceral affective state and prediction of aversive stimuli by contextual cue. Electrical vagus nerve stimulation (VNS) has become an established therapy for treatment-resistant epilepsy. VNS has also been shown to enhance memory performance in rats and humans. High-intensity VNS (400 μA) immediately following conditional training significantly increases the CRD-induced CPA scores, and enhanced the pain affective memory retention. In contrast, VNS (400 μA) had no effect on CPA induced by non-nociceptive aversive stimulus (U69,593). Low-intensity VNS (40 μA) had no effect on CRD-induced CPA. Electrophysiological recording showed that VNS (400 μA) had no effect on basal and CRD-induced ACC neuronal firing. Further, VNS did not alter CRD-induced visceral pain responses suggesting high intensity VNS facilitates visceral pain aversive memory independent of sensory discriminative aspects of visceral pain processing. The findings that vagus nerve stimulation facilities visceral pain-related affective memory underscore the importance of memory in visceral pain perception, and support the theory that postprandial factors may act on vagal afferents to modulate ongoing nature of visceral pain-induced affective disorder observed in the clinic, such as irritable bowel syndrome. 

Retracted: Yes

PubPeer comments:
 *[below]* Fig. 2:  Visceromotor response (VMR)to graded intensities of CRD in control rats and rats with high-intensity VNS (400 A). (A) Representative abdominal muscle electromyograms (EMG) of the VMR to graded-pressure CRDs (20, 40 and 60 mmHg) recorded from the external oblique pelvic muscle in control rats and rats with high-intensity VNS (400 A) delivered pre- or post-CRD. No obvious difference was found among the three groups. Arrows indicate the time-point of VNS delivery . Here compared with *[above]* Fig 4 from [Cao et al (2012)] .  VMR to graded pressure CRDs in control rats, CCK-8 infusion and 5% peptone infusion rats. (A) Representative abdominal muscle electromyograms of the VMR to graded-pressure CRD (20, 40 and 60 mmHg) recorded from the external oblique pelvic muscle in normal rats and rats with CCK-8 and peptone infusion. No obvious difference was found among the three groups. ![file] Four of the EMGs re-appear, as a result of different conditions. The only difference sems to be the VNS delivery breaks in the 2013 versions. , 
 Retracted [16 March 2020] :  This article has been retracted: please see Elsevier Policy on Article Withdrawal . The corresponding author has requested that the paper be retracted. One figure in the paper (Fig. 2) contained data that were duplicated from a previous publication. More specifically, Fig. 2(A) which shows the visceromotor responses to graded intensities of colorectal distension in control rats and rats with high-intensity vagus nerve stimulation, contain readings of Pre-CRD VNS rats at 20mmHg, Control rats at 40mmHG, and CRD + VNS rats at 60mmHg. These data are duplicates of those in Fig. 4(A) in a previous publication from the same laboratory [Cao et al. (2012), Molecular Brain, 5:19; http: www.molecularbrain.com content 5 1 19]. ,