Traumatic stress reactivity promotes excessive alcohol drinking and alters the balance of prefrontal cortex-amygdala activity

Post-traumatic stress disorder (PTSD) and alcoholism are highly comorbid in humans and have partially overlapping symptomatic profiles. The aim of these studies was to examine the effects of traumatic stress (and stress reactivity) on alcohol-related behaviors and neuronal activation patterns. Male Wistar rats were trained to respond for alcohol, were exposed to predator odor (bobcat urine) paired with context and were tested for short- and long-term avoidance of the predator odor-paired context, alcohol self-administration and compulsivity of alcohol responding. Rats were re-exposed to the odor-paired context for western blot analysis of ERK phosphorylation in subregions of the medial prefrontal cortex (mPFC) and the amygdala. Rats that avoided the predator-paired chamber (Avoiders) exhibited persistent avoidance up to 6 weeks post conditioning. Avoiders exhibited increases in operant alcohol responding over weeks, as well as more compulsive-like responding for alcohol adulterated with quinine. Following re-exposure to the predator odor-paired context, Avoiders and Non-Avoiders exhibited unique patterns of neuronal activation in subregions of the mPFC and the amygdala, which were correlated with changes in avoidance and alcohol drinking. Furthermore, activity of upstream regions was differentially predictive of downstream regional activity in the Avoiders versus Non-Avoiders. An animal model for assessing the effect of traumatic stress on alcohol drinking reveals individual differences in neuronal activation patterns associated with re-exposure to traumatic stress-related stimuli, and may provide insight into the neural mechanisms underlying excessive alcohol consumption in humans with PTSD.     

History of Eating Disorder in Mothers of Children with Early Onset Eating Disorder or Disturbance

The literature suggests that there is significant familial aggregation of eating disorders. A specific association has also been reported between childhood feeding problems and maternal eating disorder. This study investigates whether subgroups of children with early onset eating disturbance are distinguished by maternal eating disorder history. The mothers of 66 children with either anorexia nervosa (AN), food avoidance emotional disorder (FAED) or selective eating (SE) were interviewed to ascertain eating disorder history. Seventeen per cent of mothers reported a history of eating disorder, compared with 3%–5% reported for community samples. A history of eating disorder was reported by 5.9% of mothers of children with SE, 12.9% of mothers of children with AN and 33.3% of mothers of children with FAED. The findings, based on this small sample, suggest that children with FAED are especially likely to have grown up in a dysfunctional food environment. Copyright © 2011 John Wiley & Sons, Ltd and Eating Disorders Association.     

Kinematic patterns for hindlimb obstacle avoidance during sheep locomotion

ABSTRACT

Functional recovery following general nerve reconstruction is often associated with poor results. Comparing to rat and mice experimental studies, there are much fewer investigations on nerve regeneration and repair in the sheep, and there are no studies on this subject using gait analysis in the sheep model as an assessment tool. Additionally, this is the first study evaluating obstacle negotiation and the compensatory strategies that take place at each joint in response to the obstacle during locomotion in the sheep model. This study aims to get kinematic data to serve as a template for an objective assessment of the ankle joint motion in future studies of common peroneal nerve (CP) injury and repair in the ovine model. Our results show that a moderately high obstacle set to 10% of the sheep’s hindlimb length was associated to several spatial and temporal strategies in order to increase hoof height during obstacle negotiating. Sheep efficiently cleared an obstacle by increasing knee, ankle and metatarsophalangeal flexion during swing, whereas the hip joint is not affected. This study establishes the bounds of normal motion in the neurologically intact hindlimb when approached and cleared an obstacle and provides baseline data for further studies of peripheral nerve research in the ovine model.     

Harm avoidance in adolescents modulates late positive potentials during affective picture processing

Research in adults has shown that individual differences in harm avoidance (HA) modulate electrophysiological responses to affective stimuli. To determine whether HA in adolescents modulates affective information processing, we collected event-related potentials from 70 adolescents while they viewed 90 pictures from the Chinese affective picture system. Multiple regressions revealed that HA negatively predicted late positive potential (LPP) for positive pictures and positively predicted for negative pictures; however, HA did not correlate with LPP for neutral pictures. The results suggest that at the late evaluative stage, high-HA adolescents display attentional bias to negative pictures while low-HA adolescents display attentional bias to negative pictures. Moreover, these dissociable attentional patterns imply that individual differences in adolescents’ HA modulate the late selective attention mechanism of affective information.     

Differential activation of anterior and midline thalamic nuclei following retrieval of aversively motivated learning tasks

Two thalamic nuclear groups, the anterior thalamic nuclei (ATN) and midline and intralaminar thalamic complex (MITC) have connections to the prefrontal cortex, amygdala, hippocampus and accumbens that are important for learning and memory. However, the anatomical proximity between the ATN and MITC makes it difficult to reveal their roles in memory retrieval of aversive conditioned behavior. To address the issue, we explored the activation of the ATN and MITC, as represented by the expression of the immediate early gene c-fos, following either the retrieval of a conditioned taste aversion (CTA) induced by taste-LiCl pairing (visceral aversion) or of inhibitory avoidance (IA) induced by context-foot shock pairing (somatic aversion) in rats. The anterodorsal (AD) nucleus in the ATN was activated by foot shock and the recall of IA, but not by i.p. injection of LiCl or the recall of CTA. No significant elevation was observed in the other ATN following these treatments. Among nuclei of the MITC, the paraventricular thalamic nucleus (PVT) was activated by the delivery of shock or LiCl and by the recall of both CTA and IA, while the mediodorsal thalamus (MD) and central medial and intermediate thalamus (CM/IMD) were not. The innately aversive taste of quinine did not elevate c-fos expression in either the ATN or MITC. These results suggest that the PVT in the MITC is involved in the processing and retrieval of both taste-malaise and context-shock association tasks, while the AD in the ATN is involved in those of context-shock association only. The difference of the activity between the ATN and MITC demonstrates their functional and anatomical heterogeneity in neural substrates for aversive learning tasks.     

Epinephrine-induced enhancement of memory retrieval for inhibitory avoidance conditioning in preweanling Sprague-Dawley rats

Developmental research on memory is commonly conducted using preweanling rats, but the extent to which these animals are susceptible to hormone-induced memory retrieval is unclear. This study examined the effects of epinephrine (.001, .01, or .1 mg/kg) on retrieval of IA conditioning in 17-day-old infants. Animals tested 24 hr following training performed significantly worse than infants tested 5 min after training and adults tested 24 hr later, indicating that infantile amnesia had occurred. Epinephrine attenuated this deficit in a dose-dependent manner, with a significant improvement in performance at doses of .01 mg/kg for latency and at .01 and .1 mg/kg for safe side-dependent measures. The role of epinephrine as a memory modulator is discussed in terms of its neurobiological and internal contextual effects.     

Cognitive defusion versus experiential avoidance in the reduction of smoking behaviour: an experimental and preliminary investigation

Background: Brief procedures that reduce smoking behaviour may be useful in reaching the many people that do not seek help for smoking addiction.

Objectives: The current study aimed to determine if one component of Acceptance and Commitment Therapy (ACT), cognitive defusion, could be useful in reducing smoking behaviour in a sample of students.

Methods: The study employed a between-subjects three-arm design. For one week, participants were asked to reduce their cigarette consumption. To aid them in their reduction, participants were randomly allocated to one of three conditions: the first received a defusion procedure, the second received an experiential avoidance procedure and a control condition received no procedure. For a second week, the instruction to reduce cigarette consumption was lifted. During both weeks participants were required to monitor their smoking behaviour via a tally diary system.

Results: The defusion condition smoked significantly less than the control condition during week one and significantly less than the control and experiential avoidance conditions during week two.

Conclusion: Results are discussed in terms of the potential utility of defusion in this domain, and the limitations of this preliminary research that would need to be addressed in future investigations.     

Vagus nerve stimulation-induced cognitive enhancement: Hippocampal neuroplasticity in healthy male rats

BackgroundVagus nerve stimulation (VNS) improves cognition in humans and rodents, but the effects of a single session of VNS on performance and plasticity are not well understood.ObjectiveBehavioral performance and hippocampal (HC) electrophysiology/neurotrophin expression were measured in healthy adult rats after VNS paired training to investigate changes in cognition and synaptic plasticity.MethodsPlatinum/iridium electrodes were surgically implanted around the left cervical branch of the VN of anesthetized male Sprague-Dawley rats (N = 47). VNS (100 μs biphasic pulses, 30 Hz, 0.8 mA) paired Novel Object Recognition (NOR)/Passive Avoidance Task (PAT) were assessed 24 h after training and post-mortem tissue was collected 48 h after VNS (N = 28). Electrophysiology recordings were collected using a microelectrode array system to assess functional effects on HC slices 90 min after VNS (N = 19). Sham received the same treatment without VNS and experimenters were blinded.ResultsStimulated rats exhibited improved performance in NOR (p < 0.05, n = 12) and PAT (p < 0.05, n = 14). VNS enhanced long-term potentiation (p < 0.05, n = 7–12), and spontaneous spike amplitude (p < 0.05, n = 7–12) and frequency (p < 0.05, n = 7–12) in the CA1. Immunohistochemical analysis found increased brain-derived neurotrophic factor expression in the CA1 (p < 0.05, n = 8–9) and CA2 (p < 0.01, n = 7–8).ConclusionThese findings suggest that our VNS parameters promote synaptic plasticity and target the CA1, which may mediate the positive cognitive effects of VNS. This study significantly contributes to a better understanding of VNS mediated HC synaptic plasticity, which may improve clinical utilization of VNS for cognitive enhancement.