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.     

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.     

Computation of avoidance regions for driver assistance systems by using a Hamilton-Jacobi approach

We consider the problem of computing safety regions, modeled as nonconvex backward reachable sets, for a nonlinear car collision avoidance model with time-dependent obstacles. The Hamilton-Jacobi-Bellman framework is used. A new formulation of level set functions for obstacle avoidance is given, and sufficient conditions for granting the obstacle avoidance on the whole time interval are obtained even though the conditions are checked only at discrete times. Different scenarios, including various road configurations, different geometry of vehicle and obstacles, as well as fixed or moving obstacles, are then studied and computed. Computations involve solving nonlinear partial differential equations of up to five space dimensions plus time with nonsmooth obstacle representations, and an efficient solver is used to this end. A comparison with a direct optimal control approach is also done for one of the examples.     

The cost of fear: Avoidant decision making in a spider gambling task

Individuals with anxiety disorders typically avoid fear-relevant stimuli even if they miss potential rewards. However, few studies have accounted for such costs of fear-related avoidance in doing so. In this study, 51 spider fearful and 49 non-fearful participants completed the Spider Gambling Task, our modification of the Iowa Gambling Task, to investigate whether fear-relevant stimuli trigger avoidant decisions in the presence of potential rewards. In one version, advantageous choices were associated with pictures of spiders, whereas the same pictures were associated with disadvantageous choices in another version. Fearful participants generally avoided choices associated with pictures of spiders, which resulted in lower overall gains in the version with advantageous spider decks. Although this relative avoidance was sustained, fearful participants progressively approach more advantageous spider choices. These findings demonstrate that phobic fear results in irrational avoidant decisions which can result in considerable cost. Potential long-term rewards for approach may, however, diminish absolute avoidance behavior.     

Fear-avoidance beliefs—a moderator of treatment efficacy in patients with low back pain: a systematic review

Background contextPsychological factors are believed to influence the development of chronic low back pain. To date, it is not known how fear-avoidance beliefs (FABs) influence the treatment efficacy in low back pain.PurposeTo summarize the evidence examining the influence of FABs measured with the Fear-Avoidance Belief Questionnaire or the Tampa Scale of Kinesiophobia on treatment outcomes in patients with low back pain.Study design/settingThis is a systematic review.Patient samplePatients with low back pain.Outcome measuresWork-related outcomes and perceived measures including return to work, pain, and disability.MethodsIn January 2013, the following databases were searched: BIOSIS, CINAHL, Cochrane Library, Embase, OTSeeker, PeDRO, PsycInfo, PubMed/Medline, Scopus, and Web of Science. A hand search of the six most often retrieved journals and a bibliography search completed the search. Study eligibility criteria, participants, and interventions: research studies that included patients with low back pain who participated in randomized controlled trials (RCTs) investigating nonoperative treatment efficacy. Out of 646 records, 78 articles were assessed in full text and 17 RCTs were included. Study quality was high in five studies and moderate in 12 studies.ResultsIn patients with low back pain of up to 6 months duration, high FABs were associated with more pain and/or disability (4 RCTs) and less return to work (3 RCTs) (GRADE high-quality evidence, 831 patients vs. 322 in nonpredictive studies). A decrease in FAB values during treatment was associated with less pain and disability at follow-up (GRADE moderate evidence, 2 RCTs with moderate quality, 242 patients). Interventions that addressed FABs were more effective than control groups based on biomedical concepts (GRADE moderate evidence, 1,051 vs. 227 patients in studies without moderating effects). In chronic patients with LBP, the findings were less consistent. Two studies found baseline FABs to be associated with more pain and disability and less return to work (339 patients), whereas 3 others (832 patients) found none (GRADE low evidence). Heterogeneity of the studies impeded a pooling of the results.ConclusionsEvidence suggests that FABs are associated with poor treatment outcome in patients with LBP of less than 6 months, and thus early treatment, including interventions to reduce FABs, may avoid delayed recovery and chronicity. Patients with high FABs are more likely to improve when FABs are addressed in treatments than when these beliefs are ignored, and treatment strategies should be modified if FABs are present.     

Psychiatric symptoms in boys with fragile X syndrome: A comparison with nonsyndromic autism spectrum disorder

In the present study, we examined the profile of psychiatric symptoms in boys with fragile X syndrome (FXS) using a parent report instrument. In addition, by comparing boys with FXS to boys with nonsyndromic autism spectrum disorder (ASD) utilizing multiple matching strategies, we examined between-group differences in the types of psychiatric symptoms observed and in the strength of their concurrent associations. Across all matching strategies, symptoms of manic/hyperactive behaviors and general anxiety were more frequently reported for boys with FXS than for boys with nonsyndromic ASD. Results also indicated a positive association between social avoidance and general anxiety in FXS that was stronger than that observed in nonsyndromic ASD across all matching strategies. Theoretical and treatment implications are discussed.     

The neural correlates of worry in association with individual differences in neuroticism

The tendency to worry is a facet of neuroticism that has been shown to mediate the relationship between neuroticism and symptoms of depression and anxiety. The aim of the current study was to investigate the neural correlates of state worry in association with neuroticism. One‐hundred twenty participants were selected from an initially recruited sample of 240 women based on their neuroticism score. First, participants completed a questionnaire to assess the excessiveness and uncontrollability of pathological worry. Second, we measured brain activation with functional magnetic resonance imaging (fMRI) while participants were randomly presented with 12 worry‐inducing sentences and 12 neutral sentences in a mood induction paradigm. Individuals scoring higher on neuroticism reported to worry more in daily life and to have generated more worry‐related thoughts after the presentation of a worry‐inducing sentence. Furthermore, imaging results showed the involvement of default mode and emotional brain areas during worry, previously associated with self‐related processing and emotion regulation. Specifically, cortical midline structures and the anterior insula showed more activation during worry, when individuals indicated to have generated more worry‐related thoughts. Activation in the retrosplenial and visual cortex was decreased in individuals scoring higher on neuroticism during worry, possibly suggesting reduced autobiographical specificity and visual mental imagery. In the literature, both these processes have been related to the cognitive avoidance of emotional distress. Excessive worry features in a number of emotional disorders and results from studies that elucidate its neural basis may help explain how and why neuroticism contributes to vulnerability for psychopathology. Hum Brain Mapp 35:4303–4315, 2014. © 2014 Wiley Periodicals, Inc .