Evaluation of two methods to isolate Schwann cells from murine sciatic nerve.

BACKGROUND: Schwann cells (SC) and macrophages play key roles in the response to peripheral nerve injury (PNI). Accurate isolation of such cells is essential for further analyses that can lead to better understanding of the repair process after PNI. Separation of live SC from the injury site without culture enrichment is necessary for targeted gene expression analysis. NEW METHODS: Two flow cytometric techniques are presented for rapid enrichment of live SC and macrophages from injured murine peripheral nerve without the need for culture. RESULTS: SC were isolated by fluorescent activated cell sorting (FACS) using transgenic expression of eGFP in SC, or by exclusion of other cell types collected from the injury site. COMPARISON WITH EXISTING METHOD(S): Gene expression analyses of peripheral nerve repair have commonly used whole nerve lysates. Isolating SC allows more accurate understanding of their specific role in repair. SC are commonly enriched from nerve by culture, however this changes gene expression patterns and limits the utility for transcriptomic analysis. The surface marker p75-NTR has variable expression in different SC phenotypes and during the course of injury and repair. Using p75-NTR for SC isolation might enrich only a subset of SC. More stably expressed lineage markers for SC are intracellular and not suitable for sorting for gene expression. The methods used here avoid the requirement for surface marker labeling of SC. CONCLUSION: Gene expression analysis of sorted cells from both methods showed successful enrichment of SC. Lineage markers such as Map1b, p75-NTR and S100b were enriched in the sorted SC population. SC sorting by eGFP expression showed improved enrichment, particularly of mature myelinating genes, although this could represent sampling of a subset of SC.

Flexible combination of reward information across primates.

A fundamental but rarely contested assumption in economics and neuroeconomics is that decision-makers compute subjective values of risky options by multiplying functions of reward probability and magnitude. By contrast, an additive strategy for valuation allows flexible combination of reward information required in uncertain or changing environments. We hypothesized that the level of uncertainty in the reward environment should determine the strategy used for valuation and choice. To test this hypothesis, we examined choice between risky options in humans and rhesus macaques across three tasks with different levels of uncertainty. We found that whereas humans and monkeys adopted a multiplicative strategy under risk when probabilities are known, both species spontaneously adopted an additive strategy under uncertainty when probabilities must be learned. Additionally, the level of volatility influenced relative weighting of certain and uncertain reward information, and this was reflected in the encoding of reward magnitude by neurons in the dorsolateral prefrontal cortex.

Motor thalamus supports striatum-driven reinforcement.

Reinforcement has long been thought to require striatal synaptic plasticity. Indeed, direct striatal manipulations such as self-stimulation of direct-pathway projection neurons (dMSNs) are sufficient to induce reinforcement within minutes. However, it's unclear what role, if any, is played by downstream circuitry. Here, we used dMSN self-stimulation in mice as a model for striatum-driven reinforcement and mapped the underlying circuitry across multiple basal ganglia nuclei and output targets. We found that mimicking the effects of dMSN activation on downstream circuitry, through optogenetic suppression of basal ganglia output nucleus substantia nigra reticulata (SNr) or activation of SNr targets in the brainstem or thalamus, was also sufficient to drive rapid reinforcement. Remarkably, silencing motor thalamus-but not other selected targets of SNr-was the only manipulation that reduced dMSN-driven reinforcement. Together, these results point to an unexpected role for basal ganglia output to motor thalamus in striatum-driven reinforcement.

Volatility Facilitates Value Updating in the Prefrontal Cortex.

Adaptation of learning and decision-making might depend on the regulation of activity in the prefrontal cortex. Here we examined how volatility of reward probabilities influences learning and neural activity in the primate prefrontal cortex. We found that animals selected recently rewarded targets more often when reward probabilities of different options fluctuated across trials than when they were fixed. Additionally, neurons in the orbitofrontal cortex displayed more sustained activity related to the outcomes of their previous choices when reward probabilities changed over time. Such volatility also enhanced signals in the dorsolateral prefrontal cortex related to the current but not the previous location of the previously rewarded target. These results suggest that prefrontal activity related to choice and reward is dynamically regulated by the volatility of the environment and underscore the role of the prefrontal cortex in identifying aspects of the environment that are responsible for previous outcomes and should be learned.

Metaplasticity as a Neural Substrate for Adaptive Learning and Choice under Uncertainty.

Value-based decision making often involves integration of reward outcomes over time, but this becomes considerably more challenging if reward assignments on alternative options are probabilistic and non-stationary. Despite the existence of various models for optimally integrating reward under uncertainty, the underlying neural mechanisms are still unknown. Here we propose that reward-dependent metaplasticity (RDMP) can provide a plausible mechanism for both integration of reward under uncertainty and estimation of uncertainty itself. We show that a model based on RDMP can robustly perform the probabilistic reversal learning task via dynamic adjustment of learning based on reward feedback, while changes in its activity signal unexpected uncertainty. The model predicts time-dependent and choice-specific learning rates that strongly depend on reward history. Key predictions from this model were confirmed with behavioral data from non-human primates. Overall, our results suggest that metaplasticity can provide a neural substrate for adaptive learning and choice under uncertainty.

A Direct Path to Action Initiation.

In this issue of Neuron, Sippy et al. (2015) provide the clearest evidence to date that information is differentially encoded in the direct and indirect pathways of the striatum. The results support the classical notion that the direct pathway plays a critical role in initiating actions.

Dynamic routing of task-relevant signals for decision making in dorsolateral prefrontal cortex.

Neurons in the dorsolateral prefrontal cortex (DLPFC) encode a diverse array of sensory and mnemonic signals, but little is known about how this information is dynamically routed during decision making. We analyzed the neuronal activity in the DLPFC of monkeys performing a probabilistic reversal task where information about the probability and magnitude of reward was provided by the target color and numerical cues, respectively. The location of the target of a given color was randomized across trials and therefore was not relevant for subsequent choices. DLPFC neurons encoded signals related to both task-relevant and irrelevant features, but only task-relevant mnemonic signals were encoded congruently with choice signals. Furthermore, only the task-relevant signals related to previous events were more robustly encoded following rewarded outcomes. Thus, multiple types of neural signals are flexibly routed in the DLPFC so as to favor actions that maximize reward.

Neural correlates of strategic reasoning during competitive games.

Although human and animal behaviors are largely shaped by reinforcement and punishment, choices in social settings are also influenced by information about the knowledge and experience of other decision-makers. During competitive games, monkeys increased their payoffs by systematically deviating from a simple heuristic learning algorithm and thereby countering the predictable exploitation by their computer opponent. Neurons in the dorsomedial prefrontal cortex (dmPFC) signaled the animal's recent choice and reward history that reflected the computer's exploitative strategy. The strength of switching signals in the dmPFC also correlated with the animal's tendency to deviate from the heuristic learning algorithm. Therefore, the dmPFC might provide control signals for overriding simple heuristic learning algorithms based on the inferred strategies of the opponent.

A randomized, placebo-controlled trial of N-acetylcysteine plus imaginal desensitization for nicotine-dependent pathological gamblers.

OBJECTIVE: Pathological gambling is associated with elevated proportions of nicotine dependence, and tobacco smoking in pathological gamblers has been associated with increased problem-gambling severity. This study examined the addition of N-acetylcysteine to imaginal desensitization in adults with co-occurring nicotine dependence and pathological gambling. METHOD: Twenty-eight individuals with co-occurring DSM-IV nicotine dependence and pathological gambling who were receiving behavioral therapy were recruited from December 2009 to February 2012 and randomized to augmentation with N-acetylcysteine or placebo in an 12-week, double-blind trial. Subjects were assessed with measures of nicotine and gambling severity and followed for 3 months after treatment. The primary outcomes were the Fagerström Test for Nicotine Dependence and the pathological gambling adaptation of the Yale-Brown Obsessive-Compulsive Scale. RESULTS: During the first 6 weeks, there was a significant benefit of N-acetylcysteine treatment versus placebo on Fagerström Test for Nicotine Dependence total scores (t = -2.224; P = .031). After the initial 6 weeks, all subjects significantly (P < .001) benefited from imaginal desensitization. During the 3-month follow-up, there was a significant additional benefit for N-acetylcysteine versus placebo on measures of problem-gambling severity (t = 2.069; P = .043). CONCLUSIONS: N-acetylcysteine treatment during therapy facilitates long-term application of behavioral therapy techniques once patients are in the community after therapy has been completed. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00967005.

Cortical signals for rewarded actions and strategic exploration.

In stable environments, decision makers can exploit their previously learned strategies for optimal outcomes, while exploration might lead to better options in unstable environments. Here, to investigate the cortical contributions to exploratory behavior, we analyzed single-neuron activity recorded from four different cortical areas of monkeys performing a matching-pennies task and a visual search task, which encouraged and discouraged exploration, respectively. We found that neurons in multiple regions in the frontal and parietal cortex tended to encode signals related to previously rewarded actions more reliably than unrewarded actions. In addition, signals for rewarded choices in the supplementary eye field were attenuated during the visual search task and were correlated with the tendency to switch choices during the matching-pennies task. These results suggest that the supplementary eye field might play a unique role in encouraging animals to explore alternative decision-making strategies.

Adolescent stealing treated with motivational interviewing and imaginal desensitization - Case report.

Background Adolescent shoplifting occurs in an estimated 15% of the United States population. Although adolescent stealing is associated with significant psychosocial consequences there is limited research concerning efficacious treatments. Case study A 17-year-old male with a history of compulsive stealing was treated using a six-session, individualized cognitive-behavioral therapy protocol which included motivational interviewing, psycho-education, behavioral modification, and an exposure script using imaginal desensitization. After the six-session therapy, the patient continued for eight further sessions of therapy to maintain treatment gains. His Yale-Brown Obsessive Compulsive Scale scores dropped from a 22 pre-treatment to a 3 at the end of the 14 sessions of therapy and he remained abstinent from stealing. Discussion This case reports on the successful use of an individualized, cognitive behavioral therapy on an adolescent with compulsive shoplifting and other antisocial behaviors. This treatment provides a promising step towards the treatment of a relatively common adolescent behavior.

Genome-wide profiling of H3K56 acetylation and transcription factor binding sites in human adipocytes.

The growing epidemic of obesity and metabolic diseases calls for a better understanding of adipocyte biology. The regulation of transcription in adipocytes is particularly important, as it is a target for several therapeutic approaches. Transcriptional outcomes are influenced by both histone modifications and transcription factor binding. Although the epigenetic states and binding sites of several important transcription factors have been profiled in the mouse 3T3-L1 cell line, such data are lacking in human adipocytes. In this study, we identified H3K56 acetylation sites in human adipocytes derived from mesenchymal stem cells. H3K56 is acetylated by CBP and p300, and deacetylated by SIRT1, all are proteins with important roles in diabetes and insulin signaling. We found that while almost half of the genome shows signs of H3K56 acetylation, the highest level of H3K56 acetylation is associated with transcription factors and proteins in the adipokine signaling and Type II Diabetes pathways. In order to discover the transcription factors that recruit acetyltransferases and deacetylases to sites of H3K56 acetylation, we analyzed DNA sequences near H3K56 acetylated regions and found that the E2F recognition sequence was enriched. Using chromatin immunoprecipitation followed by high-throughput sequencing, we confirmed that genes bound by E2F4, as well as those by HSF-1 and C/EBPα, have higher than expected levels of H3K56 acetylation, and that the transcription factor binding sites and acetylation sites are often adjacent but rarely overlap. We also discovered a significant difference between bound targets of C/EBPα in 3T3-L1 and human adipocytes, highlighting the need to construct species-specific epigenetic and transcription factor binding site maps. This is the first genome-wide profile of H3K56 acetylation, E2F4, C/EBPα and HSF-1 binding in human adipocytes, and will serve as an important resource for better understanding adipocyte transcriptional regulation.

A 6-month follow-up of imaginal desensitization plus motivational interviewing in the treatment of pathological gambling.

BACKGROUND: Pathological gambling (PG), a disabling disorder experienced by approximately 1% of adults, has few empirically validated treatments. A recent study demonstrated that 6 sessions of imaginal desensitization plus motivational interviewing (IDMI) was effective in achieving abstinence for a majority of individuals with PG. This study sought to examine whether those benefits were maintained 6 months post-treatment. METHODS: Sixty-eight individuals who met DSM-IV criteria for PG were randomly assigned to 6 sessions of IDMI or Gamblers Anonymous (GA) referral over an 8-week period. Participants who failed to respond to GA were offered IDMI after the 8-week acute treatment period. All individuals who responded to IDMI were contacted after 6 months and assessed with measures of gambling severity and psychosocial functioning. RESULTS: Forty-four participants completed 6 sessions of IDMI (25 initially assigned to IDMI and 19 to GA). Thirty-five of the 44 (79.5%) responded during acute treatment, and all 35 were available for a 6-month evaluation. All gambling severity scales maintained statistically significant gains from baseline, although some measures showed significant worsening compared with post-IDMI treatment. CONCLUSIONS: Six sessions of IDMI resulted in statistically significant reductions in PG urges and behavior, which were largely maintained for 6 months.

Somatosensory responses in normal aging, mild cognitive impairment, and Alzheimer's disease.

As a part of a larger study of normal aging and Alzheimer's disease (AD), which included patients with mild cognitive impairment (MCI), we investigated the response to median nerve stimulation in primary and secondary somatosensory areas. We hypothesized that the somatosensory response would be relatively spared given the reported late involvement of sensory areas in the progression of AD. We applied brief pulses of electric current to left and right median nerves to test the somatosensory response in normal elderly (NE), MCI, and AD. MEG responses were measured and were analyzed with a semi-automated source localization algorithm to characterize source locations and timecourses. We found an overall difference in the amplitude of the response of the primary somatosensory source (SI) based on diagnosis. Across the first three peaks of the SI response, the MCI patients exhibited a larger amplitude response than the NE and AD groups (P < 0.03). Additional relationships between neuropsychological measures and SI amplitude were also determined. There was no significant difference in amplitude for the contralateral secondary somatosensory source across diagnostic category. These results suggest that somatosensory cortex is affected early in the progression of AD and may have some consequence on behavioral and functional measures.

Imaginal desensitisation plus motivational interviewing for pathological gambling: randomised controlled trial.

Sixty-eight individuals were randomised to either six sessions of imaginal desensitisation plus motivational interviewing (IDMI) or Gamblers Anonymous. Individuals assigned to IDMI had significantly greater reductions in Yale-Brown Obsessive Compulsive Scale Modified for Pathological Gambling total scores, gambling urges and gambling behaviour. People who failed to respond to Gamblers Anonymous reported significantly greater reduction in pathological gambling symptoms following later assignment to IDMI. Abstinence was achieved by 63.6% during the acute IDMI treatment period.

Cognitive-behavioral therapy for panic disorder in patients being treated for alcohol dependence: Moderating effects of alcohol outcome expectancies.

Anxiety disorders commonly co-occur with alcohol use disorders and reliably mark a poor response to substance abuse treatment. However, treating a co-occurring anxiety disorder does not reliably improve substance abuse treatment outcomes. Failure to account for individual differences in the functional dynamic between anxiety symptoms and drinking behavior might impede the progress and clarity of this research program. For example, while both theory and research point to the moderating role of tension-reduction alcohol outcome expectancies (TR-AOEs) in the association between anxiety symptoms and alcohol use, relevant treatment studies have not typically modeled TR-AOE effects. We examined the impact of a hybrid cognitive-behavioral therapy (H-CBT) treatment for panic disorder (independent variable) on response to a community-based alcohol dependence treatment program (dependent variable) in patients with higher vs. lower TR-AOEs (moderator). The H-CBT treatment was generally effective in relieving participants' panic symptoms relative to controls. However, TR-AOEs interacted with study cohort (H-CBT vs. control) in predicting response to substance abuse treatment. As expected, the H-CBT was most effective in improving alcohol use outcomes among those with the highest TR-AOEs. The study's primary methodological limitations are related to the quasi-experimental design employed.

Effect of quetiapine vs. placebo on response to two virtual public speaking exposures in individuals with social phobia.

OBJECTIVE: Clinical practice and open-label studies suggest that quetiapine (an atypical anti-psychotic) might improve symptoms for individuals with social anxiety disorder (SAD). The purpose of this study was to provide a rigorous test of the acute impact of a single dose of quetiapine (25mg) on SAD symptoms. METHOD: Individuals with SAD (N=20) were exposed to a 4-min virtual reality (VR) public speaking challenge after having received quetiapine or placebo (double-blind) 1h earlier. A parallel VR challenge occurred 1 week later using a counter-balanced cross-over (within subject) design for the medication-placebo order between the two sessions. RESULT: There was no significant drug effect for quetiapine on the primary outcome measures. However, quetiapine was associated with significantly elevated heart rate and sleepiness compared with placebo. CONCLUSION: Study findings suggest that a single dose of 25mg quetiapine is not effective in alleviating SAD symptoms in individuals with fears of public speaking.

Physiological response to a speech stressor presented in a virtual reality environment.

The feasibility of using virtual reality (VR) technology to induce a physiological response to stress was assessed in 12 volunteers during a laboratory session in which each participant completed a speech task within a VR environment and a math task outside the VR environment. Both tasks were effective in eliciting a physiological response with significant increases observed in response to each stress task in systolic and diastolic blood pressure and heart rate. Increases in plasma epinephrine and norepinephrine concentrations were observed during the speech task and in plasma epinephrine concentrations during the math task although these differences did not reach statistical significance. The use of VR technology may be a viable alternative to methods currently employed in presenting stressful tasks with the potential advantage of decreased variability in the audience response to the participants' performance.

Development of a robust GABA(B) calcium signaling cell line using beta-lactamase technology and sorting.

The GABA(B) receptor is a member of the "family 3" G protein coupled receptors. The GABA(B) receptors modulate activity inwardly rectifying potassium channels and high voltage activated calcium channels. The GABA(B) receptors require heterodimerization between two subunits, GABA(B1) and GABA(B2), for functional expression. A robust functional calcium cell line was developed that contained both the human truncated GABA(B(1b)) and human truncated GABA(B(2)) receptors. The cell line was analyzed and sorted using beta-lactamase as a reporter. Single cell clones were sorted and isolated using flow cytometry based on high beta-lactamase expression. The single cell clones were further tested in a 384-well calcium mobilization assay using the Fluo-4 AM calcium indicator on the fluorescent imaging plate reader system (FLIPR). Twenty-seven clones were grown up from single cell collections and 10 clones demonstrated a high response to GABA stimulation. The 10 clones were re-evaluated based on agonist dose response and EC(50). Clone-16 was identified and utilized in high throughput screening (HTS) assay development. Using sorting and beta-lactamase as a reporter, we were able to develop a robust, functional cell-based, GABA(B), calcium mobilization assay. The cell line described here can be used for high throughput FLIPR screening and also to compare and rank the potency and selectivity of agonists, antagonists and potentiators of the GABA(B) receptor.