A high and low fear phenotype mouse model

Fear-related illnesses such as post-traumatic stress disorder (PTSD) impose a tremendous burden on individual quality of life, families, and the national economy. In the military population, 17-20% of services members returning from deployment are diagnosed with PTSD. While treatments have improved for PTSD and are helpful for some, many people continue to suffer despite therapy. The aim of this research is to examine fear memory behaviourally and at the cellular level in the amygdala by using a unique inter-cross strain of high and low fear phenotype mice. An extended outcross C57BL/6J x DBA/2J (F8) are selected for high or low Pavlovian fear memory to context and cue. On presentation of either the original learning context or the cue (tone) mice display high or low levels of freezing as a behavioural measure of fear. In order to identify key aspects of the cellular basis of this difference in fear memory behaviour we are making measurements of protein levels and neuron numbers of a known pathway involved in the consolidation of a long term fear memory (pMAPK). Ongoing studies aim to determine if high fear behaviour is associated with differential signalling in the lateral amygdala compared to low fear behaviour. Additionally, by blocking this pathway in the lateral amygdala (LA), we aim to reduce fear behaviour following Pavlovian fear conditioning. This research will help to unravel the cellular mechanisms underlying high fear behaviour and advance the field toward targeted treatment and improved outcomes, ultimately improving human quality of life.

Functional neuroanatomy of auditory mismatch processing : an event-related fMRI study of duration-deviant oddballs

This study was designed to identify the neural networks underlying automatic auditory deviance detection in 10 healthy subjects using functional magnetic resonance imaging. We measured blood oxygenation level-dependent contrasts derived from the comparison of blocks of stimuli presented as a series of standard tones (50 ms duration) alone versus blocks that contained rare duration-deviant tones (100 ms) that were interspersed among a series of frequent standard tones while subjects were watching a silent movie. Possible effects of scanner noise were assessed by a “no tone” condition. In line with previous positron emission tomography and EEG source modeling studies, we found temporal lobe and prefrontal cortical activation that was associated with auditory duration mismatch processing. Data were also analyzed employing an event-related hemodynamic response model, which confirmed activation in response to duration-deviant tones bilaterally in the superior temporal gyrus and prefrontally in the right inferior and middle frontal gyri. In line with previous electrophysiological reports, mismatch activation of these brain regions was significantly correlated with age. These findings suggest a close relationship of the event-related hemodynamic response pattern with the corresponding electrophysiological activity underlying the event-related “mismatch negativity” potential, a putative measure of auditory sensory memory.

Disrupted sensory gating in pathological gambling

Background Some neurochemical evidence as well as recent studies on molecular genetics suggest that pathologic gambling may be related to dysregulated dopamine neurotransmission. Methods The current study examined sensory (motor) gating in pathologic gamblers as a putative measure of endogenous brain dopamine activity with prepulse inhibition of the acoustic startle eye-blink response and the auditory P300 event-related potential. Seventeen pathologic gamblers and 21 age- and gender-matched healthy control subjects were assessed. Both prepulse inhibition measures were recorded under passive listening and two-tone prepulse discrimination conditions. Results Compared to the control group, pathologic gamblers exhibited disrupted sensory (motor) gating on all measures of prepulse inhibition. Sensory motor gating deficits of eye-blink responses were most profound at 120-millisecond prepulse lead intervals in the passive listening task and at 240-millisecond prepulse lead intervals in the two-tone prepulse discrimination task. Sensory gating of P300 was also impaired in pathologic gamblers, particularly at 500-millisecond lead intervals, when performing the discrimination task on the prepulse. Conclusions In the context of preclinical studies on the disruptive effects of dopamine agonists on prepulse inhibition, our findings suggest increased endogenous brain dopamine activity in pathologic gambling in line with previous neurobiological findings.

Mice behaviorally selected for high Pavlovian fear memory exhibit fear generalization, HPA-axis alterations and increased basal activity in cortico-limbic circuits

Biological factors underlying individual variability in fearfulness and anxiety have important implications for stress-related psychiatric illness including PTSD and major depression. Using an advanced intercross line (AIL) derived from C57BL/6 and DBA/2J mouse strains and behavioral selection over 3 generations, we established two lines exhibiting High or Low fear behavior after fear conditioning. Across the selection generations, the two lines showed clear differences in training and tests for contextual and conditioned fear. Before fear conditioning training, there were no differences between lines in baseline freezing to a novel context. However, after fear conditioning High line mice demonstrated pronounced freezing in a new context suggestive of poor context discrimination. Fear generalization was not restricted to contextual fear. High fear mice froze to a novel acoustic stimulus while freezing in the Low line did not increase over baseline. Enhanced fear learning and generalization are consistent with transgenic and pharmacological disruption of the hypothalamic-pituitary-adrenal axis (HPA-axis) (Brinks, 2009, Thompson, 2004, Kaouane, 2012). To determine whether there were differences in HPA-axis regulation between the lines, morning urine samples were collected to measure basal corticosterone. Levels of secreted corticosterone in the circadian trough were analyzed by corticosterone ELISA. High fear mice were found to have higher basal corticosterone levels than low line animals. Examination of hormonal stress response components by qPCR revealed increased expression of CRH mRNA and decreased mRNA for MR and CRHR1 in hypothalamus of high fear mice. These alterations may contribute to both the behavioral phenotype and higher basal corticosterone in High fear mice. To determine basal brain activity in vivo in High and Low fear mice we used manganese-enhanced magnetic resonance imaging (MEMRI). Analysis revealed a pattern of basal brain activity made up of amygdala, cortical and hippocampal circuits that was elevated in the High line. Ongoing studies also seek to determine the relative balance of excitatory and inhibitory tone in the amygdala and hippocampus and the neuronal structure of its neurons. While these heterogeneous lines are selected on fear memory expression, HPA-axis alterations and differences in hippocampal activity segregate with the behavioral phenotypes. These differences are detectable in a basal state strongly suggesting these are biological traits underlying the behavioral phenotype (Johnson et al, 2011).

Neurobiological correlates of encoding strength of Pavlovian fear conditioned memory

Emotionally significant memories, especially those induced in conjunction with physical and mental trauma, are frequently retained for an individual’s lifetime. How these memories are organized and encoded within neural networks is a fundamental question. The lateral amygdala (LA) is a key nucleus for acquisition and maintenance of associative emotional memories. We used Pavlovian fear conditioning to study how ‘weaker’ and ‘stronger’ memories are encoded in neural networks of the LA. In Pavlovian fear conditioning a neutral stimulus, in this case a tone, is temporally paired with an aversive unconditioned stimulus (US), such as a foot shock. The previously neutral stimulus becomes a conditioned stimulus (CS) capable of eliciting defensive responses. We used time spent freezing when the CS is presented in a neutral context as a dependent variable measure of memory ‘strength’.

Systematic constellations of neurons are activated in lateral amygdala following Pavlovian fear conditioning

How memory is organized within neural networks is a fundamental question in neuroscience. We used Pavlovian fear conditioning to study the discrete organization patterns of neurons activated in an associative memory paradigm. In Pavlovian fear conditioning a neutral stimulus, such as an auditory tone, is temporally paired with an aversive unconditioned stimulus (US), such as a foot shock...

GABAa receptors contribute to synaptic integration in lateral amygdala neurons

In classical fear conditioning a neutral conditioned stimulus (CS) such as a tone, is paired with an aversive unconditioned stimulus (US) such as a shock. The CS thereby acquires the capacity to elicit a fear response. This type of associative learning is thought to require co-activation of principle neurons in the lateral nucleus of the amygdala (LA) by two sets of synaptic inputs, a weak CS and a strong US...

Association of hearing impairment and subsequent driving mobility in older adults

- Purpose of the study Hearing impairment (HI) is associated with driving safety (e.g., increased crashes and poor on-road driving performance). However, little is known about HI and driving mobility. This study examined the longitudinal association of audiometric hearing with older adults’ driving mobility over three years. - Design and Methods Secondary data analyses were conducted of 500 individuals (63-90 years) from the Staying Keen in Later Life (SKILL) study. Hearing (pure tone average of 0.5, 1, and 2 kHz) was assessed in the better hearing ear and categorized into normal hearing <25 dB HL; mild HI 26-40 dB HL; or moderate and greater HI>41 dB HL. The Useful Field of View Test (UFOV) was used to estimate the risk for adverse driving events. MANCOVA compared driving mobility between HI levels across time, adjusting for age, sex, race, hypertension, and stroke. Adjusting for these same covariates, Cox regression analyses examined incidence of driving cessation by HI across three years. - Results Individuals with moderate or greater HI performed poorly on the UFOV, indicating increased risk for adverse driving events (p<.001). No significant differences were found among older adults with varying levels of HI for driving mobility (ps>.05), including driving cessation rates (p=.38), across time. - Implications Although prior research indicates older adults with HI may be at higher risk for crashes, they may not modify driving over time. Further exploration of this issue is required to optimize efforts to improve driving safety and mobility among older adults.

Driver sleepiness on YouTube: A content analysis

Driver sleepiness is a major contributor to severe crashes and fatalities on our roads. Many people continue to drive despite being aware of feeling tired. Prevention relies heavily on education campaigns as it is difficult to police driver sleepiness. The video sharing social media site YouTube is extremely popular, particularly with at risk driver demographics. Content and popularity of uploaded videos can provide insight into the quality of publicly accessible driver sleepiness information. The purpose of this research was to answer two questions; firstly, how prevalent are driver sleepiness videos on YouTube? And secondly, what are the general characteristics of driver sleepiness videos in terms of (a) outlook on driver sleepiness, (b) tone, (c) countermeasures to driver sleepiness, and, (d) driver demographics. Using a keywords search, 442 relevant videos were found from a five year period (2nd December 2009–2nd December 2014). Tone, outlook, and countermeasure use were thematically coded. Driver demographic and video popularity data also were recorded. The majority of videos portrayed driver sleepiness as dangerous. However, videos that had an outlook towards driver sleepiness being amusing were viewed more often and had more mean per video comments and likes. Humorous videos regardless of outlook, were most popular. Most information regarding countermeasures to deal with driver sleepiness was accurate. Worryingly, 39.8% of videos with countermeasure information contained some kind of ineffective countermeasure. The use of humour to convey messages about the dangers of driver sleepiness may be a useful approach in educational interventions.

Development and feasibility testing of an education program to improve knowledge and self-care among Aboriginal and Torres Strait Islander patients with heart failure

Background/Aim There is a 70% higher age-adjusted incidence of heart failure (HF) amongst Aboriginal and Torres Strait Islander people, three times more hospitalisations and twice as many deaths than non-Aboriginal people. There is a need to develop holistic yet individualised approaches in accord with the values of Aboriginal community healthcare to support patient education and self-care. The aim of this study was to re-design an existing HF educational resource (Fluid Watchers-Pacific Rim©) to be culturally safe for Aboriginal and Torres Strait Islander peoples, working in collaboration with the local community, and to conduct feasibility testing. Methods This study was conducted in two phases and utilised a mixed methods approach (qualitative and quantitative). Phase 1 of this study used action research methods to develop a culturally safe electronic resource to be provided to Aboriginal HF patients via a tablet computer. A HF expert panel adapted the existing resource to ensure it was evidence-based and contained appropriate language and images that reflects Aboriginal culture. A stakeholder group (which included Aboriginal workers and HF patients, as well as researchers and clinicians) then reviewed the resources and changes were made accordingly. In Phase 2, the new resource was tested on a sample of Aboriginal HF patients to assess feasibility and acceptability. Patient knowledge, satisfaction and self-care behaviours were measured using a before and after design with validated questionnaires. As this was a pilot test to determine feasibility, no statistical comparisons were made. Results - Phase 1: Throughout the process of resource development, two main themes emerged from the stakeholder consultation. These were the importance of identity, meaning that it was important to ensure that the resource accurately reflected the local community, with the appropriate clothing, skin tone and voice. The resource was adapted to reflect this and of the local community voiced the recordings for the resource. The other theme was comprehension; images were important and all text was converted to the first person and used plain language. - Phase 2: Five Aboriginal participants, mean age 61.6 ± 10.0 years, with NYHA Class III and IV heart failure were enrolled. Participants reported a high level of satisfaction with the resource (83.0%). HF knowledge (percentage of correct responses) increased from 48.0 ± 6.7% to 58.0 ± 9.7%, a 20.8% increase and results of the self-care index indicated that the biggest change was in patient confidence for self-care with a 95% increase in confidence score (46.7 ± 16.0 to 91.1 ± 11.5). Changes in management and maintenance scores varied between9275 patients. Conclusion By working in collaboration with HF experts, Aboriginal researchers and patients, a culturally safe HF resource has been developed for Aboriginal and Torres Strait Islander patients. Engaging Aboriginal researchers, capacity-building, and being responsive to local systems and structures enabled this pilot study to be successfully completed with the Aboriginal community and positive participant feedback demonstrated that the methodology used in this study was appropriate and acceptable; participants were able to engage with willingness and confidence.

Mammalian reverse genetics without crossing reveals Nr3a as a short-sleeper gene

The identification of molecular networks at the system level in mammals is accelerated by next-generation mammalian genetics without crossing, which requires both the efficient production of whole-body biallelic knockout (KO) mice in a single generation and high-performance phenotype analyses. Here, we show that the triple targeting of a single gene using the CRISPR/Cas9 system achieves almost perfect KO efficiency (96%–100%). In addition, we developed a respiration-based fully automated noninvasive sleep phenotyping system, the Snappy Sleep Stager (SSS), for high-performance (95.3% accuracy) sleep/wake staging. Using the triple-target CRISPR and SSS in tandem, we reliably obtained sleep/wake phenotypes, even in double-KO mice. By using this system to comprehensively analyze all of the N-methyl-D-aspartate (NMDA) receptor family members, we found Nr3a as a short-sleeper gene, which is verified by an independent set of triple-target CRISPR. These results demonstrate the application of mammalian reverse genetics without crossing to organism-level systems biology in sleep research.

Pictures that ask the right questions

An article about the use of photographs as research in the writing of memoir. "I expect many people begin the writing of a memoir by looking through old photos. Pictures, after all, belong in the past, and they hold out the promise of delivering it to us again: everyone is younger, surrounded by yesterday’s world, a moment fixed in time. Even the size of the photo paper and printing tone belong back there, in a printer’s shop that doesn’t exist anymore. And yet, for the purpose of writing a memoir, the most useful pictures also reach beyond the past, and beyond their initial role in verifying your memories, or filling out the details. That is, they are more than an account. Such pictures seem to be asking questions about what happened next, in the moments and years after they were taken..."

Involvement of Ca2+-dependent hyperpolarization in sleep duration in mammals

The detailed molecular mechanisms underlying the regulation of sleep duration in mammals are still elusive. To address this challenge, we constructed a simple computational model, which recapitulates the electrophysiological characteristics of the slow-wave sleep and awake states. Comprehensive bifurcation analysis predicted that a Ca2+-dependent hyperpolarization pathway may play a role in slow-wave sleep and hence in the regulation of sleep duration. To experimentally validate the prediction, we generate and analyze 21 KO mice. Here we found that impaired Ca2+-dependent K+ channels (Kcnn2 and Kcnn3), voltage-gated Ca2+ channels (Cacna1g and Cacna1h), or Ca2+/calmodulin-dependent kinases (Camk2a and Camk2b) decrease sleep duration, while impaired plasma membrane Ca2+ ATPase (Atp2b3) increases sleep duration. Pharmacological intervention and whole-brain imaging validated that impaired NMDA receptors reduce sleep duration and directly increase the excitability of cells. Based on these results, we propose a hypothesis that a Ca2+-dependent hyperpolarization pathway underlies the regulation of sleep duration in mammals.