Instrumental Behavior Research Articles

Features in air ions measured by an air ion spectrometer (AIS) at Dome C

Abstract. An air ion spectrometer (AIS) was deployed for the first time at the Concordia station at Dome C (75°06′ S, 123°23′ E; 3220 m a. s. l. ), Antarctica during the period 22 December 2010–16 November 2011 for measuring the number size distribution of air ions. In this work, we present results obtained from this air ion data set together with aerosol particle and meteorological data. The main processes that modify the number size distribution of air ions during the measurement period at this high-altitude site included new particle formation (NPF, observed on 85 days), wind-induced ion formation (observed on 36 days), and ion production and loss associated with cloud/fog formation (observed on 2 days). For the subset of days when none of these processes seemed to operate, the concentrations of cluster ions (0.9–1.9 nm) exhibited a clear seasonality, with high concentrations in the warm months and low concentrations in the cold. Compared to event-free days, days with NPF were observed with higher cluster ion concentrations. A number of NPF events were observed with restricted growth below 10 nm, which were termed as suppressed NPF. There was another distinct feature, namely a simultaneous presence of two or three separate NPF and subsequent growth events, which were named as multi-mode NPF events. Growth rates (GRs) were determined using two methods: the appearance time method and the mode fitting method. The former method seemed to have advantages in characterizing NPF events with a fast GR, whereas the latter method is more suitable when the GR was slow. The formation rate of 2 nm positive ions (J2+) was calculated for all the NPF events for which a GR in the 2–3 nm size range could be determined. On average, J2+ was about 0.014 cm−3 s−1. The ion production in relation to cloud/fog formation in the size range of 8–42 nm seemed to be a unique feature at Dome C, which has not been reported elsewhere. These ions may, however, either be multiply charged particles but detected as singly charged in the AIS, or be produced inside the instrument, due to the breakage of cloud condensation nuclei (CCN), possibly related to the instrumental behaviour under the extremely cold condition. For the wind-induced ion formation, our observations suggest that the ions originated more likely from atmospheric nucleation of vapours released from the snow than from mechanical charging of shattered snow flakes and ice crystals.

Scratch behavior of boron nitride nanotube/boron nitride nanoplatelet hybrid reinforced ZrB2-SiC composites

Spherical instrumented scratch behavior of ZrB2-SiC composites with and without hybrid boron nitride nanotubes (BNNTs) and boron nitride nanoplatelets (BNNPs) was investigated in this research. Typical brittle fracture such as microcracks both in and beyond the residual groove and grain dislodgement was observed in ZrB2-SiC composite, while hybrid BN nanofiller reinforced ZrB2-SiC composite exhibited predominantly ductile deformation. The peculiar three-dimensional hybrid structure in which BNNPs retain their high specific surface area and de-bundled BNNTs extend as tentacles contributes to the improved tolerance to brittle damage. Additionally, easier grain sliding due to BN hybrid nanofillers located at grain boundaries and these BN hybrid nanofillers attached on the scratch surface would provide significant self-lubricating effect to reduce lateral force during scratch and to alleviate contact damage.

Sleep Deprivation Promotes Habitual Control over Goal-Directed Control: Behavioral and Neuroimaging Evidence.

Sleep is one of the most fundamental processes of life, playing an important role in the regulation of brain function. The long-term lack of sleep can cause memory impairments, declines in learning ability, and executive dysfunction. In the present study, we evaluated the effects of sleep deprivation on instrumental learning behavior, particularly goal-directed and habitual actions in humans, and investigated the underlying neural mechanisms. Healthy college students of either gender were enrolled and randomly divided into sleep deprivation group and sleep control group. fMRI data were collected. We found that one night of sleep deprivation led to greater responsiveness to stimuli that were associated with devalued outcomes in the slips-of-action test, indicating a deficit in the formation of goal-directed control and an overreliance on habits. Furthermore, sleep deprivation had no effect on the expression of acquired goal-directed action. The level of goal-directed action after sleep deprivation was positively correlated with baseline working memory capacity. The neuroimaging data indicated that goal-directed learning mainly recruited the ventromedial PFC (vmPFC), the activation of which was less pronounced during goal-directed learning after sleep deprivation. Activation of the vmPFC during goal-directed learning during training was positively correlated with the level of goal-directed action performance. The present study suggests that people rely predominantly on habits at the expense of goal-directed control after sleep deprivation, and this process involves the vmPFC. These results contribute to a better understanding of the effects of sleep loss on decision-making.SIGNIFICANCE STATEMENT Understanding the cognitive consequences of sleep deprivation has become extremely important over the past half century, given the continued decline in sleep duration in industrialized societies. Our results provide novel evidence that goal-directed action may be particularly vulnerable to sleep loss, and the brain mechanism underlying this effect was explored. Elucidation of the effects of sleep deprivation on decision-making will deepen our understanding of the function of sleep, emphasizing the role of sleep in cognitive impairments and mental health.

Autonomic conditioning to monetary and social stimuli and aggression in children.

Poor conditioning to punishment, such as loud tones or electric shock, has been proposed as an important factor involved in the etiology of aggressive and psychopathic behavior. However, it is not known whether the association holds when monetary or social stimulus is used as the unconditioned stimulus, and if aggressive individuals also have impaired conditioning to rewards. In this study, skin conductance responses in a conditioning task involving both monetary/social reward and punishment as unconditioned stimuli were assessed in 340 male and female 8- to 9-year-old children from the community. Children reported their reactive and proactive aggression using the Reactive and Proactive Aggression Questionnaire (RPQ; Raine et al., 2006). Results showed that monetary/social reward and punishment were effective in eliciting physiological classical conditioning in children, and that reduced reward conditioning was associated with high levels of proactive aggression in particular. Findings highlight the importance of distinguishing between reactive and proactive aggression when examining antisocial behavior in children, and suggest that reward-oriented treatment programs may not be effective for children with more proactive, instrumental aggressive behavior.

Density, Viscosity, and Refractive Index of Aqueous CO2-Loaded and -Unloaded Ethylaminoethanol (EAE) Solutions from 293.15 to 323.15 K for Post Combustion CO2 Capture

The physical properties of densities, viscosities, and refractive indices, which are important in kinetics and mass transfer processes were measured for aqueous CO2-loaded and -unloaded (EAE) solutions applied in CO2 absorption in the temperature range from 293.15 to 323.15 K at atmospheric pressure. Due to the limitation of the instrument and corrosive behavior with increasing concentration, the mass fractions (w1) of aqueous EAE solutions selected were: as 0.089, 0.178, 0.267, and 0.356, which correspond to the molar concentrations of 1, 2, 3, and 4 mol·L–1, respectively. The determined density, viscosity and refractive index data for binary EAE+H2O and ternary CO2+EAE+H2O systems were correlated using Weiland et al. model, Redlich–Kister equation, extended Arrhenius equation, and a new proposed empirical function. All the calculated density, viscosity, and refractive index data fitted well with experimental values at all operational conditions.

VCSim3: a VR simulator for cardiovascular interventions

PurposeEffective and safe performance of cardiovascular interventions requires excellent catheter/guidewire manipulation skills. These skills are currently mainly gained through an apprenticeship on real patients, which may not be safe or cost-effective. Computer simulation offers an alternative for core skills training. However, replicating the physical behaviour of real instruments navigated through blood vessels is a challenging task.MethodsWe have developed VCSim3—a virtual reality simulator for cardiovascular interventions. The simulator leverages an inextensible Cosserat rod to model virtual catheters and guidewires. Their mechanical properties were optimized with respect to their real counterparts scanned in a silicone phantom using X-ray CT imaging. The instruments are manipulated via a VSP haptic device. Supporting solutions such as fluoroscopic visualization, contrast flow propagation, cardiac motion, balloon inflation, and stent deployment, enable performing a complete angioplasty procedure.ResultsWe present detailed results of simulation accuracy of the virtual instruments, along with their computational performance. In addition, the results of a preliminary face and content validation study conveyed on a group of 17 interventional radiologists are given.ConclusionsVR simulation of cardiovascular procedure can contribute to surgical training and improve the educational experience without putting patients at risk, raising ethical issues or requiring expensive animal or cadaver facilities. VCSim3 is still a prototype, yet the initial results indicate that it provides promising foundations for further development.

Uncertainty in counting ice nucleating particles with continuous flow diffusion chambers

Abstract. This study investigates the measurement of ice nucleating particle (INP) concentrations and sizing of crystals using continuous flow diffusion chambers (CFDCs). CFDCs have been deployed for decades to measure the formation of INPs under controlled humidity and temperature conditions in laboratory studies and by ambient aerosol populations. These measurements have, in turn, been used to construct parameterizations for use in models by relating the formation of ice crystals to state variables such as temperature and humidity as well as aerosol particle properties such as composition and number. We show here that assumptions of ideal instrument behavior are not supported by measurements made with a commercially available CFDC, the SPectrometer for Ice Nucleation (SPIN), and the instrument on which it is based, the Zurich Ice Nucleation Chamber (ZINC). Non-ideal instrument behavior, which is likely inherent to varying degrees in all CFDCs, is caused by exposure of particles to different humidities and/or temperatures than predicated from instrument theory of operation. This can result in a systematic, and variable, underestimation of reported INP concentrations. We find here variable correction factors from 1.5 to 9.5, consistent with previous literature values. We use a machine learning approach to show that non-ideality is most likely due to small-scale flow features where the aerosols are combined with sheath flows. Machine learning is also used to minimize the uncertainty in measured INP concentrations. We suggest that detailed measurement, on an instrument-by-instrument basis, be performed to characterize this uncertainty.

The Effects of the Monoamine Stabilizer (\u2212)-OSU6162 on Binge-Like Eating and Cue-Controlled Food-Seeking Behavior in Rats

Binge-eating disorder (BED) is characterized by recurring episodes of excessive consumption of palatable food and an increased sensitivity to food cues. Patients with BED display an addiction-like symptomatology and the dopamine system might be a potential treatment target. The clinically safe monoamine stabilizer (−)-OSU6162 (OSU6162) restores dopaminergic dysfunction in long-term alcohol-drinking rats and shows promise as a novel treatment for alcohol use disorder. Here, the effects of OSU6162 on consummatory (binge-like eating) and appetitive (cue-controlled seeking) behavior motivated by chocolate-flavored sucrose pellets were evaluated in non-food-restricted male Lister Hooded rats. OSU6162 significantly reduced binge-like intake of chocolate-flavored sucrose pellets without affecting prior chow intake. Furthermore, OSU6162 significantly reduced the cue-controlled seeking of chocolate-flavored sucrose pellets under a second-order schedule of reinforcement before, but not after, the delivery and ingestion of reward, indicating a selective effect on incentive motivational processes. In contrast, the dopamine D2/D3 receptor antagonist raclopride reduced the seeking of chocolate-flavored sucrose pellets both pre- and post reward ingestion and also reduced responding under simpler schedules of seeking behavior. The D1/5 receptor antagonist SCH23390 had no effect on instrumental behavior under any reinforcement schedule tested. Finally, local administration of OSU6162 into the nucleus accumbens core, but not dorsolateral striatum, selectively reduced cue-controlled sucrose seeking. In conclusion, the present results show that OSU6162 reduces binge-like eating behavior and attenuates the impact of cues on seeking of palatable food. This indicates that OSU6162 might serve as a novel BED medication.

Strong seduction: impulsivity and the impact of contextual cues on instrumental behavior in alcohol dependence

Alcohol-related cues acquire incentive salience through Pavlovian conditioning and then can markedly affect instrumental behavior of alcohol-dependent patients to promote relapse. However, it is unclear whether similar effects occur with alcohol-unrelated cues. We tested 116 early-abstinent alcohol-dependent patients and 91 healthy controls who completed a delay discounting task to assess choice impulsivity, and a Pavlovian-to-instrumental transfer (PIT) paradigm employing both alcohol-unrelated and alcohol-related stimuli. To modify instrumental choice behavior, we tiled the background of the computer screen either with conditioned stimuli (CS) previously generated by pairing abstract pictures with pictures indicating monetary gains or losses, or with pictures displaying alcohol or water beverages. CS paired to money gains and losses affected instrumental choices differently. This PIT effect was significantly more pronounced in patients compared to controls, and the group difference was mainly driven by highly impulsive patients. The PIT effect was particularly strong in trials in which the instrumental stimulus required inhibition of instrumental response behavior and the background CS was associated to monetary gains. Under that condition, patients performed inappropriate approach behavior, contrary to their previously formed behavioral intention. Surprisingly, the effect of alcohol and water pictures as background stimuli resembled that of aversive and appetitive CS, respectively. These findings suggest that positively valenced background CS can provoke dysfunctional instrumental approach behavior in impulsive alcohol-dependent patients. Consequently, in real life they might be easily seduced by environmental cues to engage in actions thwarting their long-term goals. Such behaviors may include, but are not limited to, approaching alcohol.

Striatal GPR88 Modulates Foraging Efficiency.

The striatum is anatomically and behaviorally implicated in behaviors that promote efficient foraging. To investigate this function, we studied instrumental choice behavior in mice lacking GPR88, a striatum-enriched orphan G-protein-coupled receptor that modulates striatal medium spiny neuron excitability. Our results reveal that hungry mice lacking GPR88 (KO mice) were slow to acquire food-reinforced lever press but could lever press similar to controls on a progressive ratio schedule. Both WT and KO mice discriminated between reward and no-reward levers; however, KO mice failed to discriminate based on relative quantity-reward (1 vs 3 food pellets) or effort (3 vs 9 lever presses). We also demonstrate preference for the high-reward (3 pellet) lever was selectively reestablished when GPR88 expression was restored to the striatum. We propose that GPR88 expression within the striatum is integral to efficient action-selection during foraging.SIGNIFICANCE STATEMENT Evolutionary pressure driving energy homeostasis favored detection and comparison of caloric value. In wild and laboratory settings, neural systems involved in energy homeostasis bias foraging to maximize energy efficiency. This is observed when foraging behaviors are guided by superior nutritional density or minimized caloric expenditure. The striatum is anatomically and functionally well placed to perform the sensory and motor integration necessary for efficient action selection during foraging. However, few studies have examined this behavioral phenomenon or elucidated underlying molecular mechanisms. Both humans and mice with nonfunctional GPR88 have been shown to present striatal dysfunctions and impaired learning. We demonstrate that GPR88 expression is necessary to efficiently integrate effort and energy density information guiding instrumental choice.

Neural determinants of human goal-directed vs. habitual action control and their relation to trait motivation

Instrumental learning is mediated by goal-directed and habit systems in the brain. While rodent studies implicate distinct prefrontal/striatal regions in goal-directed and habit learning, neural systems underpinning these two processes in humans remain poorly understood. Here, using a validated discrimination learning task that distinguishes goal-directed learning from habit learning in 72 subjects in fMRI, we investigated the corticostriatal correlates of goal-directed learning and tested whether brain activation during learning is associated with trait motivation and behavioral performance in the post-learning test phase. Participants showed enhanced activation in medial prefrontal and posterior cingulate cortices during goal-directed action selection in the training phase, whereas habitual action selection activated bilateral insula, bilateral dorsal caudate and left precentral gyrus. In addition, early phase of learning was associated with increased activation in the frontoparietal control network and dorsal striatum, whereas default mode regions depicted increased activation in the late phase. Finally, avoidance motivation scores measured by Behavioral Inhibition/Activation System (BIS/BAS) correlated with accuracy during goal-directed learning and showed a nominally significant correlation with activation in dorsomedial prefrontal cortex during goal-directed acquisition of stimuli. These findings reveal the temporal dynamics of instrumental behavior and suggest that avoidance motivation predicts performance and brain activity during goal-directed learning.

9 Neurobiology of addiction

Trevor is Professor of Cognitive Neuroscience, being elected to the Chair of Expt. Psychology (and Head of Department) at the University of Cambridge, from October 2002. He is a Fellow of the British Psychological Society (1990), the Academy of Medical Sciences (2000), and the Royal Society (2005). He received the Distinguished Scientific Contribution Award for 2011 from the American Psychological Association. He has published about 750 full papers, with an H index of about 167. He has co-edited eight books, most recently Translational Neuropsychopharmacology (Springer, 2016). Trevor directs the University of Cambridge ‘Behavioural and Clinical Neuroscience Institute’, the mission of which is to enhance translation from basic to clinical neuroscience. His interest in translation began with his co-invention of the CANTAB computerised neuropsychological battery, which is currently used in over 700 institutes and clinical centres world-wide. He stepped down as President of the British Neuroscience Association in 2011 and was made a CBE in the New Year’s Honours list of the U.K. in 2012. In 2014, he shared the ‘Brain Prize’ of the Grete Lundbeck European Brain Research Foundation, the most valuable in neuroscience, and in 2015 he received the “Lifetime Achievement Award” of the British Association for Psychopharmacology’. Much evidence, based on experimental studies of intravenous drug self-administration in experimental animals and neuroimaging studies in humans now supports the view that drug addiction results in part from aberrant learning mediated by dopamine-dependent processes of the limbic-striatal interface, including the amygdala and nucleus accumbens. The neural systems of this interface and other frontostriatal networks mediate several relevant forms of learning, including Pavlovian conditioning, goal-directed, action-outcome learning, and stimulus-response habit learning (which is not controlled by outcomes or goals). Hypothetically, drug addiction involves an imbalance between instrumental behaviour controlled by outcomes and habitual responding mediated by stimulus-response associations, corresponding hypothetically to a devolution of neurobehavioural control from (i) the prefrontal cortex to the striatum, and (ii) from the ventral to the dorsal striatum (Everitt and Robbins 2016). I will consider the experimental evidence relevant to these predictions from studies of both experimental animals and humans with substance use disorders. I will focus especially on stimulant drugs, but will consider other substance use disorders, as well the latter as part of a ‘impulse-compulsive’ spectrum of mental health disorders. For human drug abuse, it is difficult to unravel predispositions or causal neurobehavioural factors contributing to addiction, from potential neurotoxic effects of the drugs themselves. I will thus describe strategies for determining the aetiological role of these factors, based on evidence from (i) experimental animals, using several techniques and (ii) human drug abusers or vulnerable adolescents, based on functional neuroimaging methods, employing both longitudinal and endophenotype designs. I will conclude that both types of influence contribute to the drive to addiction. Finally, I will consider implications of this evidence for possible new therapeutic approaches to drug addiction, whether pharmacological or behavioural. Reference . Everitt BJ, Robbins TW. Drug addiction: updating actions to habits to compulsions ten years on. annual review of psychology2016;67:23–50.

The impact of traumatic stress on Pavlovian biases.

Disturbances in Pavlovian valuation systems are reported to follow traumatic stress exposure. However, motivated decisions are also guided by instrumental mechanisms, but to date the effect of traumatic stress on these instrumental systems remain poorly investigated. Here, we examine whether a single episode of severe traumatic stress influences flexible instrumental decisions through an impact on a Pavlovian system. Twenty-six survivors of the 2011 Norwegian terror attack and 30 matched control subjects performed an instrumental learning task in which Pavlovian and instrumental associations promoted congruent or conflicting responses. We used reinforcement learning models to infer how traumatic stress affected learning and decision-making. Based on the importance of dorsal anterior cingulate cortex (dACC) for cognitive control, we also investigated if individual concentrations of Glx (=glutamate + glutamine) in dACC predicted the Pavlovian bias of choice. Survivors of traumatic stress expressed a greater Pavlovian interference with instrumental action selection and had significantly lower levels of Glx in the dACC. Across subjects, the degree of Pavlovian interference was negatively associated with dACC Glx concentrations. Experiencing traumatic stress appears to render instrumental decisions less flexible by increasing the susceptibility to Pavlovian influences. An observed association between prefrontal glutamatergic levels and this Pavlovian bias provides novel insight into the neurochemical basis of decision-making, and suggests a mechanism by which traumatic stress can impair flexible instrumental behaviours.

Bias in mean velocities and noise in variances and covariances measured using a multistatic acoustic profiler: the Nortek Vectrino Profiler

This paper compiles the technical characteristics and operating principles of the Nortek Vectrino Profiler and reviews previously reported user experiences. A series of experiments are then presented that investigate instrument behaviour and performance, with a particular focus on variations within the profile. First, controlled tests investigate the sensitivity of acoustic amplitude (and Signal-to-Noise Ratio, SNR) and pulse-to-pulse correlation coefficient, R2, to seeding concentration and cell geometry. Second, a novel methodology that systematically shifts profiling cells through a single absolute vertical position investigates the sensitivity of mean velocities, SNR and noise to: (a) emitted sound intensity and the presence (or absence) of acoustic seeding; and (b) varying flow rates under ideal acoustic seeding conditions. A new solution is derived to quantify the noise affecting the two perpendicular tristatic systems of the Vectrino Profiler and its contribution to components of the Reynolds stress tensor. Results suggest that for the Vectrino Profiler: 1. optimum acoustic seeding concentrations are ~3000 to 6000 mg L−1; 2. mean velocity magnitudes are biased by variable amounts in proximal cells but are consistently underestimated in distal cells; 3. noise varies parabolically with a minimum around the ‘sweet spot’, 50 mm below the transceiver; 4. the receiver beams only intersect at the sweet spot and diverge nearer to and further from the transceiver. This divergence significantly reduces the size of the sampled area away from the sweet spot, reducing data quality; 5. the most reliable velocity data will normally be collected in the region between approximately 43 and 61 mm below the transceiver.

Dynamic Torsional and Cyclic Fracture Behavior of ProFile Rotary Instruments at Continuous or Reciprocating Rotation as Visualized with High-speed Digital Video Imaging

IntroductionThis study examined the dynamic fracture behavior of nickel-titanium rotary instruments in torsional or cyclic loading at continuous or reciprocating rotation by means of high-speed digital video imaging. MethodsThe ProFile instruments (size 30, 0.06 taper; Dentsply Maillefer, Ballaigues, Switzerland) were categorized into 4 groups (n = 7 in each group) as follows: torsional/continuous (TC), torsional/reciprocating (TR), cyclic/continuous (CC), and cyclic/reciprocating (CR). Torsional loading was performed by rotating the instruments by holding the tip with a vise. For cyclic loading, a custom-made device with a 38° curvature was used. Dynamic fracture behavior was observed with a high-speed camera. The time to fracture was recorded, and the fractured surface was examined with scanning electron microscopy. ResultsThe TC group initially exhibited necking of the file followed by the development of an initial crack line. The TR group demonstrated opening and closing of a crack according to its rotation in the cutting and noncutting directions, respectively. The CC group separated without any detectable signs of deformation. In the CR group, initial crack formation was recognized in 5 of 7 samples. The reciprocating rotation exhibited a longer time to fracture in both torsional and cyclic fatigue testing (P < .05). The scanning electron microscopic images showed a severely deformed surface in the TR group. ConclusionsThe dynamic fracture behavior of NiTi rotary instruments, as visualized with high-speed digital video imaging, varied between the different modes of rotation and different fatigue testing. Reciprocating rotation induced a slower crack propagation and conferred higher fatigue resistance than continuous rotation in both torsional and cyclic loads.

Is aggressive behavior in Neurofibromatosis Type 1 due to dysregulated inhibitory control, difficulties in interpreting emotional cues, or both?

Objective: Patients with Neurofibromatosis 1 (NF-1) have poor social functioning, problems with conduct and they may exhibit aggressive behavior. Two types of aggressive behavior exist. Reactive aggression rises in response to perceived threat or frustration and is regulated through inhibitory control and reading emotions on faces and in voices. Instrumental aggression is a means of controlling and dominating others and is regulated through understanding others' emotions. Here, we aimed at assessing aggressive behavior in NF-1 and at understanding whether they are due to difficulties in inhibitory control or/and the perception of emotions. Method: Twenty-six participants with NF-1 (age 5 to 16) and 34 matched controls completed one test assessing inhibitory control and three tests assessing the recognition of isolated facial expressions, the attribution of facial expressions to faceless characters in visually presented scenes depicting social interactions, and the attribution of facial expressions to voices of characters involved in social interactions. The intellectual level was also evaluated. Finally, the parents completed scales assessing reactive and instrumental aggression. Results: As compared to controls, participants with NF-1 had higher scores in both reactive (p < 0.02) and instrumental aggression (p < 0.04). Regression analyses showed that difficulties in identifying isolated faces explained instrumental aggression independently of the group, whilst reactive aggression was explained by difficulties in inhibitory control as a function of the group. Conclusions: Patients with NF-1 present with both reactive and instrumental aggressive behavior and, as expected through the literature on general population, this may contribute toward poor social functioning. However, increased aggressive behavior in NF-1 is due to poor inhibitory control, not to difficulties in reading emotions on faces and in voices, even though deficits of these functions are also present.

Role of Anterior Cingulate Cortex in Instrumental Learning: Blockade of Dopamine D1 Receptors Suppresses Overt but Not Covert Learning.

HIGHLIGHTS Blockade of dopamine D1 receptors in ACC suppressed instrumental learning when overt responding was required.Covert learning through observation was not impaired.After treatment with a dopamine antagonist, instrumental learning recovered but not the rat's pretreatment level of effort tolerance.ACC dopamine is not necessary for acquisition of task-relevant cues during learning, but regulates energy expenditure and effort based decision.Dopamine activity in anterior cingulate cortex (ACC) is essential for various aspects of instrumental behavior, including learning and effort based decision making. To dissociate learning from physical effort, we studied both observational (covert) learning, and trial-and-error (overt) learning. If ACC dopamine activity is required for task acquisition, its blockade should impair both overt and covert learning. If dopamine is not required for task acquisition, but solely for regulating the willingness to expend effort for reward, i.e., effort tolerance, blockade should impair overt learning but spare covert learning. Rats learned to push a lever for food rewards either with or without prior observation of an expert conspecific performing the same task. Before daily testing sessions, the rats received bilateral ACC microinfusions of SCH23390, a dopamine D1 receptor antagonist, or saline-control infusions. We found that dopamine blockade suppressed overt responding selectively, leaving covert task acquisition through observational learning intact. In subsequent testing sessions without dopamine blockade, rats recovered their overt-learning capacity but not their pre-treatment level of effort tolerance. These results suggest that ACC dopamine is not required for the acquisition of conditioned behaviors and that apparent learning impairments could instead reflect a reduced level of willingness to expend effort due to cortical dopamine blockade.

Design, simulation, and characterization of a radial opposed migration ion and aerosol classifier (ROMIAC)

We present the design, simulation, and characterization of the radial opposed migration ion and aerosol classifier (ROMIAC), a compact differential electrical mobility classifier. We evaluate the performance of the ROMIAC using a combination of finite element modeling and experimental validation of two nearly identical instruments using tetra-alkyl ammonium halide mass standards and sodium chloride particles. Mobility and efficiency calibrations were performed over a wide range of particle diameters and flow rates to characterize ROMIAC performance under the range of anticipated operating conditions. The ROMIAC performs as designed, though performance deviates from that predicted using simplistic models of the instrument. The underlying causes of this non-ideal behavior are found through finite element simulations that predict the performance of the ROMIAC with greater accuracy than the simplistic models. It is concluded that analytical performance models based on idealized geometries, flows, and fields should not be relied on to make accurate a priori predictions about instrumental behavior if the actual geometry or fields deviate from the ideal assumptions. However, if such deviations are accurately captured, finite element simulations have the potential to predict instrumental performance. The present prototype of the ROMIAC maintains its resolution over nearly three orders of magnitude in particle mobility, obtaining sub-20 nm particle size distributions in a compact package with relatively low flow rate operation requirements.

Rumination following bereavement: an overview

AbstractThis contribution provides an overview of rumination (i.e., thinking repetitively and recurrently about negative events and/or negative emotions) in adjustment to bereavement. First, we summarise a growing literature on rumination and mental health outcomes of bereavement. Next, we compare two main theories explaining the maladaptive effects of rumination after loss, which hold conflicting implications for clinical practice. The Response Styles Theory (RST) states that rumination is a maladaptive confrontation strategy that perpetuates distress by increasing negative cognitions, impairing problem solving and instrumental behaviour and reducing social support. Conversely, the Rumination as Avoidance Hypothesis (RAH) holds that rumination may serve to avoid painful aspects of the loss, thereby hampering adjustment to bereavement. Crucially, while RST predicts that distraction reduces rumination, RAH predicts that loss exposure is more effective. We review evidence for RST and RAH and their clinical ...

Stepwise regimes in elephant trumpet calls: Similarities with brass instrument behavior

Trumpet calls are very loud voiced signals given by highly aroused elephants, and appear to be produced by a forceful expulsion of air through the trunk. Beyond their characteristic “brassy quality” previously attributed to shockwave formation, some trumpet calls are also characterized by stepwise fundamental frequency increase and decrease. Here we used spectral analysis to investigate the frequency composition of trumpet calls from one Asian and one African elephant. We found that the frequency interval between the steps were consistent with resonances expected in the exceptionally long elephant vocal tract. Such stepwise regimes are commonly observed in brass instruments as self-sustained oscillations transiently align on the bore’s resonance frequencies during arpeggios. We suggest that this production mechanism may constitute a rare example of source-filter interaction (where the filter properties affect the behavior of the source) in the vocal system of a terrestrial mammal. These preliminary observations also emphasize how the generalization of musical acoustic models can provide useful insight into the production of animal vocal signals.