Phantom controllers: Misspecified models create the false appearance of adaptive control during value-based choice

Decision scientists have grown increasingly interested in how people adaptively control their decision making. Researchers have demonstrated that parameters governing the accumulation of evidence towards a choice, such as the decision threshold, are shaped by information available prior to or in parallel with one's evaluation of an option set (e.g., recent outcomes or choice conflict). A recent account has taken a bold leap forward in this approach, suggesting that adjustments in decision parameters can be motivated by the value of the options under consideration. This motivated control account predicts that when faced with difficult choices (similarly valued options) under time pressure, people will adaptively lower their decision threshold to ensure that they make a choice in time. This account was supported by drift diffusion modeling of a deadlined choice task, demonstrating that decision thresholds decrease for difficult relative to easy choices. Here, we reanalyze the data from this experiment, and show that evidence for this novel account does not hold up to further scrutiny. Using a more systematic and comprehensive modeling approach, we show that this previously observed threshold adjustment disappears (or even reverses) under a more complete model of the data. Importantly, we further show how this and other apparent evidence for motivated control arises as an artifact of model (mis)specification, where one model's putatively controlled decision process (e.g., value-driven threshold adjustments) can mimic another model's stimulus-driven decision processes (e.g., accumulator competition or collapsing bounds). Collectively, this work reveals crucial insights and constraints in the pursuit of understanding how control guides decision-making, and when it doesn't.

Filling the gaps: Cognitive control as a critical lens for understanding mechanisms of value-based decision-making

While often seeming to investigate rather different problems, research into value-based decision making and cognitive control have historically offered parallel insights into how people select thoughts and actions. While the former studies how people weigh costs and benefits to make a decision, the latter studies how they adjust information processing to achieve their goals. Recent work has highlighted ways in which decision-making research can inform our understanding of cognitive control. Here, we provide the complementary perspective: how cognitive control research has informed understanding of decision-making. We highlight three particular areas of research where this critical interchange has occurred: (1) how different types of goals shape the evaluation of choice options, (2) how people use control to adjust the ways they make their decisions, and (3) how people monitor decisions to inform adjustments to control at multiple levels and timescales. We show how adopting this alternate viewpoint offers new insight into the determinants of both decisions and control; provides alternative interpretations for common neuroeconomic findings; and generates fruitful directions for future research.

Expectations of reward and efficacy guide cognitive control allocation

The amount of mental effort we invest in a task is influenced by the reward we can expect if we perform that task well. However, some of the rewards that have the greatest potential for driving these efforts are partly determined by factors beyond one's control. In such cases, effort has more limited efficacy for obtaining rewards. According to the Expected Value of Control theory, people integrate information about the expected reward and efficacy of task performance to determine the expected value of control, and then adjust their control allocation (i.e., mental effort) accordingly. Here we test this theory's key behavioral and neural predictions. We show that participants invest more cognitive control when this control is more rewarding and more efficacious, and that these incentive components separately modulate EEG signatures of incentive evaluation and proactive control allocation. Our findings support the prediction that people combine expectations of reward and efficacy to determine how much effort to invest.

Simultaneous Detection of Seven Drugs of Abuse by the TriageTM Panel for Drugs of Abuse

This novel, competitive immunoassay simultaneously detects seven drugs of abuse in urine. A urine sample is placed in contact with lyophilized reagents, the reaction mixture is allowed to come to equilibrium (10 min), and then the whole mixture is applied to a solid phase that contains various immobilized antibodies in discrete drug-class-specific zones. After a washing step, the operator visually examines each zone for the presence of a red bar. The method incorporates present threshold concentrations that are independent for each drug. In the absence of drug or in the presence of drug in quantities less than the threshold concentration, no colored bar is visible. Samples containing drug(s) at or above the threshold concentration cause a red bar to appear for the appropriate drug(s). Positive and negative procedural control zones are incorporated into each determination. The performance of the assay methodology matches that of instrumented immunoassay systems.

Effects of Synchronized Cardiac Assist Device on Cardiac Energetics

A novel physiological cardiac assist device (PCAD), the LEV RAM assist device, which is synchronized with the failing heart ejection, was developed to improve the failing heart systolic and diastolic functions and cardiac energetics. The PCAD uses a single short cannula, which is inserted into the beating left ventricle (LV) by means of a specially designed device. Blood is ejected from the PCAD into the LV after the opening of the aortic valve and augments the cardiac stroke work. The same amount of blood is withdrawn from the LV into the PCAD, through the same cannula, during the diastole. The study aims to test the effects of the PCAD on cardiac energetics and coronary blood flow. Adult normal sheep were anesthetized and the heart was exposed by left thoracotomy. Pressures transducers (Millar Instruments, Inc., Houston, TX) were inserted into the LV and aorta. LV volume was measured by sonocrystals (Sonometrics Corp., London, Ontario, Canada) and impedance catheter (CD Lycom, Argonstrat 116 Zoetermeer, 2718 SP The Netherlands). Flowmeters (transonic) measured the cardiac output (CO) and the coronary arteries (left anterior descending (LAD) and circumflex) flows. A thin cannula was inserted into the coronary sinus and the oxygen content of the LV and the coronary sinus were determined (AVOXimeter-1000). Pressure-volume loops, myocardial energetics, and coronary flow were measured. The displaced PCAD volume was 11 mL. Four different levels of assist were studied by changing the frequency of the assist: (1) assist beat after three successive regular beats [1:4], (2) assist every third beat [1:3], (3) alternate assist and normal beat [1:2], and (4) continuous assist [1:1]. Cardiac output (CO) and stroke volume (SV) increased proportionally with increasing frequency of assist. Systolic mechanical efficiency of the PCAD was above 90%. Simultaneously, the PCAD decreased the end-diastolic volume (EDV; diastolic unloading). The PCAD increased coronary flow and decreased cardiac arterial-venous O(2) difference. We conclude that the PCAD efficiently augments CO and stroke work, decreases preload, and decreases the coronary arterial-venous O(2) difference; all these may expedite cardiac reverse remodeling, and promote recovery of function and eventual easy explanation of the device.

Augmentation of Dilated Failing Left Ventricular Stroke Work by a Physiological Cardiac Assist Device

A novel physiological cardiac assist device (PCAD), otherwise known as the LEVRAM assist device, which is synchronized with the heartbeat, was developed to assist the left ventricle (LV) in chronic heart failure (CHF). The PCAD utilizes a single cannula, which is inserted in less than 15 s through the apex of the beating LV by means of a specially designed device. Blood is withdrawn from the LV into the PCAD in diastole and is injected back to the LV, through the same cannula, during the systolic ejection phase, thereby augmenting stroke volume (SV) and stroke work (SW). CHF with dilated LV was induced in sheep by successive intracoronary injections of 100-microm beads. The sheep (92.2 +/- 25.9 kg, n = 5) developed stable CHF with increased LV end-diastolic diameter (69.4 +/- 3.3 mm) and end-diastolic volume (LVEDV = 239 +/- 32 mL), with severely reduced ejection fraction (23.8 +/- 7.6%), as well as mild-to-moderate mitral regurgitation. The sheep were anesthetized, and the heart was exposed by left thoracotomy. Pressure was measured in the LV and aorta (Millar). The SV was measured by flow meters and the LV volume by sonocrystals. Assist was provided every 10 regular beats, and the assisted beats were compared with the preceding unassisted beats, at the same LVEDV. The PCAD displaced 13.6 +/- 3.4 mL, less than 8% of LVEDV. Added SW was calculated from the assisted and control pressure-volume loops. The efficiency, defined as an increase in SW divided by the mechanical work of the PCAD, was 85.4 +/- 16.9%. We conclude that the PCAD, working with a small displaced blood volume in synchrony with the heartbeat, efficiently augments the SW of the dilated failing LV. The PCAD is suggested for use as a permanent implantable device in CHF.

Gradient field switching as a source for artifacts in MR imaging of metallic stents

Metallic implants, such as stents, have long been a concern in magnetic resonance imaging (MRI). In addition to safety issues, they are commonly associated with image artifacts. The mechanisms of radiofrequency- (RF) and susceptibility-induced artifacts have been thoroughly investigated. However, gradient-switching-induced artifacts have not been analyzed. In this study it was demonstrated that gradient switching may be a source of artifacts in metallic stent MR imaging. These artifacts differ from those caused by the RF pulse. A theoretical explanation is provided as well.

In vivo extracellular recording of sympathetic ganglion activity in a chronic animal model

Surgery of the sympathetic system is performed for a variety of indications, hyperhidrosis being a major one. Despite excellent results, sympathectomy for hyperhidrosis bears a number of sequels, some of which may be devastating. Several surgical methods, empirically advocated to alleviate these problems, have only limited success. Chronic in vivo recording of the electrical activity from sympathetic ganglia may assist in understanding and clarifying complex problems of sympathetic surgery; however, no suitable method has been reported. An electrode device developed by our group was implanted on the stellate ganglion, in a chronic animal model (dog). The signals obtained were amplified, filtered, and transmitted via an A/D interface to be acquired and saved on a computer, using special software which we developed. Our method enabled the separate recording of neuroelectrical signals, ECG, and respiration waves. An additional software program, also developed by our group, was used to analyze the data. This chronic animal model allows investigation of surgical and pharmacological manipulations of the sympathetic system.

Modulation of functional properties of galectin-3 by monoclonal antibodies binding to the non-lectin domains

Galectin-3 is a member of a newly defined family of animal lectins, which is composed of three domains: a small amino-terminal domain, a domain containing repeating elements, and a carboxyl-terminal domain containing the carbohydrate-recognition site. Various functions have been described or proposed for this lectin, and it appears that galectin-3 has diverse roles. Murine monoclonal antibodies (MAbs) have been generated from mice hyperimmunized with recombinant human galectin-3 or galectin-3C (the carboxyl-terminal domain), and seven MAbs have been characterized in detail. All MAbs generated against the intact galectin-3 recognize the amino-terminal region of the molecule, as demonstrated by ELISA and immunoblotting using recombinant galectin-3C and galectin-3NR, which contains the amino-terminal domain and all the repeating elements. Their epitopes were all found to be within the first 45 amino acids of galectin-3, as determined by using galectin-3 mutants with a truncated amino-terminal region. However, these MAbs were found to profoundly modulate the lectin activities of galectin-3. The MAb B2C10 inhibited (i) the binding of 125I-labeled galectin-3 to IgE coated on microtiter plates; (ii) the galectin-3's hemagglutination activity; and (iii) galectin-3-induced superoxide production by human neutrophils. Other MAbs, especially A3A12, caused marked potentiation of these activities. The results support our model that the lectin function of galectin-3 is influenced by protein homodimerization resulting from self-association of the amino-terminal region of the molecule. The potentiating activities of some MAbs are probably due to facilitation of dimerization galectin-3, and the inhibitory activity of MAb B2C10 is probably the result of its disruption of the self-association process.

Preparation and characterization of polyclonal and monoclonal antibodies specific for covalently linked DNA/RNA cross sections

Covalently linked cross sections refer to structures that mimic hydrogen-bonded purine-pyrimidine, purine-purine, and pyrimidine-pyrimidine duplexes. Cross sections dA [symbol:see text] U and A [symbol: see text] dT, which have been synthesized chemically, have molecular dimensions similar to purine-pyrimidine base pairs in a double helix. We propose that antibodies to such covalent cross sections might facilitate the study of the pathogenesis of specific diseases or of biochemical processes in which base pair involvement is suspected and/or demonstrated. We have made polyclonal antibodies against "A:U" and "A:T" cross sections by immunizing rabbits with dA [symbol: see text] U and A [symbol: see text] dT, each conjugated to keyhole limpet hemocyanin (KLH). The antibodies were found to be highly specific for the cross sections and to cross react minimally to single nucleosides. Hybridomas secreting monoclonal antibodies to "A:T" were then generated from spleen cells of mice immunized with A [symbol: see text] dT conjugated to KLH. The MAbs produced were also found to be highly specific for "A:T" among various nucleosides. In fact, the binding of most of the monoclonal antibodies to "A:T" was only partially inhibited by high concentrations of adenosine or thymidine. All monoclonal antibodies to "A:T" cross react, but with lower affinity, to "A:U." Selected MAbs showed greater inhibition of binding to "A:T"-BSA by A + T than by A or T alone.

Simultaneous detection of seven drugs of abuse by the Triage panel for drugs of abuse

This novel, competitive immunoassay simultaneously detects seven drugs of abuse in urine. A urine sample is placed in contact with lyophilized reagents, the reaction mixture is allowed to come to equilibrium (10 min), and then the whole mixture is applied to a solid phase that contains various immobilized antibodies in discrete drug-class-specific zones. After a washing step, the operator visually examines each zone for the presence of a red bar. The method incorporates present threshold concentrations that are independent for each drug. In the absence of drug or in the presence of drug in quantities less than the threshold concentration, no colored bar is visible. Samples containing drug(s) at or above the threshold concentration cause a red bar to appear for the appropriate drug(s). Positive and negative procedural control zones are incorporated into each determination. The performance of the assay methodology matches that of instrumented immunoassay systems.

A patient of German descent with (delta beta)0-thalassemia carrying the Sicilian type deletion of the delta and beta globin genes

A deletion-type (delta beta)0-thalassemia with elevated production of fetal hemoglobin (Hb F) is described. The patient, homozygous for the disease, presented a clinical picture of beta-thalassemia intermedia. DNA analysis demonstrated that the deletion removed about 13 kb from the beta-globin cluster, including part of delta and the complete beta gene. The deletion appears to be identical to the previously described Sicilian deletion. Its presence in the homozygous state in a patient from Central Europe suggests that the deleted chromosome may be rather prevalent in that area.