Publications by authors named "Dennis Ta"

Spinal cord injury (SCI) is a widespread, life-altering injury leading to impairment of sensorimotor function that, while once thought to be permanent, is now being treated with the hope of one day being able to restore function. Surface electromyography (EMG) presents an opportunity to examine and promote human engagement at the neuromuscular level, enabling new protocols for intervention that could be combined with robotic rehabilitation, particularly when robot motion or force sensing may be unusable due to the user's impairment. In this paper, a myoelectric control interface to an exoskeleton for the elbow and wrist was evaluated on a population of ten able-bodied participants and four individuals with cervical-level SCI.

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Rehabilitation exoskeletons may make use of myoelectric control to restore in patients with significant motor impairment following a spinal cord injury (SCI) a sense of volitional control over their limb - a crucial component for recovery of movement. Little investigation has been done into the feasibility of using surface electromyography (sEMG) as an exoskeleton control interface for SCI patients, whose impairment manifests in a highly variable way across the patient population. We have demonstrated that by using only a small subset of features extracted from eight bipolar electrodes recording on the upper arm and forearm muscles, we can achieve high predictive accuracy for the intended direction of motion.

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Decision makers face difficult choices when tasked with identifying and implementing appropriate mechanisms for protecting the elderly and other vulnerable adults from abuse. A pilot project involving fingerprint-based criminal history background checks for personal care workers in Michigan has supplied an opportunity to examine one such mechanism. In conjunction with the pilot project, we have conducted a stakeholder analysis with the aim of informing decision makers about stakeholder perceptions of standard policy criteria like effectiveness, efficiency, and equity.

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The decision to intentionally withhold truthful information, or deception, is a key component of moral development and may be a precursor to more serious anti-social tendencies. Two factors, executive function and temperamental fear are each thought to influence childhood deception. Few studies, however, have explored deception in relation to both of these factors simultaneously.

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Interest in the use of mobile technology to deliver mental health services has grown in light of the economic and practical barriers to treatment. Yet, research on alternative delivery strategies that are more affordable, accessible, and engaging is in its infancy. Attention bias modification training (ABMT), has potential to reduce treatment barriers as a mobile intervention for stress and anxiety, but the degree to which ABMT can be embedded in a mobile gaming format and its potential for transfer of benefits is unknown.

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Threat bias, or exaggerated selective attention to threat, is considered a key neurocognitive factor in the etiology and maintenance of pediatric anxiety disorders. However, upon closer examination of the literature, there is greater heterogeneity in threat-related attentional biases than typically acknowledged. This is likely impacting progress that can be made in terms of interventions focused on modifying this bias and reducing anxiety, namely attention bias modification training.

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The ability to use cognitive emotion regulation strategies such as reappraisal may be a core component of emotional competence across development, but due to methodological challenges in measuring such strategies, they are rarely studied in young children. One neurophysiological measure, the late positive potential (LPP), has been examined in response to reappraisal as a potential neurosignature for emotion regulatory capacity in adults. The association between the LPP and emotion regulatory capacity in children is unknown.

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The late positive potential (LPP), which is reduced following the use of reappraisal, is a potential neurosignature for emotion regulation capacity. This sensitivity of the LPP to reappraisal is rarely studied in children. We tested whether, in 26 typically developing seven- to nine-year-olds, LPP amplitudes were reduced following reappraisal and whether this effect varied with age and anxiety.

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Processes through which parental ideology is transmitted to children-especially at a young age prior to the formation of political beliefs-remain poorly understood. Given recent evidence that political ideology is associated with neural responses to cognitive conflict in adults, we tested the exploratory hypothesis that children's neurocognitive responses to conflict may also differ depending on their parents' ideology. We assessed relations between parental political ideology and children's neurocognitive responses to conflict, as measured by the N2 component of the event-related potential.

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The Hv1 channel and voltage-sensitive phosphatases share with voltage-gated sodium, potassium, and calcium channels the ability to detect changes in membrane potential through voltage-sensing domains (VSDs). However, they lack the pore domain typical of these other channels. NaV, KV, and CaV proteins can be found in neurons and muscles, where they play important roles in electrical excitability.

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Negative affectivity (NA) is a broad construct that has been associated with the development of psychopathologies, such as anxiety, and with exaggerated attention to threatening stimuli. EEG asymmetry reflects biological individual differences in emotional reactivity that may underlie the association between NA and attention to threat. The present study included a sample of 31 five-seven year olds (M age in months=74.

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Enhanced threat processing has been associated with elevated anxiety in adults, but less is known about how threat processing influences the developmental trajectory of anxiety in children. We used the N170 to measure threat (angry faces) processing in relation to child anxiety over a 2-year period. Participants were 27 typically developing 5-to-7-year-olds (13 females).

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Although inhibited behavior problems are prevalent in childhood, relatively little is known about the intrinsic and extrinsic factors that predict a child's ability to regulate inhibited behavior during fear- and anxiety-provoking tasks. Inhibited behavior may be linked to both disruptions in avoidance-related processing of aversive stimuli and in approach-related processing of appetitive stimuli, but previous findings are contradictory and rarely integrate consideration of the socialization context. The current exploratory study used a novel combination of neurophysiological and observation-based methods to examine whether a neurophysiological measure sensitive to approach- and avoidance-oriented emotional processing, the late positive potential (LPP), interacted with observed approach- (promotion) and avoidance- (prevention) oriented parenting practices to predict children's observed inhibited behavior.

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Voltage-gated sodium, potassium, and calcium channels are made of a pore domain (PD) controlled by four voltage-sensing domains (VSDs). The PD contains the ion permeation pathway and the activation gate located on the intracellular side of the membrane. A large number of small molecules are known to inhibit the PD by acting as open channel blockers.

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The late positive potential (LPP) reflects increased attention to emotional versus neutral stimuli in adults. To date, very few studies have examined the LPP in children, and whether it can be used to measure patterns of emotional processing that are related to dispositional mood characteristics, such as temperamental fear and anxiety. To examine this question,39 typically developing 5–7 year olds (M age in months = 75.

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Cognitive emotion regulation strategies, such as reappraising the emotional meaning of events, are linked to positive adjustment and are disrupted in individuals showing emotional distress, like anxiety. The late positive potential (LPP) is sensitive to reappraisal: LPP amplitudes are reduced when unpleasant pictures are reappraised in a positive light, suggesting regulation of negative emotion. However, only one study has examined reappraisal in children using the LPP.

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Anxiety is characterized by exaggerated attention to threat. Several studies suggest that this threat bias plays a causal role in the development and maintenance of anxiety disorders. Furthermore, although the threat bias can be reduced in anxious individuals and induced in non-anxious individual, the attentional mechanisms underlying these changes remain unclear.

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Dual competition framework (DCF) posits that low-level threat may facilitate behavioral performance by influencing executive control functions. Anxiety is thought to strengthen this effect by enhancing threat's affective significance. To test these ideas directly, we examined the effects of low-level threat and experimentally induced anxiety on one executive control function, the efficiency of response inhibition.

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The scaffold protein IscU and molecular chaperones HscA and HscB play central roles in biological assembly of iron-sulfur clusters and maturation of iron-sulfur proteins. However, the structure of IscU-FeS complexes and the molecular mechanism whereby the chaperones facilitate cluster transfer to acceptor proteins are not well understood. We have prepared amino acid substitution mutants of Escherichia coli IscU in which potential ligands to the FeS cluster (Cys-37, Cys-63, His-105, and Cys-106) were individually replaced with alanine.

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Whether task-irrelevant emotional stimuli facilitate or disrupt attention performance may depend on a range of factors, such as emotion type, task difficulty, and stimulus duration. Few studies, however, have systematically examined the influence of these factors on attention performance. Sixty-three adults, scoring within a normative range for mood and anxiety symptoms, completed either an easy or difficult version of an attention task measuring three aspects of attention performance: alerting, orienting, and executive attention.

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Despite recent evidence that neural correlates of error monitoring such as the error-related negativity (ERN) and error positivity (Pe) are visible in children sooner than previously thought, little is known about these components early in life. Error-monitoring components can be noninvasively recorded from a very early age and have been proposed as biological markers of risk for psychopathology. Therefore, the current study represents an attempt to examine the presence of these components in a sample of very young children and explore their associations with affect and attentional control.

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Background: General iron-sulfur cluster biosynthesis proceeds through assembly of a transient cluster on IscU followed by its transfer to a recipient apo-protein. The efficiency of the second step is increased by the presence of HscA and HscB, but the reason behind this is poorly understood. To shed light on the function of HscB, we began a study on the nature of its interaction with IscU.

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Frontal EEG activity is thought to reflect affective dispositions, but may also reflect the emotional demands of a specific context combined with the capability to regulate emotions in that context. The present study examined this hypothesis by testing whether frontal EEG activity during mood inductions versus a resting baseline predicted emotion regulation. EEG was recorded while participants (N=66, 40 females) received a fearful, sad, or neutral mood induction.

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Neuroscientific research on emotion regulation suggests that the interplay between emotion and cognition may be fundamental to the ability to adaptively regulate emotions. Although emotion and cognition have historically been considered to be in opposition, more recent research suggests that they are also integrated, coordinated, and complementary. In this article, I review studies showing that scalp-recorded event related potentials (ERPs) reflecting emotion-cognition integration can be used as clinically meaningful indices of emotion regulation in children and adults, and have the potential to serve as biomarkers for emotion regulation and risk for specific affective disorders.

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