Browsing by Subject "Startle"

Now showing 1 - 3 of 3
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    Interview assessment of boldness: construct validity and empirical links to psychopathy and fearlessness.
    (2009-08) Hall, Jason Robert
    The triarchic model of psychopathy (Patrick, Fowles, & Krueger, in press) conceptualizes this intriguing disorder in terms of three distinct elemental phenotypes: disinhibition, reflecting tendencies toward deficient behavioral control and externalizing psychopathology; meanness, reflecting deliberate cruelty and agentic exploitation of others; and boldness, reflecting resilience to life stress, calmness in the face of threat, and social dominance. The predominant instrument for assessing criminal psychopathy, Hare's (1991, 2003) Psychopathy Checklist-Revised (PCL-R), appears to tap the disinhibition and meanness facets of psychopathy directly and substantially, but captures boldness only indirectly and to a modest degree. Given its reliance on antisocially deviant indicators, the PCL-R is also ill-suited to investigation of non-criminal psychopathy in community settings. Thus, the primary aim of the present study was to evaluate the construct validity and neurobiological correlates of a newly-developed interview measure of the phenotypic boldness construct. Relationships between the Boldness Interview (BI) and multi-modal measures of psychopathy, externalizing psychopathology, and personality traits with theoretical or empirical links to the boldness construct were investigated in a sample of incarcerated adult males. The present study also investigated relationships between the BI measure and emotional modulation of the startle blink reflex - a well-validated physiological measure of fear reactivity that has previously been linked to the interpersonal-affective features of PCL-R psychopathy - in a picture-viewing paradigm. Results strongly supported the construct validity of the BI. Consistent with theory and prediction, BI total scores were: substantially and positively related to the PCL-R Interpersonal facet, the fearless dominance factor of the self-report Psychopathic Personality Inventory (Lilienfeld & Andrews, 1996), and self-reported narcissism, thrill-seeking, and dominance; negatively related to self-report measures of harm avoidance, trait anxiety, fear, and internalizing symptoms; and largely unrelated to externalizing psychopathology. Total scores on the BI were also related to reduced startle amplitude during aversive pictures in the picture-viewing paradigm. These results are discussed in terms of their implications for the assessment and conceptualization of psychopathy (particularly non-criminal psychopathy) as well as the neurobiological underpinnings of the disorder.
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    Neural mechanisms of anxiety during opiate withdrawal:role of the ventral tegmental area and extended amygdala.
    (2011-07) Radke, Anna Kay
    Exposure to addictive drugs alters neural circuits involved in reward and motivation, executive control, habit formation, learning and memory, and negative affect, and all except the last are known to depend on changes in the mesolimbic dopamine system. Negative affective symptoms of withdrawal are common to all drugs of abuse and negatively reinforce drug taking behavior. Using potentiation of the acoustic startle reflex as a measure of anxiety during withdrawal from acute morphine exposure, the experiments detailed in this thesis tested the hypothesis that µ-opioid receptor-mediated activation of VTA dopaminergic neurons is responsible for triggering negative emotional symptoms of withdrawal via recruitment of the extended amygdala. These experiments demonstrate the emergence of a negative affective state that occurs during withdrawal from direct infusion of morphine into the ventral tegmental area (VTA), the origin of the mesolimbic dopamine system. Potentiation of startle during withdrawal from systemic morphine exposure requires a decrease in ì-opioid receptor stimulation in the VTA and can be relieved by systemic or intra-nucleus accumbens administration of a dopamine receptor agonist. Investigation of mechanisms downstream of dopaminergic signaling found a role for type 2 corticotropin-releasing factor receptors following the very first, but not subsequent, opiate exposures. Together these results suggest that transient activation of the VTA mesolimbic dopamine system triggers the expression of anxiety during opiate withdrawal, possibly via direct recruitment of the extended amygdala. This conclusion provides unique insight into the neural mechanisms responsible for negative reinforcement of drug taking during the earliest stages of dependence.
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    Psychophysiological and fMRI investigations of tobacco cue reactivity.
    (2010-06) Engelmann, Jeffrey Michael
    Development of new smoking-cessation therapies may be facilitated by identifying the neural basis of smoking-related emotional responses. In this dissertation, the affective consequences of cigarette smoking and abstinence were modeled in rats and humans using a potentiated-startle paradigm. In rats, repeated daily nicotine injections resulted in increased startle amplitude 2 h after nicotine exposure, which is consistent with the emergence of an anxiety-like withdrawal episode. In humans, startle responses to tobacco, pleasant, neutral, and unpleasant cues were measured in nonsmokers, nonabstinent smokers, and smokers who were 24 h into a 48 h abstinence period. Startle amplitude was potentiated during unpleasant cues in nonsmokers and abstinent smokers, but not in nonabstinent smokers, which suggests that smoking a cigarette reduced anxiety. Event-related brain potentials also suggested that abstinent smokers were more emotionally reactive than nonsmokers and nonabstinent smokers to both tobacco cues and unpleasant cues. An additional, functional magnetic resonance imaging study found that that two brain regions, the dorsal striatum and the anterior cingulate cortex, were involved in the expression of abstinent smokers' emotional responses to tobacco and unpleasant cues. These results suggest negative affect may be important in maintaining cigarette smoking and that the potentiated startle paradigm is an ideal model for preclinical and clinical studies of smoking-related emotional responses.