UVM Theses and Dissertations
Format:
Print
Author:
Schaubhut, Geoffrey J.
Dept./Program:
Neuroscience Graduate Program
Year:
2014
Degree:
M.S.
Abstract:
Introduction: lmpulsivity is a term generally used to describe action without regard to future consequences.
Components of this construct include high levels of risk taking, a lack of premeditation, a lack of perseverance, and impulsive actions in response to emotional provocation (urgency). Urgency, also termed emotional impulsivity (Barkley, 2010) has been linked to problematic behaviors (Billieux et al., 2010). Additionally, both impulsivity and emotional dysregulation are associated with internalizing (e.g. anxiety/depressive) and extemalizing (e.g. alcohol use disorder) psychopathology (Boschloo et al., 2013). Females experience mood disorders at higher rates than males (American Psychiatric Association, 2013; Nolen-Hoeksema & Girgus, 1994) and show increased effortful control of impulsive behaviors (Martel & Nigg, 2006; Else-Quest et aI,2006) as well as greater cortical activation during inhibition of responses compared to male counterparts (Garavan et al., 2006). Thus, the relationship between emotion and impulsivity may be particularly relevant to behavioral disturbances (e.g. deliberate self-harm [Hawton, 2000] and eating disorders [Lewinson et al., 2002]) in females. While the neurobiology of impulsivity and emotional responsivity has been well studied, the neurobiological underpinning of the relationship between impulsivity and emotion in females is undetermined. Thus, this study aimed to determine the effect of emotional content during response inhibition on behavioral performance and patterns of brain activity.
Hypothesis: We hypothesized that task-irrelevant emotional content would affect impulsive responding such that positive emotions would facilitate inhibition and negative emotions would interfere with response inhibition. We predicted that patterns of brain activity during response inhibition would be affected by emotional processing. Specifically, that inhibition during emotional stimuli would result in increased activity within the traditional response inhibition network (inferior frontal gyrus, anterior cingulate cortex, orbitofrontal cortex, basal ganglia and parietal lobe), as well as regions processing emotion (amygdala, substantia inominate, and insula).
Methods: Eighteen female subjects, age 18-25, completed an emotional response inhibition task; the faces stop signal (FSST) and a traditional stop signal task (SST), using lexical stimuli, during whole brain functional magnetic resonance image employing blood oxygen level dependent (BOLD) signal detection. The FSST included task-irrelevant emotional facial expressions (happy, calm, and angry) within a primary gender discrimination task. Two subjects were removed due to inadequate task performance using established criteria (Potter & Newhouse, 2008). The behavioral analysis included repeated measures analysis of variance (RM-ANOVA) to assess the impact of emotion on task performance (FSST and SST). Paired sample t-tests were used to compare performance across tasks. In completing the functional analysis beta values created from single-subject general linear modeling (GLM) were progressed to second level analysis to determine group-wide effects. Repeated measure analysis of covariance with cluster size thresholding was used to examine both within task and between task effects for the FSST and SST.
Results & Conclusions: Analysis of task performance found that task-irrelevant emotions impacted response inhibition with faster inhibition during positive compared to both neutral and negative expressions. Differences in go reaction time but not speed of inhibition were seen between the emotional (FSST) and lexical (SST) tasks. There was a significant correlation for speed of inhibition between the SST and positive stimuli on the FSST. This correlation was not seen for negative or neutral stimuli supporting the notion that emotions differentially affect impulsive responding. The within task analysis of BOLD activation determined that response inhibition during the FSST resulted in activation of areas classically described in the response inhibition network. However specific brain structures known to regulate emotions interacted with the response inhibition network during the FSST. Interestingly, the inclusion of task irrelevant emotional content resulted in little effect on functional brain activity during go trials. Taken together, these results indicate that several brain regions, including the cerebellum, insula, and supplementary motor area, may be particularly important to the regulation of impulsive choices during emotionally salient events, particularly those that are neutral or negative. It may be that an individual's sensitivity to emotional content as reflected in laboratory tasks of response inhibition has relevance for psychiatric and substance use disorders that are characterized by dysregulated behavior, particularly in regard to emotionally salient environments.
Components of this construct include high levels of risk taking, a lack of premeditation, a lack of perseverance, and impulsive actions in response to emotional provocation (urgency). Urgency, also termed emotional impulsivity (Barkley, 2010) has been linked to problematic behaviors (Billieux et al., 2010). Additionally, both impulsivity and emotional dysregulation are associated with internalizing (e.g. anxiety/depressive) and extemalizing (e.g. alcohol use disorder) psychopathology (Boschloo et al., 2013). Females experience mood disorders at higher rates than males (American Psychiatric Association, 2013; Nolen-Hoeksema & Girgus, 1994) and show increased effortful control of impulsive behaviors (Martel & Nigg, 2006; Else-Quest et aI,2006) as well as greater cortical activation during inhibition of responses compared to male counterparts (Garavan et al., 2006). Thus, the relationship between emotion and impulsivity may be particularly relevant to behavioral disturbances (e.g. deliberate self-harm [Hawton, 2000] and eating disorders [Lewinson et al., 2002]) in females. While the neurobiology of impulsivity and emotional responsivity has been well studied, the neurobiological underpinning of the relationship between impulsivity and emotion in females is undetermined. Thus, this study aimed to determine the effect of emotional content during response inhibition on behavioral performance and patterns of brain activity.
Hypothesis: We hypothesized that task-irrelevant emotional content would affect impulsive responding such that positive emotions would facilitate inhibition and negative emotions would interfere with response inhibition. We predicted that patterns of brain activity during response inhibition would be affected by emotional processing. Specifically, that inhibition during emotional stimuli would result in increased activity within the traditional response inhibition network (inferior frontal gyrus, anterior cingulate cortex, orbitofrontal cortex, basal ganglia and parietal lobe), as well as regions processing emotion (amygdala, substantia inominate, and insula).
Methods: Eighteen female subjects, age 18-25, completed an emotional response inhibition task; the faces stop signal (FSST) and a traditional stop signal task (SST), using lexical stimuli, during whole brain functional magnetic resonance image employing blood oxygen level dependent (BOLD) signal detection. The FSST included task-irrelevant emotional facial expressions (happy, calm, and angry) within a primary gender discrimination task. Two subjects were removed due to inadequate task performance using established criteria (Potter & Newhouse, 2008). The behavioral analysis included repeated measures analysis of variance (RM-ANOVA) to assess the impact of emotion on task performance (FSST and SST). Paired sample t-tests were used to compare performance across tasks. In completing the functional analysis beta values created from single-subject general linear modeling (GLM) were progressed to second level analysis to determine group-wide effects. Repeated measure analysis of covariance with cluster size thresholding was used to examine both within task and between task effects for the FSST and SST.
Results & Conclusions: Analysis of task performance found that task-irrelevant emotions impacted response inhibition with faster inhibition during positive compared to both neutral and negative expressions. Differences in go reaction time but not speed of inhibition were seen between the emotional (FSST) and lexical (SST) tasks. There was a significant correlation for speed of inhibition between the SST and positive stimuli on the FSST. This correlation was not seen for negative or neutral stimuli supporting the notion that emotions differentially affect impulsive responding. The within task analysis of BOLD activation determined that response inhibition during the FSST resulted in activation of areas classically described in the response inhibition network. However specific brain structures known to regulate emotions interacted with the response inhibition network during the FSST. Interestingly, the inclusion of task irrelevant emotional content resulted in little effect on functional brain activity during go trials. Taken together, these results indicate that several brain regions, including the cerebellum, insula, and supplementary motor area, may be particularly important to the regulation of impulsive choices during emotionally salient events, particularly those that are neutral or negative. It may be that an individual's sensitivity to emotional content as reflected in laboratory tasks of response inhibition has relevance for psychiatric and substance use disorders that are characterized by dysregulated behavior, particularly in regard to emotionally salient environments.