WWW.DISSERTATION.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Dissertations, online materials
 
<< HOME
CONTACTS



Pages:     | 1 |   ...   | 9 | 10 || 12 | 13 |   ...   | 15 |

«by Amy Lynn Byrd, Ph.D. B.S. in Psychology, College of Charleston, 2006 M.S. in Clinical Psychology, University of Pittsburgh, 2010 Submitted to the ...»

-- [ Page 11 ] --

A primary objective of this dissertation was to characterize the BOLD response to the receipt of reward and punishment among subgroups of boys with early-onset CP. It was hypothesized that youth with CP, regardless of their level of CU traits (or psychopathic features), would exhibit hyper-reactivity to reward in the VS relative to HC. Contrary to hypotheses, boys with CP and low CU traits exhibited reduced reactivity to big reward in the DS (i.e., caudate) relative to both HC and youth with CP and CU, who evidenced increased activation to reward in this same region. Moreover, youth with CP and low levels of CU traits exhibited a similar pattern of hypoactivation to reward in the amygdala and mPFC relative to HC and these differences were not evident when subgroups were characterized by the presence of psychopathic features. Taken together, results provide some initial evidence for potential differences in the mechanisms underlying reward processing in subgroups of youth with and without CU traits.

Abnormalities in punishment processing were expected in all ROIs examined and were hypothesized to be most pronounced in a subgroup of CP youth with elevated levels of CU traits (and psychopathic features). Results provided partial support of hypotheses and, consistent with the behavioral literature, were indicative of a primary deficit within this domain. Results were most reliable and robust with regard to responsivity to punishment in the amygdala. As predicted, boys with CP demonstrated reduced reactivity to punishment in this region relative to HC who evidenced significant activation. Additionally, CP youth evidenced reduced activation

–  –  –

analyses and in the opposite direction of hypotheses. Also contrary to prediction, there was no evidence to support that punishment insensitivity was most pronounced in CP youth with CU traits or psychopathic features. Moreover, no consistent differences emerged within regulatory regions (e.g., ACC, OFC) suggesting abnormalities during initial encoding are specific to subcortical regions. Lastly, differences in neural response were specific to big reward and big punishment and this may be a reflection of the task design rather that the magnitude of the monetary gain/loss. Specifically, small reward and punishment may be less salient given the possibility of larger reward/punishment. Results are discussed within the context of the broader literature below.

The second aim of the current dissertation was to evaluate the extent to which individual differences in reward and/or punishment processing were associated with responsiveness to intervention. This objective was notably exploratory in nature and sought to test the notion that abnormalities in reward and/or punishment processing may influence the impact of a multimodal intervention that focuses on behavioral principles associated with reward and punishment contingencies. Contrary to hypotheses, reactivity to reward and punishment among CP youth was unrelated to level of CP following treatment and abnormalities in neural processing failed to moderate the effectiveness of SNAP intervention. Though small sample sizes and reduced power may have contributed to null effects, results provide support for the success of this multi-modal, empirically supported intervention among boys with early-onset CP and aberrant reward/punishment processing. These findings are discussed in greater detail below.

–  –  –

Group differences in reward processing emerged within the striatum, providing some evidence for abnormalities in response to reward among youth with CP. However, contrary to prediction, differences were specific to the DS, namely the caudate, and were unrelated to VS reactivity.

This suggests group variation in reward processing may be less related to the emotional experiences of reward (Cardinal, et al., 2002) and instead specific to responsivity to uncertain reward and the acquisition of reward-action associations (Delgado, Miller, Inati, & Phelps, 2005;

Elliott, Newman, Longe, & William Deakin, 2004). Moreover, group differences emerged in the unexpected direction and between subgroups of CP youth, specific to the presence or absence of CU traits. Boys with CP and CU demonstrated increased activation in the caudate, no different than that of HC, but significantly greater than boys with CP and low levels of CU traits. Results also provide additional evidence for hypo-activity to reward among boys with CP and low levels of CU, who demonstrated reduced activation to reward in the amygdala and mPFC relative to HC. These deficits may have important implications for reward-based learning (Cardinal, et al., 2002; Fareri, et al., 2008; Matthys, Vanderschuren, & Schutter, 2012a) and suggest that CP youth with low levels of CU traits could experience difficulty in this regard.

At the same time, it is important to note that the aforementioned group differences were reduced to non-significance after controlling for potential confounds, with some suggestion that deficits in responsivity to reward were uniquely associated with clinically significant internalizing problems. This is particularly interesting given emerging literature that documents associations between internalizing problems, namely depression, and reduced responsivity throughout reward-related circuitry (Forbes, et al., 2006; Forbes & Dahl, 2005; Forbes, Shaw, & Dahl, 2007). In light of research documenting high rates of comorbidity between CP and

–  –  –





to disentangle whether potential deficits in reward processing represent a shared or unique etiology. As such, the utilization of alternative comparison groups (e.g., youth with internalizing problems only) may help to elucidate these findings.

It is also important to highlight that the hypo-activity to reward seen among CP youth with low CU stands in direct contrast to youth with CP and CU, who demonstrated more normative responsivity to reward in the caudate. Moreover, in continuous analyses CU traits were uniquely associated with increased activation in the caudate after controlling for CP, though this fell just below the cluster threshold. Additionally, whole-brain analyses found youth with CP and CU to exhibit hyper-activation to reward within the cingulate and postcentral gyrus. While these analyses were notably exploratory in nature and identify regions outside of the rewardrelated circuitry that could be less functionally significant, this pattern of over-activation in this subgroup may warrant further inquiry. Along these lines, recent neuroimaging work reports similar inconsistencies among samples of CP youth with regard to hyper- versus hypo-activation within reward related circuitry (e.g., Bjork, et al., 2010; Rubia, et al., 2009), which may be related to a failure to examine CU traits. Thus, while there continues to be debate about whether CP is driven by over- versus under-reactivity to reward (Quay, 1993; Zuckerman, 1996), it may be important to consider potential differences in the mechanisms underlying reward function between subgroups of CP youth with and without CU traits and/or with and without co-occurring internalizing problems.

–  –  –

Amygdala Group differences were expected be most pronounced and diffuse with regard to punishment processing. Results provide confirmation for reduced reactivity to punishment among boys with early-onset CP. Both group and continuous analyses support hypotheses and consistently found boys with CP to demonstrate reduced activation in the amygdala following the receipt of punishment. Moreover, these findings remained significant after accounting for important confounds (i.e., income, IQ, etc.). While other neuroimaging studies in this area have provided some support for amygdala dysfunction in response to punishment (e.g., Finger, et al., 2011), these studies have utilized relatively complex tasks that incorporate multiple phases of learning (i.e., encoding, acquisition, extinction) and often examine the neural response to removal of reward as opposed to the introduction of punishment (Bjork, et al., 2010; Rubia, et al., 2009). To our knowledge, this dissertation represents the first neuroimaging study to examine basic responsivity to the receipt of punishment in the form of monetary loss among CP youth in late childhood. Current findings build upon behavioral work in this area which consistently finds children with CP have lower reactivity to inherently aversive stimuli or positive punishment (e.g., lound tones; Herpertz, et al., 2001; van Goozen, et al., 2004), by demonstrating a similar insensitivity to negative punishment (i.e., loss of money). This reduced sensitivity to punishment has been well-documented across childhood and adolescence, with recent work suggesting that these deficits are present as early as 3 years of age and serve to predict criminal offending in adulthood (Gao, Raine, Venables, Dawson, & Mednick, 2010). Taken together, this provides evidence that reduced emotional arousal to both positive (i.e., introduction of something aversive) and negative (i.e., removal of something pleasurable) punishment may hinder the

–  –  –

ultimately increasing the likelihood of the development and persistence of CP (Kochanska, 1994).

In line with findings from the current dissertation, the amygdala has been a recent focus of the neuroimaging literature within this population, with studies consistently demonstrating links between amygdala dysfunction and heightened levels of CP in youth. This is consistent with theory proposing deficient processing within this region, particularly among youth with elevated CP and CU (Blair, 2007; Kiehl, 2006). For example, studies have shown structural differences in gray matter volume of the amygdala among youth with CP (De Brito et al. 2009;

Huebner et al. 2008; Sterzer et al. 2007) and adults with a history of early-onset CP (Pardini et al. 2013). Other work in this area has focused on amygdala reactivity during emotion processing tasks, specifically reactivity to emotional faces, and find youth with CP and high levels of CU traits or psychopathic features to evidence reduced amygdala reactivity relative to controls (for review see Hyde, Shaw, & Hariri, 2013; Jones, Laurens, Herba, Barker, & Viding, 2009; Marsh, et al., 2008). However, contrary to prediction, the current dissertation found no differences between subgroups of CP youth, whether defined by the presence of CU traits or psychopathic features. Noteworthy, the majority of previous research in this area compares youth with CP and CU traits (or psychopathic features) to HC, making it impossible to discern whether significant group differences are driven by the presence of CP or CU. The current dissertation is one of the only investigations to examine potential differences in neural processing between subgroups of CP youth (see also Hyde, 2012 for studies examining emotion processing among subgroups;

Viding, et al., 2012 ). Moreover, CP subgroups within the current study were indistinguishable in terms of demographic and other clinically relevant variables (e.g., internalizing problems,

–  –  –

of the rigorous study design, failure to detect significant within group differences is indicative of similar punishment processing among these subgroups of CP youth and suggests that previous findings may be attributable to the presence of CP as opposed to CU or psychopathic features.

Striatum In addition to robust associations between CP and reduced activation in the amygdala, the current dissertation also provided some evidence for reduced reactivity to punishment within the striatum, though this varied by location and subgroup. Specifically, CPCU- evidenced reduced activation in the caudate relative to HC (no differences with CPCU+) while CP PSY+ exhibited decreased activation in the putamen compared to HC (no differences with CP PSY-).

Inconsistency of results may reflect the lack of complete overlap between CU and PSY group classifications and certainly warrant caution with regard to interpretation. However, it is also important to note that the direction of these findings are contrary to previous work in the area (Finger, et al., 2008; Gatzke-Kopp, et al., 2009) and emerging theory (Glenn & Yang, 2012).

Specifically, past research has documented increased activation within the DS following punishment and this has been interpreted as an inability to appropriately process the absence of reward. In other words, CP youth may be processing punishment as if it was (or should be) reward due to ineffective error monitoring or a failure to process contingency change. This is thought to increase their propensity to continuously engage in perseverative, reward-focused action and may impair the ability to flexibly respond to the environment (Newman & Lorenz, 2002). Results in the current dissertation may reflect the unpredictable nature of the task design (i.e., no learning or contingency change) and thus, findings can only speak to an inherently

–  –  –

the presence of competing reward and punishment.



Pages:     | 1 |   ...   | 9 | 10 || 12 | 13 |   ...   | 15 |


Similar works:

«ISSN(Online) : 2319-8753 ISSN (Print) : 2347-6710 International Journal of Innovative Research in Science, Engineering and Technology (An ISO 3297: 2007 Certified Organization) Vol. 5, Issue 8, August 2016 Design approach of Eye Tracking and Mind Operated Motorized System Susmita Das1, Sayan Kumar Swar2, Shrisom Laha2, Subhankar Mahindar2, Suchetana Halder3, Koushik Hati2, Sandipan Deb2 Assistant Professor, Department of Electronics and Instrumentation Engineering, Narula Institute of...»

«Fools Die Mario Puzo Book I Chapter 1 “Listen to me. I will tell you the truth about a man’s life. I will tell you the truth about his love for women. That he never hates them. Already you think I’m on the wrong track. Stay with me. Really—I’m a master of magic. “Do you believe a man can truly love a woman and constantly betray her? Never mind physically, but betray her in his mind, in the very ‘poetry of his soul.’ Well, it’s not easy, but men do it all the time. “Do you...»

«Intentional Binding and the Sense of Agency: A review James W. Moore1,2 & Sukhvinder S. Obhi3,4 1. Department of Psychology, Goldsmiths, University of London, London, UK 2. Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Cambridge, UK 3. Centre for Cognitive Neuroscience & Department of Psychology, Wilfrid Laurier University, Waterloo, Ontario, Canada 4. Institute of Cognitive Neuroscience, University College London, London, U.K. Correspondence: sobhi@wlu.ca PrePrint...»

«The Experience of Humour in Asperger s syndrome Susan Teresa Ruggeri A Thesis submitted in fulfilment of the requirements of the University Of Wolverhampton for the degree of Doctor of Counselling Psychology. This work or any part thereof has not previously been presented in any form to the University or any other body whether for the purpose of assessment, publication or for any other purpose (unless otherwise specified). Save for any express acknowledgements, references, and/or bibliographies...»

«Your Benefit Guide State Vision Plan For Active Employees and Retirees Blue Cross Blue Shield of Michigan is a nonprofit corporation and independent licensee of the Blue Cross and Blue Shield Association. Welcome Welcome to your State Vision Plan, administered by Blue Cross Blue Shield of Michigan (BCBSM) under the direction of the Michigan Civil Service Commission (MCSC). The MCSC is responsible for implementing your vision benefits and future changes in benefits. BCBSM will provide certain...»

«Begin Reading Table of Contents Copyright Page In accordance with the U.S. Copyright Act of 1976, the scanning, uploading, and electronic sharing of any part of this book without the permission of the publisher constitute unlawful piracy and theft of the author’s intellectual property. If you would like to use material from the book (other than for review purposes), prior written permission must be obtained by contacting the publisher at permissions@hbgusa.com. Thank you for your support of...»

«ORGANIZATION BENEFITS – THE PANACEA FOR ALL THAT AILS YOU? A DYADIC, DUAL-EARNER INVESTIGATION OF ORGANIZATION-OFFERED BENEFITS AND THEIR EFFECT ON INDIVIDUALS AND THEIR PARTNERS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Psychology by Suzanne M. Booth-LeDoux B.S., McNeese State University, 2008 M.A., Louisiana...»

«Some Ways that Maps and Diagrams Communicate Barbara Tversky Department of Psychology, Stanford University Stanford, CA 94305-2130 bt@psych.stanford.edu Abstract. Since ancient times, people have devised cognitive artifacts to extend memory and ease information processing. Among them are graphics, which use elements and the spatial relations among them to represent worlds that are actually or metaphorically spatial. Maps schematize the real world in that they are two-dimensional, they omit...»

«THE JOURNAL OF NEUROLOGY AND PSYCHOPATHOLOGY Vol. XVII. APRIL, 1937 No. 68 Oriuuatnal 1apers AN ENQUIRY INTO THE CAUSES OF MESCAL VISIONS BY C. R. MARSHALL, TUNBRIDGE WELLS INTRODUCTION MESCAL hallucinations have recently been investigated in the hope that their elucidation might help to unravel other hallucinatory phenomena. Zucker 1 administered mescaline to patients with hallucinations. From the protocols given many of the effects obtained (coloured lights, tapestry patterns, visions of...»

«VARIATION OF FEEDING REGIMES: EFFECTS ON GIANT PANDA (AILUROPODA MELANOLEUCA) BEHAVIOR A Thesis Presented to The Academic Faculty By Estelle A. Sandhaus In Partial Fulfillment Of the Requirements for the Degree Master of Science in Psychology Georgia Institute of Technology September, 2004 Variation of Feeding Regimes: Effects on Giant Panda (Ailuropoda melanoleuca) Behavior Approved by: Dr. Terry L. Maple, Advisor School of Psychology Georgia Institute of Technology Dr. Mollie A. Bloomsmith...»

«The Real Thing 1. The Taste Test There’s something very special about a school fair. It’s the excitement of the weeks building up to it, and all the work that the kids do in the classroom, painting posters and making signs. It’s the colour and the bustle of the day itself, and how it always seems to be sunny, and the fact that on school fair day all the rules about what you’re allowed to eat, and not to eat, go straight out the window, and you’re allowed to stuff yourself with toffee...»

«Chinese Military Modernization and Asian Security Michael Swaine August 1998 1 2 Chinese Military Modernization and Asian Security* Michael Swaine I’ll speak on the question of Chinese military defense modernization and its implications for the Asian security environment. I’ll try to keep my remarks at a level where we can talk about broader issues and concepts, and the implications of all this for regional evolution in the security environment, U.S. security interests, U.S.-Japan...»





 
<<  HOME   |    CONTACTS
2016 www.dissertation.xlibx.info - Dissertations, online materials

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.