Psychology

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    THE IMPACT OF MILD TRAUMATIC BRAIN INJURY ON TIME-FREQUENCY ERP MEASURES AND NEUROPSYCHOLOGICAL FUNCTIONING: A LONGITUDINAL STUDY OF ACUTELY INJURED SERVICE MEMBERS
    (2020) Watts, Adreanna Massey; Bernat, Edward; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Traumatic Brain Injury (TBI) is the most common injury in recent military conflicts, with nearly 500,000 service members sustaining a TBI since 2000. Mild TBI (mTBI), or concussion, is by far the most common type of TBI and has been associated with long-term cognitive complaints and functional impairment. While clinical assessment of mTBI (i.e., MRI and performance-based cognitive testing) occasionally captures subtle abnormalities in the acute period following mTBI, these measurements lack the sensitivity to assess the time course of cognitive recovery from mTBI. The current study assessed cognitive changes from the acute to chronic period following mTBI using advanced time-frequency event-related potential (ERP) analysis, which isolates rapid regional brain activity and measures the functional communication within and between brain networks in response to varying task stimuli. The validity of these ERP biomarkers was evaluated with correlations between abnormal ERP findings and widely used clinical measures of cognitive functioning (i.e., neuropsychological tests and self-reported cognitive symptoms). Differences between mTBI caused by blast explosion versus impact to the head were also evaluated. A sample of 173 service members, comprising an mTBI group, an orthopedically-injured control group, and a healthy control group, completed ERP, neuropsychological, and self-report assessments within weeks following injury and again six months later. Results suggested that mTBI leads to cognitive changes that persist in the acute to post-acute period following injury (i.e., up to 12 weeks). These cognitive changes were reflected by alterations in ERP time-frequency amplitude and functional connectivity measures, and they remained apparent even when controlling for psychiatric symptoms. ERP differences were also evident between blast-related and impact-related mTBI. Conversely, neuropsychological test performance was not sensitive to mTBI. Abnormal ERP time-frequency measures were related to self-reported cognitive symptoms, suggesting these ERP measures are valid biomarkers of cognitive difficulties following mTBI. Critically, cognitive functioning as assessed by ERP measures returned to a level indistinguishable from controls 7-9 months following mTBI, even though more than a third of mTBI patients continued to report cognitive symptoms. These persistent cognitive complaints were more related to post-injury psychiatric symptoms than to the direct effects of brain injury.
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    Electrophysiology of Social Reward Processing in Schizophrenia
    (2018) Catalano, Lauren; Blanchard, Jack J; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Poor social outcomes have been long observed in schizophrenia. Most studies have identified social cognition as an important contributor to social functioning. Recent research suggests that some people with schizophrenia do not appropriately respond to social rewards, including facial expression of positive affect. The aim of the current study was (1) to use electroencephalogram (EEG) and the event related potential (ERP) technique to examine how people with schizophrenia (SZ) and healthy control (HC) participants anticipate and respond to social (smiles) and nonsocial (money) types of feedback; (2) to examine how deficits in social reward processing are associated with motivation and pleasure deficits and social functioning; and (3) to examine differential contributions of social cognition and social reward processing in understanding functioning. Social and monetary incentive delay tasks were used to characterize reward processing. The stimulus preceding negativity (SPN) was evaluated as an index of reward anticipation, and the reward positivity (RewP) was evaluated as an index of reward sensitivity. Results indicated that HC participants (n = 22) showed significantly more anticipation of reward feedback than neutral feedback, as indexed by the SPN. SZ participants (n = 25) showed similar anticipation regardless of whether there was a potential to win a reward. SZ participants were more sensitive to social rewards than HC participants, as indexed by a larger RewP. We were unable to measure the RewP on the money task; however, exploratory analyses on a P2 component suggested there were no group differences in nonsocial reward sensitivity. Within the SZ group, reduced social reward anticipation was related to greater motivation and pleasure deficits but not social functioning. Social cognition was not significantly related to social functioning or social reward processing in the SZ sample. This is the first study to measure the electrophysiological correlates of social and nonsocial reward processing in schizophrenia. Findings provide preliminary evidence of a generalized anticipatory deficit in schizophrenia that is related to impairments in motivation and pleasure. Reward sensitivity to social rewards appears to be intact. Future experimental design considerations are discussed.
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    EFFECTS OF REWARD CONTEXT ON FEEDBACK PROCESSING AS INDEXED BY TIME-FREQUENCY ANALYSIS
    (2016) Massey, Adreanna; Bernat, Edward; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The role of reward context has been investigated as an important factor in feedback processing. Previous work has demonstrated that the amplitude of the feedback negativity (FN) depends on the value of the outcome relative to the range of possible outcomes in a given context, not the objective value of the outcome. However, some research has shown that the FN does not scale with loss magnitude in loss-only contexts, suggesting that some contexts do not show a pattern of context-dependence. Time-frequency decomposition techniques have proven useful for isolating important activity, and have shown that time-domain ERPs can be better represented as separable processes in delta (0-3 Hz) and theta (3-7 Hz). Thus, the current study seeks to assess whether the role of context in feedback processing is better elucidated using time-frequency analysis. Results revealed that theta was more context-dependent and showed a binary response to best-worst differences in the gain and even contexts. Delta was more context-independent: the best outcomes scaled linearly with reward magnitude and best-worst differences scaled with context valence. Our findings reveal that theta and delta are differentially sensitive to context and that context valence may play a critical role in determining how the brain processes good and bad outcomes.
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    THE NEUROPHYSIOLOGICAL BASIS FOR EMOTIONAL MAINTENANCE AND REDUCED GOAL-DIRECTED BEHAVIOR IN SCHIZOPHRENIA
    (2014) Llerena, Katiah; Blanchard, Jack J; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The current study investigated the neurophysiological underpinnings of emotional maintenance in schizophrenia (SCZ) and whether aberrant neural responses predicted deficits in affective decision making and real-world motivated behavior. Event-related potentials (ERPs) were recorded from 27 SCZ outpatients and 23 healthy controls (CN) during an emotional maintenance task in which participants were presented an initial image for 3 seconds and then required to maintain a mental representation of the intensity that image over a delay period of varying lengths and determine whether the initial image was more or less intense than the second image. The Late Positive Potential (LPP) was used as a neurophysiological marker of emotional maintenance during the delay period. SCZ showed normal in-the-moment emotion experience to positive stimuli; however, SCZ rated negative and neutral pictures as more intense than CN. SCZ also displayed deficits in emotional maintenance accuracy. Furthermore, ERP data indicated reduced LPP amplitude during picture viewing for SCZ compared to CN, and only CN showed persistence of the LPP for positive stimuli into the offset delay period for approximately 1 second and this was significantly associated with behavioral emotional maintenance performance. Behavioral emotional maintenance performance also significantly predicted clinically rated negative symptoms (motivation and pleasure) and poor functional outcome. Thus, impairments in emotional maintenance may offer a promising new theory as to why people with SCZ fail to pursue goal-directed activities.