Neuroscience
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Neuroscience research of Undergraduate Honors Students in the Psychological Sciences at Vanderbilt University.
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Item Intravenous arachnoid granulation volume changes in patients with Parkinson disease(Vanderbilt University, 2024) Leguizamon, MelanieWe apply novel deep learning algorithms to T2-weighted MRI to test hypotheses regarding arachnoid granulation (AG) hypertrophy in patients with Parkinson’s disease (PD). Using this method, we identify AG protruding into the superior sagittal sinus, which may serve as a site of CSF egress. Results from statistical analyses suggest a significant increase in total AG volume in patients with PD compared to age-matched healthy controls, potentially indicating reduced neurofluid clearance efficiency. Further correlational analyses revealed revealed significant relationships between total AG volume and MiniBEST, as well as significant relationships for AG number with MiniBEST and SDMT. Actigraphy data indicate a negative relationship between total AG volume and sleep efficiency and a positive relationship between AG volume and number of awakenings, but no significant relationships with other actigraphy sleep measures. Finally, sleep efficiency was strongly negatively correlated with AG number before correcting for false discovery rate. Chronic sleep disturbance may contribute to AG hypertrophy as a compensatory mechanism for a dysregulated glymphatic system in patients with PD to clear waste.Item Structural Brain Differences in Individuals with Bipolar Disorder: A Developmental Perspective(Vanderbilt University, 2023-03) Milewski, AmyWhile the existence of bipolar disorder in early adolescence is becoming more widely accepted, the degree of manifestation in childhood is still unclear. This thesis summarizes findings on neurostructural correlates of adult bipolar disorder compared to more limited research on pediatric bipolar disorder. Then we examined the relationship between mania symptoms and brain structure in a large sample of children. We analyzed data from 10,699 9-to-10-year-old children from the Adolescent Brain Cognitive Development (ABCD) Study. We employed structural equation modeling to examine the associations between subsyndromal mania symptoms and cortical grey matter volume and thickness in 68 regions. After correction for multiple comparisons and controlling for age, sex, race/ethnicity, and scanner model, we found that mania was associated with smaller brain volumes in 54 cortical regions (pfdr-values ≤ .048). However, none of these effects survived sensitivity analyses that accounted for socioeconomic status, medication use, in-scanner motion, or total intracranial volume (pfdr-values ≥ .299). There were no significant associations between mania and cortical thickness in any region (pfdr-values ≥ .249). Prior studies have identified structural differences in individuals with bipolar disorder, which is supported by the current study’s results in children. However, these results do not survive when controlling for additional covariates, possibly due to the young age of the current sample. Future studies should associate subsyndromal mania with cortical volume and thickness longitudinally to refine our understanding of the emergence of structural changes during the prodromal stage, which could be leveraged for improved identification and intervention.Item Investigating Brain Networks in Anxious-Misery and Fear Symptom Dimensions(Vanderbilt University, 2022-03) Pines, JuliaAnxiety and depressive symptoms can be dissociated into anxious-misery and fear components; however, little is known about how these two symptom dimensions differ in terms of brain network properties. Thus, the purpose of this study was to compare the local efficiency of the default mode network (DMN) and frontoparietal network (FPN) in anxious-misery and fear symptom dimensions, with examination of six additional networks and small-worldness as exploratory analyses. To do this, we used data from children ages 9-10 years old from the Adolescent Brain Cognitive Development (ABCD) Study database. Our primary measure of interest was local efficiency, which measures the efficiency of information exchange between nodes of a network when one node is removed. We hypothesized that the DMN would exhibit increased local efficiency and the FPN would show decreased local efficiency in anxious-misery symptoms, and both networks would have lower local efficiency in fear symptoms. We found no significant associations between local efficiency and anxious-misery and fear dimensions or between small-world omega and the dimensions. However, we found a significant positive association between anxious-misery symptoms and local efficiency in the FPN and a significant negative association between fear symptoms and local efficiency in the FPN at uncorrected levels. These results suggest the need for further study of local efficiency in the FPN in an older population and the use of other network metrics in anxious-misery and fear symptom dimensions.Item Exploring Predictors of Affective State during d-Amphetamine Intake(Vanderbilt University, 2019-04-08) Kundzicz, Paul; Zald, David; Smith, ChristopherItem Analysis of Structural Network Topology in Depression using Graph Theory(Vanderbilt University, 2019) Ganesh, SwathiNeuroimaging studies have suggested a difference in structural brain connectivity in depression. Recently, structural brain connectivity and psychopathology have been studied using graph theory analysis, which provides metrics on properties of brain organization. While there have been some studies applying this analytic technique to study depression, these have largely been done using categorical rather than dimensional approaches to psychopathology. This study applied both a traditional categorical approach and a dimensional approach to examine the relation between commonly used graph theory measures and depression. The dimensional analysis included 439 subjects and the categorical approach included 357 subjects with depressive symptoms and 82 subjects without any diagnoses. Anatomical co-variance matrices were constructed using 9 morphometric features and matrices were analyzed to produce the following metrics: normalized clustering coefficient, normalized path length, small-world parameter, normalized global efficiency, and normalized local efficiency. The categorical approach utilized an ANCOVA and the dimensional approach utilized multiple regressions. The categorical analysis did not suggest a significant difference between the “depressed” and “healthy” group with regards to any of the graph theory metrics. In the dimensional analysis a significant positive relation was identified between depressive symptom counts and both normalized local efficiency and normalized clustering coefficient. This shows some concordance with previous studies, and suggests that global features of white matter microstructure may be relevant for depression when examined dimensionally. Future studies using other types of neuroimaging data and applying graph theory techniques may yield additional insight into which graph theory metrics are most relevant for depression.Item Impact of Constraint-Induced Movement Therapy on Brain Function in Children with Cerebral Palsy(Vanderbilt University, 2012-03-29) Aschner, Amir; Maitre, Nathalie L.; Key, Alexandra F.Few studies have examined the effects of Constraint-Induced Movement Therapy (CIMT) in children or its effects beyond sensory-motor domains. Evidence from adult populations suggests that CIMT is linked with cortical restructuring and could have effects on speech, language deficits, and sensory-perceptual processes, domains typically affected by cerebral palsy (CP). Using a five-day camp model, CIMT effects were tested on children age 5-12 with CP using behavioral measures and two event-related potential (ERP) paradigms –speech sound perception and picture-word matching. Data were collected at baseline, immediately after treatment, and 6 months after the camp. We found that paretic limb function improved after CIMT, and ERP waveform patters changed significantly to reflect faster processing and improved organization. These changes persisted at 6 months follow-up.Item Neurocognitive Effects of Treatment of Pediatric Acute Lymphocytic Leukemia: A Neuroimaging Analysis(Vanderbilt University, 2008-04-04) Livesay, KateAcute Lymphocytic Leukemia (ALL) is the most prevalent form of cancer diagnosed in children. The current survival rate is approximately 85% and has been rising over the last two decades. The standard treatment regimen involves intrathecal chemotherapy in addition to corticosteroid drugs. Intrathecal chemotherapy has been shown to cause neurocognitive effects in executive function and IQ. The current study investigates differences in brain activation patterns that could account for the differences in neurocognitive function observed between ALL survivors and healthy controls. In this study, neurocognitive function of ALL survivors was assessed using a test battery that consisted of the Wechsler Intelligence Test for Children-Fourth Edition (WISC-IV) and the Delis-Kaplan Executive Function System (D-KEFS). ALL survivors showed significant deficits on these tests compared to matched, healthy controls. Survivors demonstrating the poorest performance on this battery participated in the neuroimaging component of the study in which brain activation during an inhibitory control task, the Simon task, was measured using functional magnetic resonance imaging (fMRI). ALL survivors demonstrated a compensatory mechanism of cortical recruitment during the Simon task, while performing worse than their matched, healthy controls. There was a significant difference in activation between survivors and healthy controls in the anterior cingulate cortex (BA 24), as predicted, although no differences were found between groups in the prefrontal cortex.Item Effect of striatal and extrastriatal D2-receptor BP on memory and symptoms of schizotypal personality disorder(Vanderbilt University, 2007-04) Patterson, Katherine A.The integrity of particular dopaminergic projections via the striato-thalamiccortical feedback loop potentially influences specialized aspects of cognition and psychopathology. Research has identified a role for striatal D2 receptors in the cognitive impairments and psychopathological symptoms associated with disorders of the schizophrenia spectrum. Recent developments in PET neuroimaging methods currently permit visualization of D2/D3 receptors in extrastriatal regions. This study evaluated potential correlations between the regional D2/D3 receptor BP in striatal and extrastriatal areas and psychopathological symptoms and memory performance. Significant correlations were observed between particular regions of D2/D3 receptor BP and both verbal and visual memory sub-scales of the Wechsler Memory Scale-III.Item Effect of binocular rivalry suppression on contrast change detection(Vanderbilt University, 2008-04) Hubert-Wallander, Bjorn; Blake, RandolphIn their 2004 study, Watanabe et al. measure the detectability of contrast increment probes during rivalry dominance and suppression by plotting threshold versus contrast (TvC)functions, finding significant elevation of detection thresholds during suppression. But what about contrast decrements, a probe that actually makes the target image harder to see? Here I review the literature on binocular rivalry and probe studies and measure the effect of two new probe types on detection thresholds. Results show that contrast decrement probes produce a very different pattern of detection thresholds than their increment counterparts. Extrapolating from these results, I also theorize on the effect of suppression on the underlying contrast response function (CRF).