Date on Senior Honors Thesis

10-2025

Document Type

Senior Honors Thesis

Degree Name

B.S.

Cooperating University

University of Louisville

Department

Psychological and Brain Sciences

Degree Program

College of Arts and Sciences

Committee Chair

Brendan Depue

Committee Member

Brendan Depue

Committee Member

Andrew Lynn

Committee Member

Mark Running

Author's Keywords

Neuroticism; Anterior Cingulate Cortex; Neuroimaging; Psychopathology; Diffusion-Weighted-Imaging; DWI; Structural Connectivity

Abstract

Neuroticism is a trait which has been shown to significantly predict psychopathology. Investigating its neurobiological underpinnings may uncover a brain-based relationship that allows clinicians to conceptualize a shared predispositional factor across multiple psychopathologies, implicating treatment protocols. Inter-connectivity network and structural variation has been shown to be implicated in neuroticism, more specifically the frontoparietal network, default mode network, salience networks, and limbic networks. These networks tackle executive, salience, and emotional information, respectively. The anterior cingulate cortex (ACC) is a brain region nested between and functionally related to various networks stated above that are implicated in neuroticism. As such, it was hypothesized that the ACC would show altered connectivity patterns to various nodes of the networks stated above: greater connection to the medial prefrontal cortex (mPFC), less connection to the lateral prefrontal cortex (LPFC), and greater connection to limbic regions such as the amygdala, hippocampus, and thalamus. In a final sample of 190 participants (median age range 25-30), white matter connectivity was estimated using MRtrix3 while cortical and subcortical regions consisting of the FPN, DMN, SN, and limbic networks were taken from FreeSurfer. Spearman’s ⍴ correlations of the strength of white matter connectivity from the ACC to each ROI revealed no significant differences in connectivity to neuroticism scores. This implicates the complexity of personality dynamics and implies that alterations in network dynamics more reliably produce brain-based changes seen in these factors, and that structural alterations may not be implicated as brain-based changes that are associated with neuroticism or other personality traits.

Lay Summary

The personality trait of neuroticism, which is the psychological tendency to have frequent, intense negative emotions as well as a bias toward negative emotion, aligns closely with the features of many mental disorders. Neuroticism has been found to relate to mental disorders, in that it may serve as an aspect of brain structure and function which underlies multiple disorders. The anterior cingulate cortex (ACC) is a brain region near other regions of the brain which process various cognitive functions that are disrupted in neuroticism such as emotion generation and logistical reasoning. Thus, it was hypothesized that it would have altered connections between brain regions involved in emotion (limbic regions) and brain regions involved in emotional appraisal or cognitive control (executive/frontal regions). The connectivity of the ACC between these frontal and limbic regions was examined using MRI methods that measure the white matter connectivity across regions of the brain. Results showed no association between altered connectivity between the ACC and its frontal/limbic targets with neuroticism. This illustrates the fact that other means of investigating the brain may more likely be able to uncover complex processes such as neuroticism.

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