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FUNCTIONAL BRAIN CONNECTIVITY ASSOCIATED WITH REPETITIVE BEHAVIOR IN AUTISM SPECTRUM DISORDER
Title
FUNCTIONAL BRAIN CONNECTIVITY ASSOCIATED WITH REPETITIVE BEHAVIOR IN AUTISM SPECTRUM DISORDER.
Creator
MacDowell, Kenton Hayes, Sheremata, Summer L., Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description
The high prevalence of autism spectrum disorder (ASD) results in large costs to individuals, families, and society. Among diagnosed individuals, restrictive and repetitive behaviors (RRBs) correlate with functional impairments substantially impacting wellbeing but remain less studied than social and communication deficits. Brain resting-state functional connectivity (fc) measures intrinsic, potentially RRB-associated neural dynamics. Here, whole-brain (WB), and iterated seed-based (SB)fc...
Show moreThe high prevalence of autism spectrum disorder (ASD) results in large costs to individuals, families, and society. Among diagnosed individuals, restrictive and repetitive behaviors (RRBs) correlate with functional impairments substantially impacting wellbeing but remain less studied than social and communication deficits. Brain resting-state functional connectivity (fc) measures intrinsic, potentially RRB-associated neural dynamics. Here, whole-brain (WB), and iterated seed-based (SB)fc guided by the preceding WBfc and a priori hypotheses was performed. Combined results were used to model a brain network beginning with qualitative assessment of its potential functional association with RRBs. Once rigorously defined, the network was used to inform construction of a dynamical systems model of brain activity hypothesized to correlate with RRB severity. Qualitative model behavior tracked expectations of real cortical activity in RRB presentation. Model numerical output was found to correlate with behavioral measures of RRBs to a significantly greater degree than the underlying brain connectivity values themselves did. Some summary measures of model output were also found to correlate significantly, though near threshold, with severity measures in the other two ASD core deficit domains, and particularly, far more extensively than should be expected given the underlying brain connectivity values themselves were apparently effectively wholly uncorrelated with the measures. Significant findings are: (1) dynamical modeling of brain activity can identify significant correlations with symptom manifestation that fc alone cannot; (2) dynamical modeling of brain activity could potentially increase understanding of ASD’s extensive heterogeneity across symptom domains; (3) extensive overlap between the constructed network and known RRB-implicated brain divisions was identified, with cerebellum, increasingly implicated in distributed neocortical functional differences in RRBs in humans and animal models, centrally connected to multiple such divisions; (4) further overlap is found via striatal circuitry, implicated in multiple RRB-like behaviors previously, and forming at least 1/3 of the functional basis for the network’s hypothetical relationship with RRBs; (5) ASD-associated angular gyrus, PFC, ACC overlap was found. This successful tandem application of fc, dynamical modeling, and neurocognitive network theory illustrates the need for broad theoretical approaches in illuminating ASD heterogeneity and the neurocognitive underpinnings of specific ASD presentations.
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Date Issued
2021
PURL
http://purl.flvc.org/fau/fd/FA00013792
Subject Headings
Autism spectrum disorders, Behavior, Neurocommunication
Format
Document (PDF)
EEG SIGNALS REPRESENT UPDATED MEMORY REPRESENTATIONS IN VISUAL WORKING MEMORY
Title
EEG SIGNALS REPRESENT UPDATED MEMORY REPRESENTATIONS IN VISUAL WORKING MEMORY.
Creator
Shin, Young Seon, Sheremata, Summer L., Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description
Visual working memory (VWM) is a core cognitive system that supports our ability to maintain and manipulate visual information temporarily when sensory information is no longer present in the environment. VWM and mental rotation, a form of mental imagery, require the ability to generate internal images in the absence of stimuli. Both cognitive processes share visual buffer and are associated with representing and manipulating visual information, however, little is known about the intersection...
Show moreVisual working memory (VWM) is a core cognitive system that supports our ability to maintain and manipulate visual information temporarily when sensory information is no longer present in the environment. VWM and mental rotation, a form of mental imagery, require the ability to generate internal images in the absence of stimuli. Both cognitive processes share visual buffer and are associated with representing and manipulating visual information, however, little is known about the intersection between VWM and mental rotation. In the current work, mental rotation was adopted to study updated mnemonic contents in VWM. In this dissertation, I asked whether the brain mechanisms that support VWM and mental rotation overlap. Participants were asked to remember the orientation of grating or to remember and manipulate, that is mentally rotate, the orientation of grating. Behavioral results showed that mental rotation induced lower fidelity representations of orientation. This confirmed that additional usage in visual buffer to manipulate the visual representation provoked by mental rotation involved negative influence in memory fidelity. In the second study, EEG recording was conducted while participants performed the same task. Visual representations were reconstructed from brain oscillations using the inverted encoding model (IEM). It was found that orientation information from the reconstruction was represented in the amplitude of alpha oscillations (8 – 12 Hz) for both maintained and updated mnemonic contents. Together, this work provides evidence that memory manipulation driven by mental rotation has a decisive effect on the fidelity of visual representations in VWM. Additionally this dissertation demonstrates that the updated memory representations as well as the maintained memory representations are carried in EEG oscillations.
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Date Issued
2022
PURL
http://purl.flvc.org/fau/fd/FA00013890
Subject Headings
Short-term memory, Visual Perception, Electroencephalography, Mental rotation
Format
Document (PDF)