Using multimodal MRI and real-time fMRI neurofeedback to understand the mechanism of attentional control in people with high trait-anxiety

Abstract

Attentional Control Theory is a framework describing how High Trait Anxiety (HTA) impairs performance during attentional control tasks. In this thesis empirical studies were performed to investigate how HTA affects the neural substrates of attentional control and if real-time functional Magnetic Resonance Imaging neurofeedback (rt-fMRI-nf) could be used to improve attentional control and reduce anxiety in HTA individuals.

First, in a combined fMRI1H-Magnetic Resonance Spectroscopy study, a Stroop task was used to elicit functional activation in Dorsolateral Prefrontal Cortex (DLPFC) and Anterior Cingulate Cortex (ACC). Prefrontal Cortex (PFC) Glutamate (Glu) levels were also measured in the same individuals. HTA participants showed reduced task performance relative to Low Trait Anxiety (LTA) participants. Furthermore, there was a positive association between PFC Glu and DLPFC activation during incongruent trials in LTA participants but not in HTA participants, indicating a possible mechanism for impaired attentional control in HTA individuals.

The second series of studies examined the feasibility of rt-fMRI-nf for enhancing DLPCF–ACC functional connectivity and activity in HTA individuals. Trait anxious participants were assigned to either an experimental group, undergoing veridical rt-fMRI-nf, or a control group, receiving sham feedback. Post-rt-fMRInf, the experimental group (EG) showed reduced anxiety levels and increased DLPFC-ACC functional activity and connectivity relative to the control group (CG). Resting State Functional Connectivity (RSFC) and attentional control performance were also assessed pre- and post-rt-fMRI-nf. Whilst connectivitybased rt-fMRI-nf increased RSFC in the Posterior Cingulate Gyrus, there were no effects of rt-fMRI-nf on offline task performance. 
It was shown that trait anxiety affects the relationship between PFC Glu and DLPFC activation, possibly contributing to ineffective task performance when attentional control is required. Furthermore, DLPFC-ACC functional connectivity-based rt-fMRI-nf, led to reduced anxiety and changes in neural activity that could be interpreted as increased processing efficiency in brain circuitry, important for attentional control. However, there were no measurable improvements in task performance.

Date of Award	5 Dec 2019
Original language	English
Awarding Institution	University of Roehampton
Sponsors	Roehampton VC Scholarship
Supervisor	Paul Allen (Director of Studies), Michael Eysenck (Co-Supervisor) & James Gilleen (Co-Supervisor)