Neuroplasticity in an Extended Amygdala Network as a Target Mechanism for Attention Bias Modification Outcome
Anxiety disorders are one of the most common psychological disorders. Underlying anxiety is an increased attentional bias to threat, which has been identified as a causal contributor in the development of anxiety. Given this causal relationship, attention bias modification was introduced as a treatment option where anxiety is reduced by training individuals to direct their attention away from threat and thereby decreasing anxiety. Over a decade of research using this approach, called attention bias modification (ABM), suggests that overall the approach is effective in reducing anxiety. Although ABM appears to be a very promising treatment option for anxiety, there are several factors limiting the effectiveness of ABM. These include the recognition of individual-level needs and a known underlying mechanism of action by which ABM is effective. Neuroimaging evidence suggests that attentional bias to visual threat is associated with a network of brain regions including the amygdala, anterior cingulate cortex, and visual cortex. In human participants, experience-dependent neuroplasticity is visible in voxel-based morphometry based measures of gray matter volume following training. Recently, voxel-based morphometry measures of gray matter volume have been linked to dendritic spine density-a known cellular mechanism for learning-related neuroplasticity. Thus, voxel-based morphometry measures are ideally suited to measure learning-related neuroplasticity following attention bias modification. In this proposal participants' level of attentional bias, anxiety, and gray matter volume will be measured before and after completing six weeks of attention bias modification training (N = 50) or attention control training (N= 50). The proposal aims to (1) establish that pre-treatment bias predicts variability in gray matter volume in the extended amygdala and anterior cingulate cortex, (2) assess the extent to which reduced extended amygdala and anterior cingulate cortex gray matter volume following ABM underlies reductions in attentional bias and anxiety, and (3) Establish pre-treatment bias as a predictor of successful ABM as measured by reduced bias, reduced anxiety, and reduced gray matter volume in the extended amygdala and anterior cingulate cortex. Consistent with the objectives of the AREA grant and NIMH's focus on identifying and validating new targets for treatment development that underlie disease mechanisms, the current proposal plans to involve students at a rural primarily undergraduate university in a research project aimed at establishing neuroplasticity in the extended amygdala and anterior cingulate cortex as a target mechanism for ABM training outcome, which could be used to objectively track training-related outcomes in anxiety treatment.
|Condition or Disease||Intervention/Treatment||Phase|
Arms and Interventions
|Experimental: Attention Bias Modification
Behavioral: Attention Bias Modification
Attention bias modification (ABM) sessions will consist of a modified dot-probe task that only contains incongruent trials (i.e., target-dot - neutral stimulus 100% pairing).
|Active Comparator: Attention Control
Behavioral: Attention Control
Attention control (AC) sessions, will consist of a standard dot-probe task (i.e., target-dot - neutral/threat stimulus 50% pairing). Thus, for AC participants, bias should remain the same, while ABM participants should show a reduced bias to threat.
Primary Outcome Measures
- Attentional Bias [Baseline and after 6 weeks of the intervention]
Reaction time difference to congruent and incongruent trials in the dot-probe task, which measure heightened attentional bias to threat.
Secondary Outcome Measures
- State and Trait Anxiety [Baseline and after 6 weeks of the intervention]
Anxiety as measured by the Speilberger State-Trait Anxiety Inventory
Other Outcome Measures
- MRI measures of gray matter volume [Baseline and after 6 weeks of the intervention]
T1-weighted MRI measures of gray matter volume
- MRI measures of structural and functional connectivity [Baseline and after 6 weeks of the intervention]
Diffusion-tensor weighted MRI based measures of structural connectivity and functional MRI based measures of functional connectivity.
Handedness (right handed)
Preexisting Attentional Bias
No MRI contraindications
No History of Head Injury
No Neurological History
Limited Recreational Drug Use, No Abuse
Limited Prescription Drug Use, No Abuse
Contacts and Locations
|1||Northern Michigan University||Marquette||Michigan||United States||49855|
Sponsors and Collaborators
- Northern Michigan University
- National Institute of Mental Health (NIMH)
- Principal Investigator: Joshua M Carlson, PhD, Northern Michigan University
Study Documents (Full-Text)None provided.