Neuroplastic changes in anterior cingulate cortex gray matter volume and functional connectivity following attention bias modification in high trait anxious individuals.

Attention bias modification (ABM) was developed to alleviate anxious symptoms by way of a reduction in anxiety-linked attentional bias to threat. Central to the rational of ABM is a learning-related reconfiguration of attentional biases. Yet, the neuroplastic changes in brain structure that underlie this learning are unresolved. The amygdala, anterior cingulate cortex, and lateral prefrontal cortex are part of a system linked to attentional bias to threat and its modification with ABM. We assessed the extent to which ABM modulates gray matter volume and resting-state functional connectivity. Sixty-one individuals selected for attentional bias to threat and heightened trait anxiety completed a 6-week multi-session ABM protocol with 7200 total training trials. Participants were assigned to either an ABM (n = 30) or a control (n = 31) condition. We found that participants' levels of attentional bias and anxiety did not differ following ABM and control training interventions. However, the ABM group displayed greater levels of anterior cingulate cortex gray matter volume as well as greater superior frontal gyrus resting-state functional connectivity with the anterior cingulate cortex and insula. Changes in anterior cingulate cortex gray matter volume were linked to reduced anxious symptoms in the ABM, but not control, group. These findings suggest that ABM distinctively impacts structural and functional neural mechanisms associated with emotion reactivity and cognitive control processes.

Dorsal anterior cingulate cortex intrinsic functional connectivity linked to electrocortical measures of error monitoring.

The error-related negativity (ERN) is a response-locked event-related potential, occurring approximately 50 ms following an erroneous response at frontocentral electrode sites. Source localization and functional magnetic resonance imaging (fMRI) research indicate that the ERN is likely generated by activity in the dorsal anterior cingulate cortex (dACC). The dACC is thought to be a part of a broader network of brain regions that collectively comprise an error monitoring network. However, little is known about how intrinsic connectivity within the dACC-based error monitoring network contributes to variability in ERN amplitude. The purpose of this study was to assess the relationship between dACC functional connectivity and ERN amplitude. In a sample of highly trait anxious individuals, the ERN was elicited in a flanker task and functional connectivity was assessed in a 10-min resting-state fMRI scan. Results suggest that the strength of dACC seeded functional connectivity with the supplementary motor area is correlated with the ΔERN (i.e., incorrect-correct responses) amplitude such that greater ΔERN amplitude was accompanied by greater functional coupling between these regions. In sum, ERN amplitude appears to be related to the strength of functional connectivity between error monitoring and motor control regions of the brain.

Single session positive attention bias modification training enhances reward-related electrocortical responses in females.

Positive affect is linked to greater mental and physiological well-being. Conversely, negative affect is linked to depressive symptoms such as anhedonia. Relative biases in attention to positive or negative emotional information are thought to underlie individual difference in positive and negative affective traits, respectively. Attention bias modification (ABM) increases positive affect by training attention away from negative, or toward positive, stimuli. ABM training to reduce bias to negative information modulates electrocortical activity (i.e., P2, N2, & P3 ERP amplitudes), and this effect is moderated by participant sex. The extent to which ABM training to positive stimuli alters electrocortical activity and the extent to which such changes are moderated by participant sex is unknown. Here, participants completed attend positive ABM (or control) training followed by assessments of attentional bias, mood, and reward-related electrocortical activity. The results provide evidence of greater attentional bias to positive information following ABM. Transfer of these training effects to electrocortical measures was found for the P2 ERP component and moderated by participant sex. Females displayed a larger P2 amplitude for positive outcomes following ABM training. The reward positivity (RewP) and P3 ERPs were not directly affected by training, but the relationship between ERPs was linked to training such that following ABM training, the P2 and RewP components were strongly correlated, while following control training, the P3 and RewP were moderately correlated. Thus, ABM training to positive information enhanced electrocortical measures of reward processing in females and increased the relationship between reward-related ERPs.