Effective Connectivity Between Broca’s Area and Amygdala as a Mechanism of Top-Down Control in Worry

Abstract

Individuals higher in trait worry exhibit increased activation in Broca’s area during inhibitory processing tasks. To identify whether such activity represents an adaptive mechanism supporting top-down control, we investigated functional and effective connectivity of Broca’s area during a task of inhibitory control. Functional MRI data obtained from 106 participants performing an emotion-word Stroop task were examined using psychophysiological interaction and Granger causality (GC) analyses. Findings revealed greater directed connectivity from Broca’s area to amygdala in the presence of emotional distraction. Furthermore, a predictive relationship was observed between worry and the asymmetry in effective connectivity; worriers exhibited greater directed connectivity from Broca’s area to amygdala. When performing the task, worriers with greater GC directional asymmetry were more accurate than worriers with less asymmetry. Present findings indicate that individuals with elevated trait worry use a mechanism of top-down control in which communication from Broca’s area to amygdala fosters successful compensation for interference effects.

Alterations in the default mode‐salience network circuit provide a potential mechanism supporting negativity bias in depression

“…For each participant, relative frame displacement, calculated using FSL Motion Outliers, was regressed from each network seed's time course data prior to computation of GC in order to reduce the influence of motion artifact on analyses (Guha et al, 2019). Task blocks (4 positive, 8 neutral, 4 negative) were treated as repeated observations of each emotion condition and GC was run for each subject within each task condition.…”

“…A critique of fMRI GC concerns the indirect relationship between the BOLD response and neural activity (Ramsey et al, 2010). Specifically, relative to its application to EEG/MEG data, low temporal sampling rate is a concern in fMRI GC, restricting the interpretation of fMRI GC in terms of temporal resolution (see discussion in Guha et al, 2019).…”

“…Per this proposed mechanism, SAL suppresses DMN to promote disengagement from internally focused cognitive processes to promote activation of CEN for goal-directed behavior. Although a number of studies have implicated altered connectivity between amygdala, a region of the SAL, and frontal regions of the CEN in emotion dysregulation observed in psychopathology including depression (Carballedo et al, 2011;Dannlowski et al, 2009;Ferreira-Santos et al, 2012) and anxiety (Guha et al, 2019;Ironside et al, 2017), alterations in effective connectivity between DMN and SAL are less understood. The relationship between DMN and SAL is particularly relevant to tasks requiring the switching of attention between externally and internally generated stimuli and may be key to understanding mechanisms of rumination and attentional bias in depression (Gong et al, 2019;Ho et al, 2021;Shao et al, 2018).…”

“…Additionally, negativity bias in major depressive disorder is expected to endure even after a depressive episode resolves (Bower, 1981). Of participants who passed all MRI exclusion criteria (see (Guha et al, 2019)), 38 participants met criteria for a past major depressive episode, including four currently depressed. Fifty individuals meeting no major depressive disorder criteria, past or present, were included in the non-depressed comparison group.…”

EEG Frontal Asymmetry in Dysthymia, Major Depressive Disorder and Euthymic Bipolar Disorder

“…In line with this, it is worthwhile to mention a recent study showing, in individuals selected for high traits of worry, strong functional connectivity between Broca's area and the ipsilateral amygdala which is activated by negative stimuli. Thus, worrying tends to hyperactivate this amygdala-prefrontal cortex loop, strengthening negative thoughts and interpretations that represent one of the main clinical features of anxious-depressed patients: ruminations [45]. Given the high levels of anxiety measured in PDD patients, a similar experimental design could be applied to the study of connectivity in this neglected sample of patients.…”