Human Anxiety-Specific "Theta" Occurs With Selective Stopping and Localizes to Right Inferior Frontal Gyrus

Anxiety disorders have high prevalence and generate major disability. But they have poor treatment targeting because psychiatry lacks diagnostic biomarkers. Right frontal goal-conflict-specific-rhythmicity (GCSR) in the simple stop signal task appears homologous to hippocampal "theta" as an anxiety-process biomarker but is weak and transient. An anticipatory response inhibition task (ARIT) elicits strong subjective conflict and so might generate stronger GCSR. Healthy participants provided EEG during an ARIT, which allowed direct comparison of selective (left, SG; right, GS), and nonselective (both, SS) handed stopping. We assessed GCSR as intermediate versus the average of short and long delay stop-specific power. SG produced right frontal 5-12 Hz GCSR that, as in the SST: significantly correlated with trait anxiety and neuroticism; and was sensitive to pregabalin (75 mg), buspirone (10 mg), and perhaps triazolam (0.25 mg). GS and SS produced faster stopping and only 9-10Hz GCSR, which did not correlate significantly with trait anxiety or neuroticism and was sensitive to pregabalin and buspirone but not triazolam. Source localization suggested that GCSR, like stopping, involves multiple right frontal circuits that depend on response speed. Anxiolytic-sensitive GCSR generalizes from the speeded stop signal task to fixed-time anticipatory response inhibition tasks. GCSR, and the circuits engaged, vary with stop signal RTs conditions. Tasks with longer stop times may be optimal to generate GCSR homologous with rodent hippocampal theta as (a) the first direct anchor of a specific neural form of trait anxiety; (b) a single-dose screen in normal humans for novel anxiolytics; and (c) a potential clinical anxiety biomarker.