Current concepts of the extended amygdala posit that basolateral to central amygdala projections mediate fear-conditioned autonomic alerting, whereas projections to the bed nucleus of the stria terminalis mediate sustained anxiety. Using DTI tractography in humans, we show that microstructure of the stria terminali correlate with an orienting bias toward threat in a saccade decision task, providing the first evidence that this circuit supports decisions guiding evaluation of threatening stimuli.