Anticipatory anxiety-induced changes in human lateral prefrontal cortex activity

It has been suggested that frontal brain asymmetry is associated with differences in basic emotional dimensions, particularly in activation of systems underlying avoidance-withdrawal behavior. We examined regional cerebral oxygenated hemoglobin (O2Hb) levels in human medial prefrontal cortex (MPFC) using near-infrared reflection spectroscopy (NIRS) prior to and during anticipatory anxiety to determine if NIRS could detect any anxiety-related changes. Transient anxiety was induced in 56 normal volunteers by anticipation and a painful shock to the right-hand's median nerve. Pre- and post-anxiety affective statuses were measured using the State-Trait Anxiety Inventory (STAI) and Temperature Character Inventory (TCI). NIRS recorded from the left and right frontal brain regions. Right MPFC O2Hb was significantly increased relative to left MPFC O2Hb during anticipation of the shock. Right-sided O2Hb increases were significantly correlated with the TCI Harm Avoidance subscale. These results support the hypothesis that O2Hb levels in the right frontal region correlate with anxiety or heightened negative affect.