Using the Stop-Signal Task to Identify a Bio-Marker of Anxiolytic Action in the Human Brain

ii According to Gray and McNaughton (2000), anxiety is the result of conflict between simultaneously activated approach and avoidance tendencies. The function of the Behavioural Inhibition System (BIS) is to resolve this conflict between goals that are equally activated with regard to strength and timing. Conflict resolution is thought to involve recursive computation in cortico-hippocampal loops resonating at the rodent hippocampal frequency (4-12Hz, “theta”). The BIS theory is based on findings from the animal literature, but recently, attempts have been made to apply it to humans. Neo, Thurlow, and McNaughton (2011) used the stop signal task (SST) to elicit and measure activation of the BIS in humans. They used a novel analysis, dividing trials so that a high approach-avoidance conflict condition could be compared against the average of non-conflict conditions of approach and avoidance. They found increases in “theta” activation over the right frontal cortex during the high conflict condition. They interpreted this as being consistent with activation of the BIS. The size of this activation was als