Abstract: Sign-tracking and goal-tracking are essentially conditioned approach responses which are induced by pairings of conditioned stimulus (CS) and unconditioned stimulus (US). The predictive and incentive motivational properties of CS are important mechanisms of sign-tracking and goal-tracking. The nucleus accumbens, the central nucleus of the amygdala and the anterior cingulate cortex are required for sign-tracking and goal-tracking. But lesions of the cerebral cortex and hippocampus have little effect on sign and goal tracking. Reduced brain dopaminergic function impairs acquisition and expression of sign-tracking. Increased dopamine content in brain can promote goal-tracking. It will be important for future research to standardize categories and settings of CSs and USs, separately or simultaneously measuring sign-tracking and goal-tracking in terms of different research purposes.

Key words: sign-tracking, goal-tracking, conditioned approach responses, incentive motivation, dopamine