Emotions influence our perception and decision making. It is of great importance to understand the neurophysiology behind these processes as they influence human core functions. Moreover, knowledge within this field is required in order to develop new medical therapies for pathological conditions that involve dysregulation of emotions. In this thesis the neural mechanisms of emotional regulation and decision making were investigated using different pharmacological manipulations and brain imaging. In Study I, we examined whether a CCKb-receptor and a mu-opioid receptor agonist could modulate emotional perception of visual stimuli in opposite directions. In Study ...