Abstract
Emotional responses are thought to play a vital role in survival and in our ability to adapt to our environment. It has been suggested that the mechanism by which we process emotional information consists of evaluative, experiential, and expressive components. However little is known about human emotional responses in the brain. From these standpoints, we have done neuroimaging analyses to explore human emotional responses in the brain used by a functional magnetic resonance imaging (fMRI) in healthy volunteers and depressed patients. Brain activation was measured in healthy subjects while the subjects performed a warned reaction task using pictures which evoked emotionally pleasant or unpleasant content, because evaluation in the present of emotional events that are destined to happen in the future is a necessary form of adaptive behavior. These data suggest that left prefrontal cortex (PFC) activation is associated with the expectancy of pleasant stimuli and that right PFC activation is associated with the expectancy of unpleasant stimuli. We also investigated the brain activity associated with the expectancy of emotional stimuli in depressed patients. In contrast to healthy control, depressed subjects showed attenuated activation in the left PFC during pleasant stimuli and increased activation in the right PFC during unpleasant stimuli. These findings suggest that abnormal emotional responses in depressed patients are associated with altered brain activities within these regions during the warned reaction task. [Jpn J Physiol 55 Suppl:S17 (2005)]
