Remembered or forgotten stimuli: a functional magnetic resonance imaging study on the effects of emotion

Objective: The first aim of this study is to examine why emotional events enhance memory for preceding stimuli. The second goal is to identify brain regions associated with remembering and forgetting by finding brain activation differences during encoding of remembered and forgotten stimuli. The third goal is to examine which brain areas are activated when studying emotional pictures compared to neutral ones. Method: In each trial, a picture of an object followed by an emotional or neutral picture from the Turkish culture were presented to 15 volunteers. The effect of the succeeding pictures on the remembering of preceding stimuli was examined. The participants studied the stimuli in the magnetic resonance scanner and, meanwhile, brain images were taken. The memory performances of the participants were measured with the recognition test administered one week later. Results: Behavioral results suggest that emotion has no effect on memory for preceding stimuli. Functional magnetic resonance imaging results indicate that remembered stimuli compared to forgotten ones caused more activation in left inferior frontal gyrus and left superior medial gyrus. Emotional pictures create more activation in the - mid-temporal gyrus and supramarginal gyrus compared to neutral images. Conclusion: Brain structures in which activations are observed in remembered stimuli compared to forgotten ones (left inferior frontal gyrus and left superior medial gyrus) are responsible for the semantic elaboration and associative memory formation. Thus, it can be concluded that object pictures are remembered because they are processed more deeply. Besides, activations are observed in the areas known to be related to the processing of emotional face expressions when emotional and neutral pictures are compared.