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Abstract:
Three patterns of findings regarding the possible functions
of the retrosplenial cortex are apparent in the functional
neuroimaging literature. Retrosplenial cortex is frequently
activated during: 1) emotional conditions; 2) episodic memory
tasks; 3) "baseline" conditions compared to active cognitive tasks
(suggesting tonic activation in a "default state" of the awake
brain). Using fMRI, we previously demonstrated retrosplenial
activation during an affective evaluation task involving repeated
emotionally salient compared to neutral words. In this study, we
will present new fMRI data examining the effect of stimulus
repetition and evaluation task on retrosplenial activation by
emotional words. We will also present data on episodic memory
performance with the same emotional and neutral words. These data
will allow us to address several questions about the previously
observed retrosplenial activation during the affective evaluation
of repeated emotional words: 1) Is this activation only seen with
repeated stimuli (e.g. does it reflect a differential rate of
habituation to repeated emotional compared to repeated neutral
stimuli)? 2) Does it reflect processes related to the "default
state" of the brain, due to a confound between task difficulty and
emotional salience? 3) Does it reflect enhanced episodic memory
acquisition for the emotionally salient words? The findings will be
discussed in relation to the three previously proposed functional
correlates of retrosplenial activation: emotion, episodic memory,
and a "default state" of the brain.
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