Differential amygdala activation during emotional decision and recognitionmemory tasks using unpleasant words: an fMRI study

This study used fMRI to examine the response of the amygdala in the evaluat ion and short-term recognition memory of unpleasant vs. neutral words in ni ne right-handed healthy adult women. To establish specificity of the amygda la response, we examined the fMRI BOLD signal in one control region (visual cortex). Alternating blocks of unpleasant and neutral trials were presente d. During the emotional decision task, subjects viewed sets of three unplea sant or three neutral words while selecting the most unpleasant or neutral word, respectively. During the memory task, subjects identified wards that were presented during the emotional decision task (0.50 probability). Image s were detrended, filtered, and coregistered to standard brain coordinates. The Talairach coordinates for the center of the amygdala were chosen befor e analysis. The BOLD signal at this location in the right hemisphere reveal ed a greater amplitude signal for the unpleasant relative to the neutral wo rds during the emotional decision but not the memory task, confirmed by Tim e Course x Word Condition ANOVAs. These results are consistent with the mem ory modulatory view of amygdala function, which suggests that the amygdala facilitates long-term, but not short-term, memory consolidation of emotiona lly significant material. The control area showed only an effect for Time C ourse for both the emotional decision and memory tasks, indicating the spec ificity of the amygdala response to the evaluation of unpleasant words. Mor eover, the right-sided amygdala activation during the unpleasant word condi tion was strongly correlated with the BOLD response in the occipital cortex . These findings corroborate those by other researchers that the amygdala c an modulate early processing of visual information in the occipital cortex. Finally, an increase in subject's state anxiety (evaluated by questionnair e) while in the scanner correlated with amygdala activation under some cond itions. (C) 2001 Elsevier Science Ltd. All rights reserved.