I have conducted an fMRI study comparing recovered anorexia nervosa patients to healthy controls on an emotional stroop task. The task consists of fearful and happy faces, overlaid with either the word 'fear' or 'happy'. Thus, a given trial can either be congruent (face and word match) or incongruent (face and word mismatch). The task was to designate if the face was happy or fearful, ignoring the word. Reaction time data showed that it takes longer to respond to incongruent trials compared to congruent trials, which we expected.
However, the fMRI analysis shows that, for the control group, participants had more bilateral amygdala activation during congruent compared to incongruent trials (as shown by the extracted beta weights from left and right amygdala). I expected more amygdala activation for incongruent trials (thinking that an emotional conflict conveys more saliency). I am struggling to understand our observation.
Does anyone have any comments regarding this finding? All comments are highly appreciated!
Perhaps it has something to do with an emotional memory contribution? According to http://www.sciencedirect.com/science/article/pii/S000632230600583X
"Following sad mood induction, bilateral amygdala response during encoding of valenced words predicted increased recall of negative self-referent words..."
Thanks for the comments!
1. Steve: I doubt that it has something to do with emotional memory encoding, as congruent and incongruent trials are identical in all respects, except for the fact that the word and picture may either match or mismatch.
2. Davood: I also suspected that it might have something to do with the "double fear" information. However, this is not the case. The left and right amygdala respond equally to both types of congruent trials (that is, regardless of picture and word combination). It seems that the congruency between the picture and the word in itself leads to a heightened amygdala response.
It could be that the congruency between word and picture are more "salient", leading to increased amygdala activation. Incongruent trials however, convey a conflict which are processed in other areas, such as ventral anterior cingulate.
Perhaps this paper gives you a hint:
Conflict adaptation in emotional task underlies the amplification of target. Chechko, Natalia; Kellermann, Thilo; Schneider, Frank; Habel, Ute. Emotion 14.2 (Apr 2014): 321-330.
Here is an email address to someone who eventually could give you a good answer: [email protected]
Emotional processing is attenuated when task-demands are high (high cognitive load conditions) and during tasks that recruit executive control processes such as conflict resolution and inhibitory control.
See for example the opinion paper by Okon-Singer, Lichtenstein-Vidne, & Cohen, Biological Psychology, 2013
Thank you for your comments Noga and Beatrice!
This was just what I needed. Interpreting the findings in terms of an attenuation of emotional processing makes sense, and along the lines I was initially thinking.
Thank you so much!
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