Brain activity underlying mental imagery: Affective versus neutral stimuli

The purpose of this study was to extend the determination by Martha Farah and her colleagues of an Event Related Potential (ERP) "marker" for image generation (i.e., slow, late positive waves in the occipital and parietal regions of the brain) beyond the level of what has been termed a "cognitive code" (i.e., image). This was carried out by introducing emotionally charged stimuli (i.e., affect) to the original experimental prototype. Highly significant differences were found between every condition under consideration. While patterns of ERP positivity were found in the left hemisphere, similar to Farah's results, they were strongly parietal and centro-parietal in nature. Thus, there was no direct evidence of relative occipital positivity found in this study.;Regarding the central question of this study ("Did emotionally laden stimuli produce ERP patterns similar to the neutral conditions?"), the results were quite dramatic. There was a broad shift of positivity from the centro-parietal activity of Condition 4 (Imaging) into the frontal areas under Condition 5 (Emotional Imaging). This pattern exhibited strong replicability over a broad range. It can thus be equitably stated that under these design conditions, emotional stimuli established ERP patterns which uniformly superseded those which have been purported to represent "cognition" (i.e., neutral image generation).;These results may have implications regarding the primacy and independence of affect relative to that of cognition in psychotherapeutic theory and practice.