Individual variability in the locus of prefrontal craving for nicotine: implications for brain stimulation studies and treatments

Abstract

Background: Attenuation of cue-elicited craving with brain stimulation techniques is a growing area of attention in addiction research. This investigation aims to guide these studies by assessing individual variability in the location of peak cortical activity during cue-elicited craving.

Method: Twenty-six nicotine-dependent individuals performed a cue-elicited craving task in a 3T MRI scanner while BOLD signal data was collected. The task included epochs of smoking cues, neutral cues, and rest. The location of peak activity during smoking cues relative to neutral cues ('hot spot') was isolated for each individual. The spatial dispersion of the 26 cue-elicited hot spots (1 per participant) was quantified via hierarchical clustering.

Results: When viewing nicotine cues all 26 participants had at least one cluster of significant prefrontal cortex activity (p<0.05, cluster corrected). Only 62% had peak activity in the medial prefrontal cortex cluster (including 100% of the men). In 15% of the participants peak activity was located in either the left lateral prefrontal cortex or left insula cluster. Peak activity in the remaining 23% was dispersed throughout the prefrontal cortex.

Conclusion: There is considerable individual variability in the location of the cue-elicited 'hot spot' as measured by BOLD activity. Men appear to have a more uniform location of peak BOLD response to cues than women. Consequently, acquiring individual functional imaging data may be advantageous for either tailoring treatment to the individual or filtering participants before enrollment in treatment.