The differences in neural network activity between methamphetamine abusers and healthy subjects performing an emotion-matching task: Functional MRI study

Methamphetamine (MA) abusers commonly exhibit socially problematic behaviors, such as diminished empathy, decreased emotional regulation and interpersonal violence, which may be attributable to alterations in emotional experience. However, few studies have used functional MRI to examine directly the emotional experience of threatening or fearful non-face images in MA abusers. In this study, we investigated possible differences in neural correlates of negative emotional experiences between abstinent MA abusers and healthy subjects using complex visual scenes depicting fear or threat derived from the International Affective Picture System. In within-group analyses, healthy subjects and MA abusers activated a similarly distributed cortical network, prominently including the amygdala, fusiform gyrus, parahippocampal gyrus, ventrolateral prefrontal cortex and inferior frontal cortex. In between-group analyses, however, MA abusers showed a reduced activation in the bilateral dorsolateral prefrontal cortex and insula, and increased activation in the fusiform gyrus, hippocampus, parahippocampal gyrus and posterior cingulate cortex, relative to healthy subjects. Hypoactivation of the insula in MA abusers relative to healthy subjects suggests that the ability to have an emotional response to threatening scenes and empathy for another's pain could be compromised in MA abusers. Hyperactivity in the fusiform gyrus, parahippocampal gyrus and posterior cingulate cortex in MA abusers relative to healthy subjects indicates that threatening and fearful images from the International Affective Picture System may remind MA abusers of episodic memory related to similar experiences. Therefore, functional impairment of these neural networks in MA abusers may contribute to altered emotional experience in social interactions, which could lead to increased negative mood and stress in interpersonal communication.