People across cultures and throughout history report spiritual experiences that involve a sense of union transcending the ordinary self, but their neural mechanisms are poorly understood. Using an individualized guided-imagery task, the authors compared brain activity during personally meaningful spiritual experiences with that during stressful and neutral-relaxing experiences. During spiritual experiences, the left inferior parietal lobule showed reduced activity compared to neutral-relaxing experiences, suggesting this region contributes to perceptual processing and self-other representations. Compared to stress cues, spiritual cues reduced activity in the medial thalamus and caudate, regions linked to sensory and emotional processing. The findings point to neural mechanisms underlying broadly defined, personally experienced spirituality.
Ketamine, an NMDAR antagonist, increased oxidative metabolism (CMRO2) and cerebral blood flow in the prefrontal cortex and other cortical regions, but did not alter resting-state cortical functional connectivity or brain-wide CBF-CMRO2 coupling. Higher baseline CMRO2 was associated with lower task-related prefrontal activation and greater working memory accuracy impairment under both saline and ketamine conditions. These findings suggest that CMRO2 and resting-state functional connectivity index distinct dimensions of neural activity, and that ketamine's impairment of working memory-related neural activity and performance relates to its induction of cortical metabolic activation.