Researchers link spirituality and religious belief to brain circuitry
Using datasets from neurosurgery patients and people with brain damage, researchers mapped the locations of damage associated with spiritual and religious beliefs to a specific human brain circuit.
More than 80% of people in the world consider themselves religious or spiritual. But research on the neuroscience of spirituality and religiosity has been sparse. Previous studies have used functional neuroimaging, in which an individual undergoes a brain scan while performing a task to see which areas of the brain light up. But these correlative studies have given an uneven and often inconsistent picture of spirituality. A new study by researchers from Brigham and Women’s Hospital takes a new approach to mapping spirituality and religiosity and finds that spiritual acceptance can be localized to a specific brain circuit. This brain circuit is centered in the periaqueductal gray (PAG), a region of the brainstem involved in many functions, including fear conditioning, pain modulation, altruistic behaviors and unconditional love. The team’s findings are published in Biological psychiatry.
“Our findings suggest that spirituality and religiosity are rooted in fundamental neurobiological dynamics and deeply woven into our neuro-tissue,” said the corresponding author. Michael Ferguson, Ph.D.Brigham’s Principal Investigator Brain Circuit Therapy Center. “We were amazed to find that this brain circuit for spirituality is centered in one of evolution’s best-preserved brain structures.”
To conduct their study, Ferguson and his colleagues used a technique called lesion network mapping that allows researchers to map complex human behaviors to specific brain circuits based on the location of brain damage in patients. The team mined from a previously published dataset that included 88 neurosurgery patients who were undergoing surgery to remove a brain tumour. Lesion locations were distributed throughout the brain. Patients completed a survey that included questions about spiritual acceptance before and after surgery. The team validated their findings using a second dataset of more than 100 patients with injuries caused by penetrating head trauma from combat during the Vietnam War. These participants also completed questionnaires that included questions about religiosity (such as “Do you consider yourself a religious person? Yes or No?”).
Of the 88 neurosurgical patients, 30 showed a decrease in self-reported spiritual belief before and after neurosurgical brain tumor resection, 29 showed an increase, and 29 showed no change. Using lesion network mapping, the team found that self-reported spirituality corresponded to a specific brain circuit centered on the PAG. The circuit included positive nodes and negative nodes – lesions that disrupted these respective nodes decreased or increased self-reported spiritual beliefs. The results on religiosity from the second data set are aligned with these results. Additionally, in a review of the literature, the researchers found several case reports of patients becoming hyper-religious after sustaining brain damage affecting the negative nodes of the circuit.
The locations of lesions associated with other neurological and psychiatric symptoms also intersected with the circuit of spirituality. Specifically, lesions causing parkinsonism intersected with positive areas of the circuit, as did lesions associated with decreased spirituality. Lesions causing delusions and foreign limb syndrome intersected with negative regions, associated with increased spirituality and religiosity.
“It is important to note that these overlaps may be useful for understanding shared characteristics and associations, but these results should not be overinterpreted,” Ferguson said. “For example, our results do not imply that religion is an illusion, that historical religious figures have suffered from alien limb syndrome, or that Parkinson’s disease is due to a lack of religious faith. Instead, our results point to the deep roots of spiritual beliefs in a part of our brain that has been involved in many important functions.”
The authors note that the datasets they used do not provide rich information about patient education, which may influence spiritual beliefs, and that patients in both datasets were primarily from Christian cultures. To understand the generalizability of their findings, they would need to replicate their study in many settings. The team is also interested in untangling religiosity and spirituality to understand the brain circuitry that may be at the root of the differences. Additionally, Ferguson would like to pursue clinical and translational applications of the findings, including understanding the role that spirituality and compassion can have in clinical treatment.
“It’s only recently that medicine and spirituality have been separated from each other. There seems to be this enduring union between healing and spirituality across cultures and civilizations,” Ferguson said. “I’m interested in how our understanding of brain circuitry could help shape scientifically grounded and clinically translatable questions about how healing and spirituality can co-inform.”
Ferguson MA, Schaper FLWVJ, Cohen A, et al. A neural circuit for spirituality and religiosity derived from brain-damaged patients. Biological psychiatry. 2021;0(0). do I:10.1016/j.biopsych.2021.06.016
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