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Tuesday, March 31, 2009

fMRI III: Religiosity & Brain Activation

The first installment of my trilogy on functional magnetic resonance imaging (fMRI) was published on Mar. 23, 2009. In the second installment, I discussed a study with a simple task design that yielded unequivocal results (Harrison and Tong, 2009). The present post contains the concluding essay of this trilogy. The tasks in that study involves abstract ideas, the judgment of which lie very much in the eye of the participant. Animal models that permit us to examine the nerve cell mechanisms underlying the observed cerebral activation are unavailable. Thus, the findings are more open to interpretation.

Dimitrios Kapogiannis and others at the National institute of Neurological Disorders and Stroke examined statistical associations between cerebral activation and religiosity, that is one's personal attitudes toward religious believes. The findings of this study were published online in The Proceedings of the National Academy of Sciences on Mar. 9, 2009, and the principal investigator discussed them with Jon Hamilton in a segment entitled "To The Brain, God Is Just Another Guy" on National Public Radio's All Things Considered the same day.

The study consisted of two parts. For the first part, the researchers recruited 26 people who proclaimed faith in a god to varying degree. The recruits were adults of both sexes with post-secondary school education. The participants were required to answer questions and score their sentiments concerning their (1) relational (2) emotional and (3) doctrinal/experiential appreciation of God. Statistical multi-factorial linear modeling was used to isolate three factors that best differentiated the participants' answers, quantifying their religiosity. The factors were then used to correlate profiles of cerebral activation with the profiles of answers typical for each aspect of religious belief.

For the second part, 40 participants of similar background as recruited for the first part answered the same questions, while their cerebral activation was mapped with fMRI. The factors that were associated strongest with the types of answer in the study's first part were used to determine the tightness of association between the recorded cerebral activation and the participants' religiosity. The researchers found foci of activation in all lobes of cerebral cortex. Local differences in activation were statistically significantly associated with the three types of question, regardless of religiosity. The observed regions are known to be engaged in higher cognitive processes:

  1. Only statements concerned with God's perceived lack of involvement in our lives influenced cerebral activation statistically significantly. Foci of activation were found in the frontal, temporal, occipital and parietal (precuneus) lobe on the right hemisphere as well as the left inferior frontal gyrus.
  2. Statements concerned with emotional affect influenced cerebral activation in the right frontal, (God's love) and the left temporal lobe (God's anger).
  3. Statements concerned with doctrinal religious knowledge influenced cerebral activation in the cingulate gyrus as well as in regions of the temporal and parietal lobes. Statements concerned with experiential religious knowledge affected cerebral activity in the parietal (precuneus), frontal, and occipital lobes, particularly in areas of early processing of visual input, that is primary (V1) and secondary visual (V2) cortex in both hemispheres. Occipital visual areas are activated during visual mental imagery, that is while seeing in front of your mind's eye.
Cerebral activation did not co-vary statistically significantly with religious or non-religious, except in the precuneus of the parietal lobe, the middle occipital gyrus of the occipital lobe and the middle frontal gyrus of the frontal lobe on the left hemisphere. In most people language is processed on the left hemisphere. However, a direct statistical comparison between the  religious and the non-religious did not yield any significant differences in cerebral activation.

The involvement of the precuneus in the processing of religious ideas is of note. This region of the parietal lobe is located on the inner surface of the cortical hemisphere adjacent to the cuneus of the occipital lobe and opposite angular gyrus at the temporoparietal junction on the outer surface of the cortical hemisphere. The cortical areas processing hearing, vision and touch meet at angular gyrus. Recording electrical nerve cell activity in in this part of cortex of monkeys, the eminent Italian neuroscientist Giacomo Rizzolatti and his colleagues found nerve cells that become active when the monkeys see their actions reflected in a mirror. Moreover, they were activated when the monkeys saw someone imitating their behavior. Rizzolatti named these nerve cells mirror neurons. He suggests that they are dedicated to processing shared experience, discussing the implications for the mind in a recent book entitled "Mirrors in the Brain: How Our Minds Share Actions, Emotions, and Experience". 

Foci of activation were found in this region in my own studies, when people with severe visual disabilities read Braille with their finger tips. I have described the findings in my post dated Dec. 9, 2007. Recently, this area has been implicated in out-of-body experiences (Arzy and others, 2006). Sandra Blakeslee reported on this discovery in her article entitled "Out-of-Body Experience? Your Brain Is to Blame" for The New York Times, published online Oct. 6, 2006. Taken together the observations above suggest that the regions in the posterior parietal lobe at the junction with the occipital lobe and the parietal lobe are engaged in the processing of language, thought, and self-consciousness, i.e. functions crucial for a brain-based Theory of Mind.  

The fact that Kapogiannis and others (2009) did not find a difference in brain activation related to religiosity may not be surprising. It is highly questionable whether faith in God has the same meaning to all faithful, even if they claim to believe in a god most fervently. Our concepts of God and the doctrine associated with the belief vary and may remain elusive. The most homogeneous group of religious believers to recruit from may consist of monastic clergy. However, even the most devout may carry a grain of doubt. As we know from her private correspondence with Pope John Paul II, Mother Theresa devoted her life to charitable work in the search of God, only to worry deeply that He might not be there in the end.

Perhaps, it was impossible to compose a sample in which the prevalence of the religious and non-religious is balanced. According to a recent Fox News poll, 92 percent of Americans believe in God, 85 percent in heaven and 82 percent in miracles. Furthermore, according to The Economist, roughly 50 percent of Americans believe that the theory of evolution is false. Under these circumstances, the non-religious may have been underrepresented in the sample, providing too small a contrast to permit the researchers to ascertain differences in cerebral activation between the religious and the non-religious.

The findings of this study could affirm, however, that particular networks of nerve cells distributed across cerebral cortex represent specific types of concepts detached from any one sense, though distinct activation patterns for the faithful remained elusive. The loci of spirituality eluded our grasp once more.

Addenda
  • You may wish to watch Rizzolatti's discovery in a video clip shown on "Charlie Rose Brain Series Episode Four: The Social Brain" originally aired Jan. 19, 2010. The video begins 15:36 minutes into the broadcast. The gushing sound is produced with an audio-monitor that tracks electrical nerve cell activity recorded from thin micro-wire electrodes implanted in the monkey's cerebral cortex. Note that the nerve cell activity increases when the monkey reaches for food as well as when the trainer mimics reaching for food (09/08/10).
  • In his book "Principles of Neurotheology", Andrew Newberg strives to lay out a foundation for neurotheology. Listen to this interview by Neal Conan on National Public Radio's Talk of the Nation with the title "Neurotheology: This Is Your Brain On Religion" broadcast yesterday (12/15/10).

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