Wednesday, May 4, 2011

Neuroethics: The Brain and Moral Beliefs

Jerome Grafman, Ph.D. presented the May 2011 Warren Frontiers in Neuroscience lecture “Brain Regions Supporting the Establishment of Human Beliefs” in Tulsa, Oklahoma.  I have typically summarized these lectures in a single Brain Posts blog posting.  But given the broad character of this presentation, I will break my summary into three parts based on the sections in the presentation: moral beliefs, religious beliefs and political beliefs.  Along with the lecture highlights, I will review relevant research manuscripts by Dr. Grafman and his research team.

A first step in studying concepts as abstract as morality is to define key components or factors within moral beliefs.  This is a common approach applicable to also religious and political beliefs.  Dr. Grafman prefers a more data driven approach to this task, rather than coming from a theoretical perspective.  The Moral Sentiment Task is a 98-item interview where subjects are given a scenario and asked to pick one of four responses that describes the feeling they would experience in that situation.  Using large population survey data, responses in this interview can be assigned to one of two sentiments:

Prosocial sentiments
  • embarrassment 
  • pity
  • guilt
Critical sentiments
  • anger
  • disgust
In a study with Jorge Moll and colleagues, Grafman examined a series of patients with frontotemporal dementia (FTD) using PET imaging and the Moral Sentiment Task.  Patients with FTD commonly exhibit impairment in social behaviors such as acting inappropriately (misjudge the social appropriateness of a behavior).  This socially inappropriate behavior commonly causes caregiver embarrassment and makes FTD often more difficult to manage than Alzheimer’s dementia.  Since the frontal lobe is felt to contribute to moral beliefs and judgment, a disease variably affecting the frontal lobe is likely to provide information about the effect of deficits in specific regions.

Patients with FTD were recruited for a study of the relationship between hypoactivation of specific brain regions with impairment in making accurate choices in the Moral Sentiment test.  As expected FTD, patients showed widespread decreased frontal lobe glucose utilization compared to controls.  In a correlational analysis, the following results were noted:
  • Decreased glucose utilization in the medial frontopolar cortex correlated with reduced prosocial sentiment
  • Decreased glucose utilization in the septum also correlated with impaired prosocial sentiment
  • Decreased glucose utilization in the dorsal medial prefrontal cortex and the amygdala correlated with reduced critical sentiment scores

In a review in the Annual Review of Neuroscience, Forbes and Grafman summarize the role of the prefrontal cortex in social cognition and moral judgment.  They note that there is significant overlap between processes involved in social cognition and moral judgment.  Social cognition has been described as the encoding, storage, retrieval and processing in the brain of information related to other members of the species. 

Elements of social cognition function can be implicit processes (occurring rapidly with little cognitive effort and outside conscious awareness) or explicit processes (deliberate, cognitively taxing and consciously accessible).  Implicit social cognition appears to have evolved earlier and is linked to the posterior cortex and subcortical regions.  Explicit social cognition evolved later and relies heavily on the prefrontal cortex (PFC). 

The prefrontal cortex appears to be a key area involved in making moral judgments.  Using fMRI brain PFC regions activate with processing a moral challenge.  Interestingly, the specific region of PFC involved in making a decision appears to be separate for making a decision on an impersonal moral dilemma (whether to flip a trolley track switch that will save five lives but lead to the death of one other person) or a personal moral dilemma (whether to smother your own crying baby if doing so would being detected by oppositional soldiers who will kill you and many other individuals).

Forbes and Grafman note in the conclusion of their review that “social interactions and judgments of humans have been based on evolutionary pressures and environmental and social contingencies”.  This evolution is continuing and they wonder if more impersonal world of advances such as Facebook and text messaging at a young age might drive the brain systems towards more “immediate results and gratification”.  Nevertheless, the emerging field of social neuroscience is likely to play a key role in better understanding neuroanatomical, genetic and environmental influences that effect our social development and the moral judgment we make.

Screen shot of prefrontal cortex from 3D Brain by Yates Photography.

In the next post, I will summarize research related to the brain and religious beliefs.  Dr. Grafman’s proposes an answer to the question “Is there a God spot in the brain?”

Moll J, Zahn R, de Oliveira-Souza R, Bramati IE, Krueger F, Tura B, Cavanagh AL, & Grafman J (2011). Impairment of prosocial sentiments is associated with frontopolar and septal damage in frontotemporal dementia. NeuroImage, 54 (2), 1735-42 PMID: 20728544

Forbes, C., & Grafman, J. (2010). The Role of the Human Prefrontal Cortex in Social Cognition and Moral Judgment Annual Review of Neuroscience, 33 (1), 299-324 DOI: 10.1146/annurev-neuro-060909-153230

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