Question: Do you think that science can ever completely understand human emotion and its link to the brain? I saw a programme about heart transplants and the personality and emotional changes that they can produce in the recipient - do you think that the heart has unkown links to the \"soul\" and the way our personalities and emotions work?

Carolyn McGettigan answered on 17 Mar 2010:

I think psychology has gone some way in looking at how emotions are expressed and recognised, both in our faces, in speech and in other vocalizations that don’t have words (like laughing, crying and screaming). There is already a lot of evidence from neuroscience, for example showing that the brain area called the amygdala is involved in responding to fearful situations while the insula responds to basic feelings of disgust (e.g. in response to a bad smell).

A study my supervisor ran looked at how our brains respond (in MRI) to emotional vocalizations and found that these sounds activate auditory cortex. However, those sounds that were more positive, like laughter and cheering, engaged the parts of our brain that we use to actually produce these sounds, in motor cortex. This might be linked to how these sounds are used in group behaviour – we tend to laugh with other people, and it is a pleasant, cohesive activity. Laughter is contagious! We’re now developing a new study to see if and how our brains tell the difference between fake laughs and real ones – will the motor cortex activate more for the genuine laughs that we might like to join in with?

Things get more complicated for more complex emotions like jealousy and patience. These are probably harder to measure in people’s behaviour and so I guess this will make identifying how the brain copes with these more difficult.

As for your second question: Sometimes these reports of people’s personality changes after organ transplants seem quite compelling, especially in those cases where the change in personality is accompanied by development new interests or ‘talents’ that the patient didn’t display before. However, I do not at all believe that we can inherit other people’s personalities. Our personalities are in our brains – I’m 100% certain of this.

Actually, I think the media coverage of stories like this is rather irresponsible. I appreciate that receiving an organ donation is an extremely significant to the recipient – donor matches don’t come along that often, the surgery is very serious and good outcomes are not guaranteed. When the donation is a success it can radically improve the health of someone who has been unwell for a long time. The psychological aspects to this must be huge. At a basic level, feeling healthier physically is likely to lead to improvements in mood and this might extend to taking up new hobbies that weren’t interesting before when life was harder e.g. painting or music. In more complex ways, organ recipients might feel that they owe it to their donor to live life to the full, and maybe they might even find it helpful to feel that some aspect of the donor’s personality can ‘live on’ in them. However, many positive things can happen without them having anything to do with the actual donor tissue ‘containing’ anything to do with personality. That just doesn’t happen. It worries me that these ‘weird science’ aspects of transplant stories take precedence over the true positive outcomes of the surgery, which are that someone’s donated organ can radically improve the health of a sick person and give them a new lease of life.