Someone else’s pain—Are you in or out?

One of the bits of the brain I find the toughest to understand is the insula.  We hear about it when the “pain matrix” is discussed.  The insula is part of what is currently understood as the medial pain system— involved in assigning meaning, emotion and affect to the pain experience[1].  Various neuroimaging studies have found activity in the insula during empathy for pain[2].

Just when I thought I might have got my head around it, findings like these go and add more details into mix.  I’m referring to a paper here by Mazzola and colleagues in Italy[3].

This investigation delves a little deeper than your average neuroimaging-of-insular-function-in-empathy study.  If only we had a dollar for every one of them, hey?!  This study aimed to investigate whether and how individual differences in affective-cognitive styles are associated with activity in the insula during feelings of empathy for a loved one.

Here’s the simple bit first: in order to image the brain in a state of empathy, the participants watched a series of photographs depicting faces of a loved one in painful and neutral situations.  Unfamiliar faces (actors) in neutral and painful situations were used as controls.

Here’s the not-so-simple bit—the method of grouping participants according to different affective-cognitive styles.  Interviews and questionnaires placed participants into two categories of dispositional affect, according mainly to the way a person feels situated within their own environment.

1. Inward disposition:  subjects with a “better knowledge of basic emotions”, who tend to be more viscerally aware and more sensitive to changes in bodily states that occur during emotions and feelings.  These people have a body-centered coordinate system.
2. Outward disposition: subjects with a “better knowledge of non-basic emotions”.  These people rely on some kind of relationship between the self and external points of reference; their frame of reference is externally anchored i.e. rules, contexts, other people and norms.

These were the main findings: those subjects with an inward disposition displayed more activation in the left posterior insula and the right parietal lobe.  Those with an outward disposition showed more engagement in the bilateral dorsolateral prefrontal cortex, the bilateral precuneus (medial surface of the parietal cortex) and the left posterior cingulate cortex.  Incidentally, an interaction analysis of the familiarity factor (loved one’s pain vs. a stranger’s pain) revealed that painful faces from loved ones evoked greater activity in most parts of the brain in both groups. 

In other words, the engagement of the insula in emotional experiences is modulated by one’s dispositional affect.  Imaging in the inward group revealed a greater activation in brain regions involved in mapping our internal bodily states and subjective feelings.  Those with an outward disposition demonstrated activation in regions involved in gathering information from our external world.  Seems very tidy.

A little too tidy?  A source of concern with some neuroimaging studies (and I’m not saying necessarily this one) is the lack of a clearly pre-defined region of interest before scanning.  Sometimes (again, speaking generally, not about this paper) it looks as if a wide net has been cast in the hope of catching one or two fish, whatever size—fish that then make it into the Results section of a paper[4].

I’m also not so sure about these two groups of cognitive-affective styles.  I’d appreciate others’ views on this—have a look at the paper and tell us your thoughts.  I’m not a psychologist and I’ll admit I do not know the characteristics or the merits of the questionnaires these authors used.  However I’ve struggled to classify myself or any of my mates into one of these two groups.  I could easily be inward, outward, both or neither.   So, what’s my insula doing?

Flavia Di Pietro

Flavia Di Pietro is a PhD student in the Body and Mind Research Group, Sydney. She is investigating the development of Complex Regional Pain Syndrome (CRPS) after wrist fracture. Specifically, Flavia’s PhD involves brain scanning people who are in a higher than usual amount of pain in the first 3 weeks after the fracture, and then following them for a few months. Her question concerns whether or not there are changes in brain activation patterns that emerge before the CRPS does and if so, what do they tell us about the condition? More about Flavia here including her published research. BiM author’s downloadable PDFs can be found here.

References

[1] Kulkarni B, Bentley DE, Elliott R, Youell P, Watson A, Derbyshire SW, Frackowiak RS, Friston KJ, & Jones AK (2005). Attention to pain localization and unpleasantness discriminates the functions of the medial and lateral pain systems. The European journal of neuroscience, 21 (11), 3133-42 PMID: 15978022

[2] Singer T, Seymour B, O’Doherty J, Kaube H, Dolan RJ, & Frith CD (2004). Empathy for pain involves the affective but not sensory components of pain. Science, 303 (5661), 1157-62 PMID: 14976305

[3] Mazzola V, Latorre V, Petito A, Gentili N, Fazio L, et al. 2010 Affective Response to a Loved One’s Pain: Insula Activity as a Function of Individual Differences. PLoS ONE 5(12): e15268.

[4] Ioannidis JP (2011). Excess significance bias in the literature on brain volume abnormalities. Archives of general psychiatry, 68 (8), 773-80 PMID: 21464342