Sunday, March 05, 2006

Humor, Hot Flashes, and Empathy for Pain

These three phenomena activate the same brain areas (anterior cingulate cortex and frontoinsular cortex), according to recent findings. Any theory about the neural correlates of empathy must take into account the fact that the same brain regions are activated during menopausal hot flashes and the appreciation of humor.

Freedman RR, Benton MD, Genik RJ 2nd, Graydon FX.
Cortical activation during menopausal hot flashes.
Fertil Steril. 2006 Mar;85(3):674-8.

OBJECTIVE: To determine regions of brain activation associated with menopausal hot flashes and sweating. DESIGN: Controlled laboratory study. SETTING: University medical center. PATIENT(S): Symptomatic postmenopausal women and asymptomatic eumenorrheic women. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Brain activation measured by functional magnetic resonance imaging. RESULT(S): Significant (P<.001) areas of activation during hot flashes in symptomatic women included the insula and anterior cingulate cortex. Sweating in the eumenorrheic women was associated (P<.001) with activity in the anterior cingulate and superior frontal gyrus. CONCLUSION(S): Activation of the insular cortex is associated with the "rush of heat" described during menopausal hot flashes. Thermoregulation in humans appears to be represented in a distributed cortico-subcortical network rather than in a single localized structure.

Watson KK, Matthews BJ, Allman JM.
Brain Activation during Sight Gags and Language-Dependent Humor.
Cereb Cortex. 2006 Mar 2; [Epub ahead of print]

Humor is a hallmark of human discourse. People use it to relieve stress and to facilitate social bonding, as well as for pure enjoyment in the absence of any apparent adaptive value. Although recent studies have revealed that humor acts as an intrinsic reward, which explains why people actively seek to experience and create humor, few have addressed the cognitive aspects of humor. We used event-related functional magnetic resonance imaging to differentiate brain activity induced by the hedonic similarities and cognitive differences inherent in 2 kinds of humor: visual humor (sight gags) and language-based humor. Our findings indicate that the brain networks recruited during a humorous experience differ according to the type of humor being processed, with high-level visual areas activated during visual humor and classic language areas activated during language-dependent humor. Our results additionally highlight a common network activated by both types of humor that includes the amygdalar and midbrain regions, which presumably reflect the euphoric component of humor. Furthermore, we found that humor activates anterior cingulate cortex and frontoinsular cortex, 2 regions in the brain that are known to have phylogenetically recent neuronal circuitry. These results suggest that humor may have coevolved with another cognitive specialization of the great apes and humans: the ability to navigate through a shifting and complex social space.

Saarela MV, Hlushchuk Y, Williams AC, Schurmann M, Kalso E, Hari R.
The Compassionate Brain: Humans Detect Intensity of Pain from Another's Face.
Cereb Cortex. 2006 Feb 22; [Epub ahead of print]

Understanding another person's experience draws on "mirroring systems," brain circuitries shared by the subject's own actions/feelings and by similar states observed in others. Lately, also the experience of pain has been shown to activate partly the same brain areas in the subjects' own and in the observer's brain. Recent studies show remarkable overlap between brain areas activated when a subject undergoes painful sensory stimulation and when he/she observes others suffering from pain. Using functional magnetic resonance imaging, we show that not only the presence of pain but also the intensity of the observed pain is encoded in the observer's brain--as occurs during the observer's own pain experience. When subjects observed pain from the faces of chronic pain patients, activations in bilateral anterior insula (AI), left anterior cingulate cortex, and left inferior parietal lobe in the observer's brain correlated with their estimates of the intensity of observed pain. Furthermore, the strengths of activation in the left AI and left inferior frontal gyrus during observation of intensified pain correlated with subjects' self-rated empathy. These findings imply that the intersubjective representation of pain in the human brain is more detailed than has been previously thought.

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At March 05, 2006 1:05 PM, Anonymous Anonymous said...

Cognitive neuroscientists want to identify neural correlates of X, where X is some ability or mental state that humans care about (say, emapthy).

The neuroscritic implies that it is problematic to find that some of the neural correlates of X are the same as the neural correlates of a seemingly unrelated ability/state Y. Why?

At March 07, 2006 4:35 PM, Blogger The Neurocritic said...

It could be that the neural correlates of humor, hot flashes, and empathy are all the same. This would not be a problem for some cartographers of cognition (and emotion) who don't really care about phenomenology (i.e., laughing at a joke *seems* to be a different experience than "feeling someone else's pain" or having a hot flash, but some circuit in the brain can't distinguish between these least at the crude level of analysis permitted by fMRI).

OR it could be that the similarly-located BOLD activations observed in fMRI studies of humor, hot flashes, and empathy are driven by some underlying commonality (let's say an increase in autonomic functions such as heart rate, blood pressure, and sweating). There is some evidence that the brain areas mentioned above are, in fact, sensitive to increases in arousal and autonomic activation (see the post "More Lies... Damn Lies..."). If the degree of activation in the anterior cingulate cortex and frontoinsular cortex are correlated with autonomic activation, one would of course expect hot flashes to be the worst [NOTE: the scanner environment would preclude humor that induces guffawing and belly-laughing]. Anyway, one would need to test peri-menopausal women on humor and empathy for that comparison...


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