Severed From Emotion

By June Kinoshita|Wednesday, July 01, 1992
Ethan seemed like just another one of those slightly dotty people who lack the common sense to get through life. His habitual tardiness got him fired from job after job, yet he couldn’t see the consequences of his actions. While he let an unsavory business associate talk him out of his life savings, no one could talk him out of marrying a woman of ill repute.

None of this would have been remarkable were it not for the jarring contrast it presented to Ethan’s past life. He had been a successful accountant, a family man, and a civic leader. Then in 1975, when he was 35, a benign tumor was excised from the front of his brain. When he recovered, he was a changed man. He could no longer hold a job. He divorced his wife and took up with a prostitute. Within two years Ethan lost his home, his family, and all his money.

Over the next decade a battery of tests showed that his IQ and reasoning abilities were well above average. He remained an accounting whiz. He could chat knowledgeably about politics and the economy. He knew what had happened to him, yet he seemed quite unperturbed. Psychiatrists were unable to find signs of organic brain dysfunction.

In desperation, Ethan’s brother turned to neurologist Antonio Damasio at the University of Iowa College of Medicine to find out whether the brain operation could have caused such disastrous behavior. By this time the technique of magnetic resonance imaging was making available previously impossible images of the brain’s interior. Damasio found that the operation had claimed the ventromedial region of the frontal cortex-- roughly between the eyebrows, deep in the crevice between the two cerebral hemispheres.

This region is known to do at least two things. It receives sensory information that lets us perceive the outside world, and it communicates with the autonomic nervous system centers--brain regions that regulate such bodily states as heart rate, breathing rate, blood pressure, and sweating. These responses, which are generally outside our conscious control, form the physical basis for our emotional states, from pleasure to alarm.

The ventromedial region, Damasio and his team of researchers observed, seems to link knowledge about the outside world to these inner states. Perhaps, they theorized, the region responds to information about the world by activating pleasant or unpleasant feelings associated with similar perceptions in the past. As we grow up, says Damasio, we learn to connect the outcomes of our conduct with certain ways of feeling--good if the results are rewarding, bad if they’re negative. These feelings, fine-tuned over the years, might help us decide how to act in a complex social situation. Ethan’s poor judgment, Damasio suspected, might be traced to their absence.

To test the theory, the investigators examined Ethan’s autonomic responses to socially loaded stimuli. By recording his skin’s electrical conductance (sweaty skin conducts electricity more efficiently), they monitored his reaction to a series of slides. Most depicted bland landscapes or abstract patterns, but interspersed were violent or pornographic images that sent normal people’s skin conductance hopping. Recordings from Ethan’s skin showed no response. I couldn’t believe they were so flat, recalls Daniel Tranel, one of Damasio’s co-workers. The visual cues in these slides make normal people wince. Loaded auditory cues resulted in the same nonresponse. Ethan reacted to a tape of heavy moaning no differently than he did to a tape of chirping birds.

If Damasio is right, we may have to revise our ideas about what guides our social conduct. Perhaps it is not just conscious reasoning but a subconscious frisson that prevents most of us from buying stolen radios or running off with our best friend’s spouse. People like Ethan who are cut off from their visceral feelings may thus be bereft of crucial markers that influence normal behavior. This acquired sociopathy, Damasio believes, may be more common than is recognized. The ventromedial region is one of the sites most liable to damage in head injuries sustained in car accidents. There may be a lot of people with brain dysfunctions, says Tranel, who get into trouble for reasons they can’t help.
Comment on this article
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

ADVERTISEMENT
ADVERTISEMENT
Collapse bottom bar
DSC-JanFeb15
+

Log in to your account

X
Email address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it emailed to you.

Not registered yet?

Register now for FREE. It takes only a few seconds to complete. Register now »