Psychiatry Newsletter - To Sleep, Perchance to Diagnose
To Sleep, Perchance to Diagnose
Date: October 12, 2010
Team see new friend to psychiatry in REM sleep.
When Ebenezer Scrooge tried to explain away his ghostly visitors at night as “a bit of undigested cheese,” his idea wasn’t so far removed from one 20th century explanation of dreaming. Harvard’s Hobson and McCarley held that the dreams we experience are a byproduct of biology—not of digestion, of course, but rather the result of twitchings of the brainstem that provoke an intriguing response from the brain’s cortex as it tries to make sense of the random input.
But now, a new study by Psychiatry neuroscientist/ psychiatristCharles Hong and a mostly-Hopkins team offers evidence that may advance the field in what they and the earlier researchers think is a truer direction. The scientists are setting a platform for what may become a more purposeful biological rationale for dreams. The work suggests, for example, that the waking conscious mind and the dreaming one have far more in common than anyone suspected.
As exciting, says Hong, are the practical implications: “We believe our techniques could become a natural probe while people are asleep, a new way to simultaneously examine major brain systems—including those that go awry in psychiatric disease. This approach may clarify broadly what happens in patients with schizophrenia, depression or Alzheimer’s disease,” he explains, “or, one day, signal brain changes before symptoms appear.”
Basically—and this understates the difficulty—Hong’s team videotaped the rapid eye movements of healthy volunteers who spent the night asleep in an exquisitely sensitive functional MRI scanner. They then synchronized the results to get a real-time snapshot of active brain areas.
It wasn’t a stretch to expect that regions for eye movement would light up. And because Hong and earlier colleagues had revealed that, in REM sleep, eyes apparently track what they “see” in dreams, the Hopkins team also anticipated activity in some cortical areas for sight. That was indeed the case.
Yet there was more. Unexpected brain sites for hearing, smell, touch and balance are turned on when rapid eye movements occur in sleep, they found, as well as motor areas that control body movements. They’re likely the same areas active in awake, fully conscious people looking at and perceiving something.
“So, because so much is shared, we believe that consciousness in waking life and REM sleep dreaming are continuous,” says colleagueJames Harris (Q&A below). It’s just that the nature of consciousness differs somewhat in each: “During waking consciousness you’re seeing things in the real world. In dream consciousness, you’re also looking at images, but, it appears, they’re created internally by your brain,” Harris explains.
Now for the practical: Hong says many of the brain regions shown active under fMRI function poorly in psychiatric disease. Both language areas and the basal nucleus, for example, are profoundly affected in Alzheimer’s disease—areas apparently active in eye-movement sleep. Other REM-active regions—for sensory processing, for example—go awry in schizophrenia.
Additionally, Hong’s team found that a dense serotonin-secreting neural network has lowered activity in healthy dreaming subjects’ brains. Having a window into the workings of serotonin, a molecule closely tied to mood and to mood disorder therapy, could be a great benefit, he says.
The plan, Hong explains, would be to compare healthy people at sleep with those touched by psychiatric disorders or even with their apparently healthy family members. “An advantage is that they’re all asleep, all having rapid eye movements, probably scanning their dreams. So you can carry out accurate studies in uncooperative schizophrenia patients, in infants, or those with Parkinsonian tremors, which abate during sleep.” Much work lies ahead, Harris adds, “but the potential has us excited.”
The research team included scientists at Kennedy Krieger Institute’s F.M. Kirby Research Center. An account is published online in November’sHuman Brain Mapping.
For info: e-mail Charles Hong at firstname.lastname@example.org