Harvard Medicine

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Misguided by Voices

Auditory hallucinations light up the brain.

© Chris Schmidt/iStockphoto.com

For weeks now, she’d been feeling that things weren’t quite right. Nothing she could put her finger on, just a low-grade suspicion that everyone around her was merely trying to act natural. When her doctor scheduled routine blood work, she could barely quell the nausea of foreboding. And when the clinic’s seemingly harmless phlebotomy tech asked her to make a fist so he could prod her forearm for a vein, the queasy dread in her stomach bloomed.

Then she heard them—a fluttering of voices, hushed, secretive, drifting from the air vent in the ceiling.

“We should do it now,” one of the voices whispered.

“Yes,” hissed another. “She’s right here. Let’s do it.”

The tech turned, syringe in hand, and suddenly her qualms made sense: She was at the center of an elaborate medical experiment. And everyone in the clinic was in on it.

She bolted.

This woman’s experience typifies what people—usually those suffering from schizophrenia—report when describing auditory hallucinations. Such people can pinpoint where the voices are coming from and whether they sound male or female. The voices are always hostile.

Yet according to Dost Öngür, an HMS assistant professor in psychiatry at McLean Hospital, just because it’s a hallucination doesn’t mean it’s a delusion
“These patients actually hear something,” he explains. “They don’t just imagine voices; their auditory circuits are fully engaged. All that’s missing is the external stimulus.”

Brain scans confirm this statement. David Silbersweig, chair of the Department of Psychiatry at Brigham and Women’s Hospital, and others have found that when patients experience auditory hallucinations, their primary auditory cortex, the region of the brain that receives direct input from the ears, is fully activated. Yet the brain’s anterior cingulate cortex, which differentiates between external and internal stimuli, loses its ability to make that distinction. In fact, postmortem analyses of patients often show cellular abnormalities in that very brain region.

“It’s a twofold mechanism,” says Öngür, who conducts brain imaging studies as part of his work as clinical director of McLean’s Schizophrenia and Bipolar Disorder Program. Öngür adds that the origins of auditory hallucinations are unclear. Very likely, abnormalities occur in the brain during key moments of early development, and these abnormalities make it difficult for patients to meet the demands of daily life, ultimately leading to symptoms. For now, clinicians can treat those symptoms with drugs that regulate dopamine activity, but such treatments don’t address the source.

“I wish we knew what caused these hallucinations,” Öngür says. “I’m hopeful that our research will soon provide more clues.”

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