Extensive Brain Activity During Listening To Speech Found In Minimally Conscious Patients

“The results challenge our thinking about the possible inner lives these patients may experience, and also motivate renewed interest in research aimed at recovery and rehabilitation,” said the study’s senior author, Joy Hirsch, Ph.D., professor of neuroradiology and psychology and director of the fMRI Research Center at Columbia University Medical Center. “Brain imaging can be thought of as giving a voice to minimally conscious patients and allows us as physicians and scientists to be more aware about the patient’s potential for rehabilitation.”

Patients in minimally conscious states can open their eyes and move their arms about, similar to patients who are in a persistent vegetative state. However, minimally conscious patients can sometimes demonstrate that they are aware of themselves or their environment. They can occasionally say words, follow commands such as “move your eyes to the left,” and respond to questions about their emotions. At other times they are unresponsive.

In the present study, the researchers used functional magnetic resonance imaging (fMRI) to look at the brain activity of two minimally conscious patients. One, 21, had experienced a sudden brain hemorrhage; the second, 33, suffered a blunt head trauma.

While the patients were in the imaging machines, they listened to audio recordings made by a family member reminiscing about weddings, birthdays, or other experiences shared by the two. The same procedure was repeated with seven healthy and fully conscious subjects.

“Our hypothesis was that these patients would show neurocircuitry that was only partially intact. In other words, if five regions of the brain are needed for understanding speech, only three would be present,” said Dr. Hirsch. “What we saw surprised us. It was a very haunting finding. Both patients, though one more than the other, had patterns of brain activity that were indistinguishable from the normal subjects while they were listening to spoken narratives.”

In the second patient, even the visual area of the brain lit up during the audio playback, though the patient had his eyes closed. “We speculate, although we don’t know for sure, that the audio conjured up images in the patient’s mind,” said Dr. Hirsch. “It looks to us that, in at least some minimally conscious patients, the brain’s circuitry may still be intact, and that’s very encouraging,” Dr. Hirsch says. “It’s possible that these patients could benefit from therapeutic interventions and there are now a number of trials on the horizon.”

The findings were published in the Feb. 8th issue of Neurology.

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