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Some patients with severe brain damage may be more aware than we think, according to the first study to assess their brain activity with imaging technology. Minds of minimally conscious patients appear to retain the ability to process language. The results are “a new voice for these patients,” says Columbia University professor Joy Hirsch, one author of the multi-institutional study.
A minimally conscious patient will occasionally respond to commands, reach for objects or make other purposeful gestures. In contrast, patients in a vegetative state show no such behavior; this was the case for Terri Schiavo, the Florida woman whose plight gained national attention in March. Hirsch and her colleagues compared functional magnetic resonance images of two minimally conscious patients with those of seven healthy subjects, taken as the individuals listened to recordings by loved ones about past experiences they had shared. The injured brains showed activity in the language centers of the temporal lobes that was strikingly similar to that in the healthy brains. But when the researchers played the narratives backward, the injured brains’ response was far inferior, perhaps indicating an inability to fully tap into their neural circuitry.
The possibility that minimally conscious patients could be tuned in to activity around them—such as bedside conversations among doctors and family members—without being able to respond underscores the limitations of current tests used to estimate consciousness, the researchers say. Additionally, having the “infrastructure for cognition in place suggests that it is at least theoretically possible” for these patients to regain some functions and perhaps return to a preinjury state, Hirsch notes. She and her co-workers continue to investigate how imaging might assess cognition and whether it can predict recovery.