Neuroscience
Alert to your surroundings but helpless to respond. It's difficult to imagine a worse situation, but this is the terrifying reality for a minority of brain damaged patients with total locked-in syndrome. Fortunately, researchers are developing ways to reveal consciousness trapped inside a lifeless body. Such techniques will hopefully prevent conscious, yet utterly paralysed, patients from being misdiagnosed as comatose.
In this new study, Caroline Schnakers used bed-side electroencephalography (EEG) to detect consciousness in a 21-year-old woman who fell into a coma-like state following a stroke. Twenty-five, 39 and 49 days after her brain was damaged, the researchers uttered the woman's own name to her, together with a short list of irrelevant names, all the while recording the surface electrical activity of her brain with EEG. The important twist was that they sometimes instructed her to pay special attention to her own name, or to one of the unfamiliar names.
During the first two testing sessions, the woman's brain recordings betrayed no signs of awareness. On the third session, however, when she was instructed to pay special attention to her own name, the woman's EEG signal showed an exaggerated P300 response to her name, compared with when she was instructed to just listen passively. The P300 is a spike of activity recorded from the parietal lobe, which is thought to be a marker of consciousness or decision making. This suggests the woman had heard and heeded the task instruction - a sign that she was conscious inside her paralysed body. Fourteen days later, she began to show behavioural signs of awareness, for example by moving her finger in response to instructions.
The researchers said: "In conclusion, this active auditory event-related paradigm (requiring explicit comprehension of auditory-verbal instructions) provides an interesting tool for detecting voluntary brain activity in patients that behaviourally would be diagnosed as comatose". More research is now needed to validate this procedure, they added.
The new case-study comes after research published in 2006 that used functional brain imaging to detect consciousness in a patient in a persistent vegetative state. The EEG used in the current study has the advantage that it can be administered bed-side.
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Schnakers, C., Perrin, F., Schabus, M., Hustinx, R., Majerus, S., Moonen, G., Boly, M., Vanhaudenhuyse, A., Bruno, M., & Laureys, S. (2009). Detecting consciousness in a total locked-in syndrome: An active event-related paradigm. Neurocase, 15 (4), 271-277 DOI: 10.1080/13554790902724904
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
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Neuroscience
Detecting consciousness in a totally locked-in patient
Alert to your surroundings but helpless to respond. It's difficult to imagine a worse situation, but this is the terrifying reality for a minority of brain damaged patients with total locked-in syndrome. Fortunately, researchers are developing ways to reveal consciousness trapped inside a lifeless body. Such techniques will hopefully prevent conscious, yet utterly paralysed, patients from being misdiagnosed as comatose.In this new study, Caroline Schnakers used bed-side electroencephalography (EEG) to detect consciousness in a 21-year-old woman who fell into a coma-like state following a stroke. Twenty-five, 39 and 49 days after her brain was damaged, the researchers uttered the woman's own name to her, together with a short list of irrelevant names, all the while recording the surface electrical activity of her brain with EEG. The important twist was that they sometimes instructed her to pay special attention to her own name, or to one of the unfamiliar names.
During the first two testing sessions, the woman's brain recordings betrayed no signs of awareness. On the third session, however, when she was instructed to pay special attention to her own name, the woman's EEG signal showed an exaggerated P300 response to her name, compared with when she was instructed to just listen passively. The P300 is a spike of activity recorded from the parietal lobe, which is thought to be a marker of consciousness or decision making. This suggests the woman had heard and heeded the task instruction - a sign that she was conscious inside her paralysed body. Fourteen days later, she began to show behavioural signs of awareness, for example by moving her finger in response to instructions.
The researchers said: "In conclusion, this active auditory event-related paradigm (requiring explicit comprehension of auditory-verbal instructions) provides an interesting tool for detecting voluntary brain activity in patients that behaviourally would be diagnosed as comatose". More research is now needed to validate this procedure, they added.
The new case-study comes after research published in 2006 that used functional brain imaging to detect consciousness in a patient in a persistent vegetative state. The EEG used in the current study has the advantage that it can be administered bed-side.
_________________________________
Schnakers, C., Perrin, F., Schabus, M., Hustinx, R., Majerus, S., Moonen, G., Boly, M., Vanhaudenhuyse, A., Bruno, M., & Laureys, S. (2009). Detecting consciousness in a total locked-in syndrome: An active event-related paradigm. Neurocase, 15 (4), 271-277 DOI: 10.1080/13554790902724904Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
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The 54-year-old epilepsy patient - her name remains concealed to protect her privacy - was lying on the operating table while surgeons explored inside her brain with electrodes. They were looking for the source of her epileptic seizures. Suddenly, after...
- Inside The Brain Of A Woman With Conversion Paralysis
A new brain imaging study shows the difference, in terms of brain activity, between a person feigning having a paralysed arm and a patient with conversion paralysis - that is, paralysis with no clinically identifiable neurological cause. Conversion paralysis...
- The Precuneus And Recovery From A Minimally Conscious State
You've probably heard about the case of Terry Wallis, a 42 year old man in Arkansas who spent 19 years in a "minimally conscious state" following severe traumatic brain injury. Then one day he saw his mother walk into the room and (after not speaking...
- News In Science - Woman In Coma Plays Tennis - 08/09/2006
News in Science - Woman in coma plays tennis - 08/09/2006: "Brain scans of a woman who has been in a vegetative state for five months show her imagining playing tennis and responding to commands, researchers report..." The big question is whether or not...
- Signs Of Consciousness
Jerome Groopman has an article in the Oct. 15 issue of the New Yorker. Medical Dispatch: Silent Minds: Reporting & Essays is about consciousness, particularly among those in various degrees of coma. Groopman reports on some fascinating work by the...