For the first time, researchers have been able to switch off consciousness in a woman by electrically stimulating a single brain area. The discovery suggests that a single area – the claustrum – might be integral to combining disparate brain activity into a seamless package of thoughts, sensations and emotions.
Mohamad Koubeissi at the George Washington University in Washington DC and his colleagues said they managed to switch a woman’s consciousness off and on by stimulating her claustrum – a thin, sheet-like structure that lies hidden deep inside the brain.
Scientists were conducting experiments on a woman who had history severe epileptic seizures. When an electrode inserted in her brain near the area called claustrum was stimulated, the woman immediately stopped movement, talk and started staring into emptiness, as reported by a detailed paper in “Epilepsy and Behaviour” journal.
As soon as the stimulation stopped, she immediately regained consciousness with no memory of the event. The same thing happened every time the area was stimulated during two days of experiments. If the stimulation was disrupting a brain region responsible for movement or language she would have stopped moving or talking almost immediately. Instead, she gradually spoke more quietly or moved less and less until she drifted into unconsciousness. Since there was no sign of epileptic brain activity during or after the stimulation, the team is sure that it wasn’t a side effect of a seizure.
Koubeissi said that the results do indeed suggest that the claustrum plays a vital role in triggering conscious experience.