The People Whose Minds Are Completely Blank
One day, a lively and successful businessman was bitten by a wasp, triggering an unexpected encephalopathy of the brain. Afterwards, he was a changed man, doing almost nothing all day and expressing little interest in anyone else. But this apathy could be swiftly reversed with even the tiniest stimulation from another human being – offering a newspaper or challenging him to a game of bridge, for example. It's as if the man could react, but not act.
Cases similar to this one have been documented in the medical literature. There was a patient who at one point laid on his bed for thirty minutes with an unlit cigarette in his mouth. When asked what he was doing, he matter-of-factly responded, "I am waiting for a light". Another person spent 45 minutes standing with his hands on a lawn mower, frozen and unable to move. But when prompted by his son to cut the grass, he immediately sprang into action. A man referred to as Mr. M in a case report required external prodding for all of his daily activities, even eating. On one occasion he almost got burned by staying too long in the shower until he was told to turn the water off.
The syndrome striking these people is called Auto-Activation Deficit (AAD). First characterized by French researchers back in 1984, it seems to be caused by damage to the basal ganglia, which in turn disrupts fibers which control the activation of mental processing. The basal ganglia constitute numerous structures found near the base of the brain. Collectively, they are best known for their role in triggering wanted movements while inhibiting unwanted movements.
"Patients with AAD do not try, or do not want to move, but they can move without difficulty when incited to do so," researchers at INSERM wrote in 2001. "It might be said that the mind of patients with AAD is on stand-by when they are alone, but recovers almost all of its capabilities when stimulated by social interactions."
But some patients with AAD experience an even more curious symptom: they cannot think.
"Their mind is 'empty, a total blank,' they say. In the most typical cases, they have no thoughts and no projections in the future," the researchers wrote.
"Patients with AAD remain with an empty mind while in the waking state. They describe a mental state, that, to our knowledge, has never been reported, and which is almost unimaginable to a normal conscious human being: conscious awareness without any content."
Strangely, however, some AAD patients with this mental blankness are able to dream, though their dreams are shorter, simpler, and seemingly devoid of emotion. The French scientists who made this discovery said it suggests that basic dreams are generated by brainstem stimulation, but full dreaming with stories, social interactions, and emotion require the involvement of higher-order cortical areas, like the basal ganglia.
Fortunately for patients with AAD, it's growing increasingly clear that dopamine agonists, drugs which imitate the actions of the neurotransmitter dopamine, can effectively treat the condition in most instances. People with the disorder are no longer doomed to paralyzing apathy and numbing mental blankness.