Empty mind — a brain disorder?

A French neurological team has described a surprising new brain disorder — a deficit of spontaneous conscious thinking. LaPlane and Dubois describe it as “auto-activation deficit.” (*) People with this problem lose spontaneous conscious feelings, thought and actions — until they are asked to do something. Then they act perfectly well.

Maybe it should be called Standby Disorder The neurologists write, “They tend to stay in the same place all day long, sitting on a chair or lying on their bed, taking no initiatives and asking no questions, although they answer questions appropriately. They do not move around or engage in spontaneous activity.” But “the most enigmatic symptom encountered in these patients is mental emptiness. Their mind is ‘empty, a total blank,’ they say. In most typical cases, they have no thoughts and no projections for the future.”

For example:

• An active businessman became dramatically inactive when stung by a wasp. Brain damage developed (perhaps due to an allergic reaction). “He did almost nothing all day long and expressed no sign of interest in anybody. Later he became capable of buying a newspaper, reading it quickly, and watching TV, but he remained inactive most of the time. When stimulated, however, he was able to perform more complex activities, such as playing high level bridge. He was not bored by his condition, but it surprised him.”
• Another patient “stayed in bed for half an hour with an unlit cigarette in his mouth. When asked what he was doing, he responded, ‘I am waiting for a light.’”
• A third victim “spent 45 minutes with his hands on a lawn mower, totally unable to initiate the act of mowing. This blockage disappeared instantaneously when his son told him to move.”

“In conclusion,” the authors say, “it might be said that the mind of patients is on stand-by when they are alone, but recovers almost all of its capabilities when stimulated by social interactions.”

Maybe it should be called Standby Disorder, as if the mind is on stand-by, idling — ready to go but with no impulse to do anything, think anything, or feel anything.

What is going on?

Such tragic cases can help us learn about consciousness.

LaPlane and Dubois are careful to point out that auto-activation deficit (or AAD) does not affect movement as such. Patients move perfectly well when asked to do so. They show no signs of coma or drowsiness. They even seem to keep the same level of intelligence as before, as in the case of the businessman who could “play high-level bridge.” The emotions of AAD victims are appropriate when they hear good news or bad. But their emotions are short-lived, and they quickly go back to their neutral state.

Normally, when people have deficits in conscious contents, we would expect damage in cortex. These patients show no such damage. Or if people are in coma, we would expect damage in the brainstem. Again, no such injuries are seen in AAD. Rather, LaPlane and Dubois have found, the problem is in the basal ganglia. Brain imaging studies show injury to an area of the basal ganglia called the pallidum.

Why the basal ganglia? Usually we think of this part of the brain as having to do with automatic action components. For example, you are conscious of this sentence right now, but your eye movements are not conscious — they are automatic. You have had so much practice reading that there is no need for conscious control. Such automatic action elements use the basal ganglia, deep inside the brain.

But if this part of the brain involves automatic, unconscious activities, how could it affect consciousness? After all, conscious contents are handled in cortex, not the basal ganglia. The answer is that there is a circuit between the basal ganglia, the thalamus (the gateway to cortex), and the prefrontal cortex (which handles goals, motor plans, working memory, and much more). The remarkable symptoms of AAD may reflect a disruption of this “striato-thalamic-prefrontal loop.”

Such tragic cases can help us learn about consciousness It is as if major city were paralyzed by blocking a large traffic artery. Nothing may be wrong in the city itself. It is simply not receiving what it needs to keep going.

The endless activity of the conscious mind was already explored in the Upanishads, 2600 years ago. Meditation techniques were devised to calm the mind, to stop it from constantly buzzing with thoughts. The endless activity of the conscious brain can even make it hard to get a good night’s sleep.

But humans with AAD have too much peace of mind. They are frozen in an eternal calm, unable to think or act on their own.

Review by Bernard J. Baars (© 2002)

References

1. Dubois Homepage
2. Laplane, D. & Dubois, B. (2001) Auto-activation deficit: A basal ganglia related syndrome. Movement Disorders, 16 (5), 810-814.