Last year, scientists from George Washington University published an amazing study arguing that they had found the “on-off switch” to the human brain, a veritable key to consciousness. The researchers found that when they stimulated a particular portion of the brain of a woman with epilepsy, she reliably slipped into a storing, near-catatonic state. When they removed the stimulation, she “awoke” and had no memory of the lapse in time. Called the “claustrum,” this area of the brain is poorly understood — but since the consciousness study, it has unsurprisingly attracted attention from brain researchers.
One study published this month in the journal Consciousness and Cognition may have constrained the realm of possibility for claustrum function, by conducting a study using combat veterans with deep traumatic brain injuries affecting the claustrum. What they found suggests that the prior results showing that stimulation of the claustrum can forcibly sever the brain from the conscious mind may have been due to the peculiarities of that patient, an epileptic who had undergone brain surgery in the past. In their combat veterans, who have a variety of other brain-related injuries in addition to their claustrum damage, the results were quite different.
They found that patients with claustrum lesions have an increased duration, but not frequency, of losing consciousness — showing that the claustrum may be related to regaining, but not ending, the state of active consciousness. That’s important, since the claustrum has been implicated in the maintenance of certain forms of coma and certain forms of dissociation.
The claustrum (technically the claustra, since there’s one per hemisphere) sits near the center of the brain and seems to have a large-scale coordinating function. It receives signals from virtually every portion of the neocortex, looking architecturally not all that unlike the corpus collosum, of A Scanner Darkly fame. In both cases, destruction can lead to truly odd and unsettling psychological effects — could stimulating one little patch of your brain really forcibly disengage the brain’s engine from its drive shaft, leaving a person coasting in an involuntary neutral gear?
As mentioned, the newest research seems to say that, thankfully, the claustrum might not offer that kind of off switch. Patients with permanently damaged brains can sometimes adapt to get lost function out of some other brain structure, however, so it’s possible that people will claustrum lesions (as opposed to reversible electrical stimulation) show different effects.
However, things are more complicated than that. There’s some evidence that the hallucinogenic drug known as salvia may work partially by affecting the claustrum — specifically, inhibition of the kappa-opioid receptors that are so common on its surface. Due to the impossibility of feeding college kids salvia in an ethics-approved study, the academic literature on this is based largely on the self-submitted trip-out reports on sites like Erowid.
If the claustrum does play some large-scale coordinating role in the brain, that could explain why salvia can cause the brain to interpret visual information in such bizarre ways — the parts of the brain that are good at visual tasks aren’t being properly engaged to actually do them. And it might also explain why it’s possible for someone with a damaged or inhibited claustum to receive visual information through the optic nerve, but not consciously see that visual information with the higher brain and snap back to reality.
Francis Crick (of Watson and Crick fame) spent much of his career pushing for continued study of the claustrum, which he believed was the seat of consciousness. We now know that’s not true — people can be quite conscious with their claustrum partially or entirely destroyed. But it may be to be one of the crucial elements in taking the many powerful but limited portions of the brain, and letting them complement each other’s abilities. It’s been called the conductor of the brain’s orchestra.
As scientists begin to understand these systems-level structures in the brain, our understanding of concepts like attention, memory, and perception could change dramatically. And with them, concepts like intention, self-awareness, and self.
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