杏吧原创

Perseverance in the face of adversity is an admirable character trait 鈥� now it turns out you can conjure it up with a quick zap to a tiny spot in the brain. The discovery in two people with epilepsy was accidental but it is the first to show that simple brain stimulation can create rich, complex alterations of consciousness.

, a neurologist at Stanford University in California, and his colleagues had implanted electrodes in the brains of two people with epilepsy to help identify the source of their seizures. In the course of their work, they noticed that an odd thing happened when they stimulated a region in the anterior midcingulate cortex 鈥� a part of the limbic system involved in emotion, processing, learning and memory. Both patients reported feeling a sense of foreboding, coupled with a determination to overcome whatever challenge they were about to face.

During the stimulation, one patient reported feeling 鈥渨orried that something bad is going to happen鈥� but also noted that 鈥渋t made me stronger鈥�. The other said he felt as if he were figuring out how to get through something.

He likened it to driving your car when one of the tires bursts. You鈥檙e only halfway to your destination and you have no option but to keep going forward. 鈥淵ou鈥檙e like鈥� am I gonna get through this?鈥� he said (see video). He also reported a sense of urgency: 鈥淚t was more of a positive thing like鈥� push harder, push harder, push harder to try and get through this.鈥�

One singular sensation

In contrast, when the researchers applied a sham stimulation 鈥� going through exactly the same procedure, but with the current set to zero 鈥� neither volunteer reported feeling any specific sensations. Stimulation of other nearby regions of the brain less than 5 millimetres away also failed to produce the feelings of either foreboding or perseverance.

The discovery may have implications for people with obsessive-compulsive disorder, which can be thought of as a disease of excessive perseverance. People with severe OCD are sometimes opt for surgery to the cingulate cortex, but not every person with the condition shows improvement. Surgeons might be able to improve their odds of success by identifying and targeting the exact part of the cingulate that produces feelings of perseverance, says Parvizi.

The study is also the first to show that simple brain stimulation can create rich, complex alterations of consciousness, says , a neurophilosopher at the University of California at San Diego. 鈥淚 was just bowled over by the implications for how we can start nailing down the circuitry underlying consciousness,鈥� she says.

Already, the result is a powerful argument against the claims by some philosophers that consciousness must involve something . 鈥淚f you can stimulate and get these complex effects, then stop the stimulation and the effects go away, it鈥檚 hard to see how you could maintain with a straight face the notion that consciousness is not a function of the brain,鈥� Churchland says.

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