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Shockingly Smart: The Physics Behind Brain Stimulation

There's been a lot of buzz lately about a therapeutic and augmentative procedure called tDCS, with promising results. tDCS may not only aid in the treatment of conditions such as depression and anxiety, but it also may be a quick, non-invasive way to improve focus, learn skills faster, and remember facts more easily while studying.

If you're wondering why you haven't heard of this miracle technology yet, it's because of what tDCS stands for: Trans-cranial Direct Current Stimulation. In layman terms, that's "putting electrodes on your head in hopes of shocking yourself smarter". At first blush, maybe it doesn't sound so appealing, but bear with me.

Image Credit: TZA via flickr | Rights Information

Dating all the way back to the 1800s, electrotherapy got its start with a man by the name of Giovanni Aldini. He was the nephew of Luigi Galvani, now remembered for being the first person in history who thought to poke a dead frog with "live" wires. When Galvani discovered that an electric current made the specimen's muscles contract little did he know that he had just kicked off a new era in philosophy and medicine with the twitch of a dead leg.

Aldini, carrying on his uncle's work and having already experimented with the electrocution of a dead human, wanted to find out for himself how the flow of a current might affect a conscious mind. Connecting electrodes to his ears, Aldini

"felt a strong shock, a sort of jolt against the inner surface of my skull. The effect increased further as I moved the electric arcs from one ear to the other. I felt a strong head stroke and I became insomniac for several days." [Source]

His experiment was a success, providing the first data pointing to the electrochemical nature of cognition, in the form of his temporary case of insomnia. Seeing the potential to improve lives, Aldini set about refining the procedure, eventually using it to treat a case of severe depression (at least temporarily; his reports don't include follow-up beyond a week after the treatment).

Since then, an increasing mastery of electromagnetism and neuroscience has allowed for more in-depth experimentation, with stunning results.  Modern-day tDCS uses much lower currents to improve memory and problem-solving skills, as well as mood and behavior.

Reportedly, the US military takes advantage of its neuroplasticity-increasing effects to train its snipers faster and better. But, given the intricacy and infinitesimal scale of the connections in our brains, how does something as seemingly simple as an extended shock to one part of the head produce such useful results?

Physics of the Brain

Contrary to the popular notion of the brain as an organic computer, the signals responsible for most behavior aren't transmitted purely by electricity. The motion of ions, atoms with either a deficit or surplus of electrons from their neutral state, is responsible for regulating the release of neurotransmitters, the "firing" of the neuron that leads to thought or sensation.

By applying a current in a certain direction, tDCS can effectively increase or decrease electrical polarization, affecting the chance that neurons in a given region of the brain will fire depending on the orientation of the subject's synapses and whether a positive or negative current is applied. The potential to decrease neuronal activity seems just as important as the potential to increase it by way of medical and psychiatric applications of the technology. Disorders like schizophrenia, for instance, seem to be linked to over-excitability in certain parts of the brain.

Not Your Typical Electroshock

While electrical interventions for psychiatric distress have gotten a bad reputation in modern culture thanks to unfavorable portrayals in films like One Flew Over the Cuckoo's Nest and A Beautiful Mind, the procedure depicted in those films (Electroconvulsive Therapy, or ECT) bears little resemblance to tDCS.

ECT, sometimes known as electroshock, is designed to induce seizures in the patient, using electric fields powerful enough to cause spontaneous and uncontrolled firing of neurons. The voltages involved in tDCS are low enough to produce effects entirely different from those seen in ECT. However, the potential for side-effects like respiratory depression makes home experimentation a potentially risky business.

In addition to acute safety concerns, some have expressed worries about the potential long term side-effects of "hacking" the brain like this, especially while long-term studies are still being conducted. Naturally, an easy-sounding way to supercharge the brain has attracted a large "DIY" community of futurists, eager to be part of the first generation of proto-cyborgs. But until protocols for proper device construction and safe electrode placement have been established, we have to stress that you probably shouldn't try this at home.


  1. ECT doesn't deserve its bad rep anymore -- modern methods have moved it beyond the Bell Jar days. It's my understanding that the physical effects have been minimized, and it's used with some anesthesia so there's no pain. In fact, it's even safe to use on pregnant women and elderly people.

  2. Also, did you see that a scientist accidentally tripped the brain's consciousness switch?

  3. ECT gives permanent brain damage. Any immediate effect is due to concussion. A temporary euphoria which fades after 4 - 6 weeks and the patient goes back to how they were plus they now have brain damage. People can forget their education and many years of their past life. They can have cognitive deficits and be unable to make new memories. Google Dr Peter Breggin

  4. tDCS is clinically available in Atlanta, Boston and New York for the treatment of depression and chronic pain. The Atlanta clinic provides training and supervision for home-use and cognitive enhancement.


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