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Brain activity in unconscious patients offers new views of awareness

Using EEG and fMRI, researchers try to learn who is conscious but unable to respond

5:47pm, July 28, 2015
brain neworks

LOCKED IN  Patients in the left two images are outwardly in a vegetative state. But the neural connections, measured by electrical activity, are much more active in the middle patient, whose brain network more closely resembles a healthy volunteer’s (right). All three were asked to imagine themselves playing tennis.

The average brain weighs about 1.3 kilograms and consumes 20 percent of the body’s energy budget. Much of that energy powers the brain’s 86 billion nerve cells, or neurons, which conduct tiny electrical currents that can travel close to 120 meters per second. A typical neuron transmits its signals to about 7,000 neighboring cells and to cells beyond. These neurons assemble into structures responsible for specific tasks. But like individual chords in a symphony, their work blends in seamless harmony. Your visual cortex allows you to see these letters. Your motor cortex controls the movement of your hand to reach for the next page or scroll down the screen. Your prefrontal cortex helps assemble letters into words, words into sentences and sentences into meaning. All you know is that you’re reading.

None of these facts explain one of the greatest mysteries in biology: your conscious existence. The electrical and chemical chitchat among neurons somehow gives rise

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