Shadows of Thoughts Revealed

Abstract

W hat do thoughts look like in the human brain? Does every mental sentence, every intention, every little decision explode in a telltale pattern of neurochemical activity? If so, might a brain scan someday provide a printout of a person's most intimate thoughts? As of 1990, neither scientists nor philosophers have gained sufficient insight into the nature of cognition to peruse the private diaries nestled within the brain's convoluted folds. But researchers using new technology have now developed the first pictures of what they call shadows of Their approach can't detect the contents of thoughts. However, it clearly differentiates among many of the electrochemical fireworks that underlie specific acts of cognition. The technique's developers say the high-resolution images they obtain may soon provide a wealth of practical benefits ranging from improved assessment of brain injury to reduced incidence of fatigue-related industrial accidents. Moreover, the work offers intriguing new clues about how the brain perceives and constantly updates its sense of the world and its sense of self. Generations of neuroscientists have dreamed about having a movie camera for observing thinking in the says Alan Gevins, director of EEG Systems Laboratory, a private brain-research center in San Francisco. Revolutionary advances in computers are now making this possible. A space-age electroencephalography (EEG) device, worn like a soft helmet, is the heart of Gevins' mind-camera. Unlike old-fashioned EEG machines, which record electrical signals at 19 points on the scalp and enable clinicians to detect gross brain-wave abnormalities, Gevins' device records electrical activity at 124 points. Computers monitor the skullbound electrical squalls we call thought and map their shifting locations within a three-dimensional image of the monitored brain, created by a magnetic resonance imager (MRI). The EEG-MRI combo -called the mental activity network scanner, or MANSCAN snaps a fresh picture of brain activity every 4 milliseconds, providing far more images per minute than positron emission tomography (PET), another popular brain-imaging technique (SN: 2/25/89, p.116). Together, the string of snapshots provides a movie of neuronal bursts, tracing peaks and troughs of brain activity while the monitored person performs specific mental tasks. Speaking in St. Louis last week at the *~ :