The Singularity Is Nearer: When We Merge with AI

by Ray Kurzweil

So far there have been modest efforts to communicate with the brain using electronics, either inside or outside the skull. Noninvasive options face a fundamental trade-off between spatial and temporal resolution—that is, how precisely they can measure brain activity in space versus time. Functional magnetic resonance imaging scans (fMRIs) measure blood flow in the brain as a proxy for neural firing.[167] When a given part of the brain is more active, it consumes more glucose and oxygen, requiring an inflow of oxygenated blood. This can be detected down to a resolution of cubic “voxels” about 0.7 to 0.8 millimeters to a side—small enough to get very useful data.[168] Yet because there is a lag between actual brain activity and blood flow, the brain activity can often be measured to within only a couple of seconds—and can rarely be better than 400 to 800 milliseconds.[169] Electroencephalograms (EEGs) have the opposite problem. They detect the brain’s electrical activity directly, so they can pinpoint signals to within about one millisecond.[170] But because those signals are detected from the outside of the skull, it’s hard to pinpoint exactly where they came from, yielding a spatial resolution of six to eight cubic centimeters, which can sometimes be improved to one to three cubic centimeters.[171] The trade-off between spatial and temporal resolution in brain scans is one of the central challenges in neuroscience as of 2023. These limitations stem from the fundamental phy...