As scientists and doctors come ever close to installing computers in the human brain-and to replicating processes performed by the brain with computers-a specific field of neuroscience has become increasingly important: that of neuroimaging. The production of images of the brain can open up to our understanding the most secretive region of the body, allowing for new technologies that might revolutionize our lives by preventing disease, revealing new methods to treat brain injury, and even increasing the efficiency of our own cognitive processes. The idea behind neuroimaging is in fact a relatively simple one: the more we can see of how the brain's amazingly complex features work together, the better we can manage, manipulate, and even reproduce its functioning artificially.
Though it is a relatively specialized field, neuroimagining can be broken down into two separate fields: functional and structural neuroimagining. Structural neuroimagining is much older than functional neuroimaging, and in some ways easier to understand: a still image of the brain's structure is obtained using an array of devices including radio waves and x-rays, both developed in the beginning of the 20th century. As early as 1918, an American scientist imaged the ventricles of the brain by filling them with air and then applying modified x-ray technology. Technologies for structural neuroimaging diversified and became more complex later in the 20th century: in the 1970s, two other Americans were awarded the Nobel Prize for their development of computed axiol tomography, or CAT scans, which can be used to produce a still image by calculating the amount of x-rays absorbed by a pre-selected volume of brain tissue. Magnetic resonance imaging, or MRI, produces higher-detail structural images and uses magnets to align the nuclei of atoms in the body, generating a magnetic field which can be record and used to discern the shape of a chosen brain region.
By contrast with structural neuroimagining, functional neuroimaging seeks to capture a moving image of the brain as it processes information or carries out other tasks. Methods including positive electron tomography, or PET scans use sensors to track and record the movement of radioactive atoms as they circulate through the bloodstream into the brain (the atoms are injected into patients before the scan). As a result, scientists can see when certain neurological processes require that more blood move to certain areas of the brain, which is useful both for diagnosing damage and disease and for learning more about the way the healthy brain works. Even over the last five years, researches in neurobiology, cognitive science, and related fields have made massive advances using the insight made possibly by PET scans and related technologies like single photon emission computed tomography, or SPECT.
At present, the current standard for functional neuroimaging is functional magnetic resonance imaging, or fMRI. fMRI scans can be used to see inside any portion of the body; when focused on the brain, they can indicate not only which regions and structures of the brain are undergoing neuronal activation-that is, which parts of the brain are engaged at any given moment, during any given task-but also changes in neuronal activation in real time. Like PET scans, fMRI scans can be used for research purposes as well as for investigating damage or disease in single patients. Scientists have even managed to reverse engineer this process, making it possible to identify what a person is seeing or doing simply by watching moving images of blood flowing inside their brain. This is widely considered the closest human beings have ever come to successfully reading one another's minds. The scientific and medical applications for procedures of this last kind are truly staggering.