Infographic 2.1: Ways to Study the Living Brain

The introduction reads, “In the past, scientists were limited in their ability to study the brain. Most of what they learned came from performing surgeries, often on cadavers. Today, imaging and recording technologies enable us to investigate the structure and function of the living brain. CAT and MRI techniques provide static pictures of brain structures, while functional imaging and recording techniques allow us to see the relationship between brain activity and specific mental functions. Functional techniques can also be used to diagnose injuries and diseases earlier than techniques that look at structure. New technologies are continually being developed, allowing us to study the brain in ways we couldn’t imagine just a few years ago.” The frame at the left is titled, “Looking at Brain STRUCTURE,” and contains two sections. The first section is labeled “COMPUTERIZED AXIAL TOMOGRAPHY—CAT,” and shows a grayscale image of a brain cross-section with the brain in gray and the surrounding skull in white. The text reads, “Using X-rays, a scanner creates multiple cross-sectional images of the brain. Here, we see the brain from the top at the level of the ventricles, which form the butterfly-shaped dark spaces in the center.” The second section is titled, “MAGNETIC RESONANCE IMAGING—MRI,” and shows a grayscale image of a scan showing the dark rippled edges of the brain against the white skull. Another image shows a person on a table with his upper body inside the huge, white MRI scanner. The text reads, “An MRI machine’s powerful magnets create a magnetic field that passes through the brain. A computer analyzes the electromagnetic response, creating cross-sectional images similar to those produced by CAT, but with superior detail.” The frame at the right is titled, “Watching Brain FUNCTION,” and contains three sections. The first section is titled, “EEG—ELECTROENCEPHALOGRAM,” and shows one image displaying electrical activity on a monitor, and one image of a woman with many small electrodes attached to her head. The text reads, “Electrodes placed on the scalp record electrical activity from the cortical area directly below. When the recorded traces are lined up, as in the computer readout seen here, we can see the scope of functional responses across the lobes.” The second section is titled, “PET—POSITRON EMISSION TOMOGRAPHY,” and shows an image of a syringe and needle and an image of a multicolored brain scan slide. The text reads, “A radioactively labeled substance called a tracer is injected into the bloodstream and tracked while the participant performs a task. A computer then creates 3-D images showing degrees of brain activity. Areas with the most activity appear in red.” The third section is titled, “fMRI—FUNCTIONAL MAGNETIC RESONANCE IMAGING,” and shows an image of a brain scan. The scan is medium to dark gray, with two blue dots toward the upper part of the image, and one yellow L-shaped patch at the bottom right. The text reads, “The flow of oxygen-rich blood increases to areas of the brain that are active during a task. fMRI uses powerful magnets to track changes in blood-oxygen levels. Like PET, this produces measurements of activity throughout the brain.” The bottom left frame is titled, “What’s Next? Making Connections.” An image shows a multi-colored, feathery brain shape against a black background. The text reads, “The intricate pathways of myelinated axons in the brain can’t be seen in the imaging techniques shown here. But new technologies like diffusion spectrum imaging (DSI), which tracks the diffusion of water molecules through brain tissue, are being used to map neural connections. The resulting images show a complex information superhighway, with different colors indicating directions of travel.