Research Advances > Brain Imaging > How brains are imaged

How brains are imaged

What can be measured in a brain?

Researchers measure four different components in human brain studies:

  1. The volumes and positions of the different brain areas.
  2. The interconnections between different brain areas.
  3. The activity of a particular brain area.
  4. The chemical composition of a brain area.

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1. Measuring volumes and positions of different brain areas

If you were asked to find differences in the brain of a person diagnosed with ASD, probably your first approach would be to look at brains and see whether there are any differences between an individual with ASD and a neurotypical person. Although this can be done after a person dies, it is more common to do this while the person is still alive. The workhorse for this approach has been a technique called magnetic resonance imaging (MRI).1

Click here to learn about an MRI.

2. Measuring interconnections between different brain areas
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In the early 1990s, some researchers found a way to slightly modify the MRI technique to measure connections between areas.2 This modified technique is called diffusion tensor imaging (DTI). The number of studies using this technique is growing rapidly, and we are now at the beginning of an era of connectivity studies in the human brain.

Click here to learn how DTI works.

3. Measuring the activity of a particular brain area

Neurons use a lot of energy and oxygen when they are busy processing information. The brain appears to be compartmentalized in some way so that different areas process different types of information. So, at least in theory, if you can measure where energy is being used while a person is performing a certain task, then you can deduce what each brain area does. And for people with ASD, perhaps you could find areas that are not being used when they should be.

Click here to find out how the activity of a brain area is measured.

4. Measuring the chemical composition of a brain area
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Neurons function by communicating with other neurons. One of the ways that a neuron can "talk" to another neuron is by transferring a specific chemical, or neurotransmitter. When researchers looked at different brain areas, they found that each area had a specific set of neurotransmitters that was different from those of other brain areas. The set of neurotransmitters found in a brain area affects the types of messages it can send to the rest of the brain.

Click here to learn how to tell what type of neurotransmitter a brain area uses.

  1. Filler AG (2010) The history, development, and impact of computed imaging in neurological diagnosis and neurosurgery: CT, MRI, DTI. Internet Journal of Neurosurgery 7 (1).
  2. Filler AG, Winn HR, Howe FA, Griffiths JR, Bell BA, Deacon TW: Axonal transport of superparamagnetic metal oxide particles: Potential for magnetic resonance assessments of axoplasmic flow in clinical neurosciece. Presented at Society for Magnetic Resonance in Medicine, San Francisco, SMRM Proceedings 10:985, 1991.
  3. Roy CS, Sherrington CS (January 1890). "On the Regulation of the Blood-supply of the Brain". Journal of Physiology 11 (1–2): 85–158.17.
  4. Ogawa S, Lee TM, Nayak AS, Glynn P (1990) Oxygenation-sensitive contrast in magnetic resonance image of rodent brain at high magnetic fields. Magnetic Resonance in Medicine 14 (1): 68–78. PMID: 2161986.
  5. Niedermeyer E. and da Silva F.L. (2004). Electroencephalography: Basic Principles, Clinical Applications, and Related Fields. Lippincot Williams & Wilkins.
  6. Cohen D. "Magnetoencephalography: evidence of magnetic fields produced by alpha rhythm currents." Science 1968;161:784-6.
  7. Rosen Y, Lenkinski RE (2007). "The Recent advances in magnetic resonance neurospectroscopy". Neurotherapeutics 27 (3): 330–45.