What is fMRI?

fMRI stands for functional Magnetic Resonance Imaging. It’s a large machine that scans the brain by creating a magnetic force that allows researchers to track blood flow to the different areas. Since active neurons require more blood, this lets researchers know which areas of the brain are active as the patient thinks about or experiences something. (Swaminathan, 2008) Blood flow is slower than neural-activity, whereas neurons fire within milliseconds, the corresponding increase in blood flow peaks 3 to 5 seconds later. (Hillman, 2014) The thing that separates this from normal MRI is the “functional” part, which allows one to monitor the brain as it is engaging in thought, or functioning.

What you should know about fMRI

1. The machine requires a person to remain still. They are strapped into a gurney and rolled into the machine, where they might view images or video depicted on a screen while doctors monitor brain activity. The apparatus may be scary for some young children, and since it requires them to remain still, may be uncomfortable.

2. fMRI has been a valuable tool that allows researchers to peer into the mind, but its practical results are often oversold. It’s as much art as science. All regions of the brain are constantly active at all times, so what doctors must do is try to decipher “spikes” in certain brain regions that rise above the background noise that is already there. Moreover, the smallest unit of measurement under fMRI is a voxel, which accounts for an area a few millimeters on each side. This may seem like a precise measurement, but that small area contains around 5.5 million neurons. Moreover, some neurons fire up to stop other neurons from firing, so dampening signals might actually be misread as activity for something else. Finally, the data sets produced by the machine are so large that they must be run through a mathematical filter; which is what ultimately produces those bright images that show the brain “lighting up.” Random fluctuations in brain activity may also skew results. (Sanders, 2009; Logothetis, 2008) The bottom line? It’s a great tool for research, but is far more a blunt hammer than a precise tool for measurement.

3. fMRI is sometimes used to check a person against “normal” brain activity or to gauge responses to particular stimuli. But beware of people who try to claim that it can read a person’s thoughts or provide any sort of definitive conclusions. It merely shows which regions of the brain are more active at a particular time than others, and even this can be problematic. Of particular concern to us, some professionals may try to use fMRI scans as a diagnostic tool for conditions such as ADHD or other behavioral issues. Other companies are trying to develop it into a lie detection tool, which is a blatant misuse and abuse of its capabilities. (A fortune teller might provide you with a more accurate lie detection service.) So beware of people who overstate the technology’s use.

4. There is extra reason for concern when it comes to the use of this technology with children. As biomedical professor Elizabeth Hillman states, “for almost as long as the imaging technology has been around, scans of the brains of infants and young children have looked very different from those of adults. In adults, an uptick in nueronal activity usually means and increase in the fMRI signal. In infants, many researchers saw a decrease in the signal.” This is because fMRI doesn’t actually measure nureonal activity, it measures blood flow, and the nuerovascular system in a young brain is not yet “synched up” creating differences in what the scan shows. Thus “fMRI might be blind during the early stages of brain development.” (Hillman, 2014, p. 62-63)