Cognitive Substraction: Why Brain Imaging Techniques aren’t always accurate

In imaging, there are certain methodologies, like the cognitive subtraction methodology. In this method, activity in a control task in subtracted from activity in an experimental task. So for example, take a word task. A simple model of written word recognition is used. In a famous experiment, the Peterson et al. (1988) experiment, they wanted … Continue reading Cognitive Substraction: Why Brain Imaging Techniques aren’t always accurate

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PET scans versus fMRI

We have discussed PET scans and fMRI. Now the question is, which one of the two is better? Over the last decade or so, fMRI has been more widely used than PET scans. This is because fMRI has better temporal and spatial resolution compared to PET scans. Also, fMRI does not use radioactivity, while PET scans do. … Continue reading PET scans versus fMRI

Brain Imaging Alphabetical Soup: Making Sense of CAT, PET, MRI, fMRI, SPECT: fMRI

This article will focus on fMRI imaging.fMRI, or functional magnetic resonance imaging, uses MRI equipment. fMRI is sensitive to the amount of deoxyhemoglobin in the blood. We know that when neurons consume oxygen, the neurons convert oxyhemoglobin to deoxyhemoglobin. Now, deoxyhemoglobin has magnetic properties, and these magnetic properties therefore introduce distortions in the local magnetic … Continue reading Brain Imaging Alphabetical Soup: Making Sense of CAT, PET, MRI, fMRI, SPECT: fMRI

Brain Imaging Alphabetical Soup: Making Sense of CAT, PET, MRI, fMRI, SPECT: PET scans

Structural imaging measures permanency. In other words, it measures the permanent, structural characteristics of the brain. Functional imaging measures more of the variability, the moment-to-moment changes of the brain that are associated with various cognitive processes, such as attention. We know the brain consumes about 20% of the body’s total energy. A lot of this … Continue reading Brain Imaging Alphabetical Soup: Making Sense of CAT, PET, MRI, fMRI, SPECT: PET scans

Brain Imaging Alphabetical Soup: Making Sense of CAT, PET, MRI, fMRI, SPECT: MRI

I started this mini-series with the articles on how imaging got started, and on CT scans. Now we'll move on to MRI scans.MRI, or magnetic resonance imaging, is used to create images of the body's tissues, specifically of the soft tissues, like organs. X-rays pass through soft tissues undistorted and relatively easily. Now, most human … Continue reading Brain Imaging Alphabetical Soup: Making Sense of CAT, PET, MRI, fMRI, SPECT: MRI

Brain Imaging Alphabetical Soup: Making Sense of CAT, PET, MRI, fMRI, SPECT: CAT Scans

We've all heard the abbreviations: CAT, PET, MRI, fMRI, SPECT.Now what the heck do they all mean? Brain imaging has an interesting start. But generally, brain imaging techniques fall into two broad categories: Structural imaging, and Functional imaging. Structural imaging does just what its name implies: it provides images of the structure of the brain. … Continue reading Brain Imaging Alphabetical Soup: Making Sense of CAT, PET, MRI, fMRI, SPECT: CAT Scans