Functional MRI: A Radiological Window into the Mind – Part 1




Neuroscience_Neurology.jpgFunctional MRI (fMRI) is one of the most widely used experimental tools in neuroscience today, which allows us to study blood flow patterns to different parts of the brain during a given task. For example during solving mathematical problems, a typical fMRI pattern is seen. Recently however, psychological theories are being tested, and a broader picture of how the mind works is emerging.

One of the criticisms traditionally faced by psychology as a scientific discipline is the lack of objective data, to back up theories of the mind. For instance, proving the “existence” of the subconscious mind is difficult, although intuitively, the model is widely accepted.

A recent study (1) published on the subject of how knowledge is organized in our mind shows how powerful functional MRI scanning can be, as a tool to prove or disprove psychological theories. It has long been debated whether the human brain perceives living beings as a separate category than the non-living objects (concept domain), or whether, after taking into account the various features like shape, movement, and color (feature domain), it then decides whether it is living or not amongst other attributes. As several objects were presented to a group of 21 participants, detailed fMRI studies were performed of the degree of activation of different parts of the brain, while a yes/no questionnaire designed to test their understanding of concepts versus features was simultaneously analyzed. The results showed with a high degree of statistical significance that human brains organize concepts according to descriptive linguistic features, with the majority using the dominant left half of the brain, and not according to pre-existing conceptual domains of broad categories.

The issue of whether a picture of a “standard” brain from brain scan data can lead us to a “Theory of the Mind” was discussed by Harvard neuroscientist Rebecca Saxe in her paper Why and how to study Theory of Mind with fMRI. (2) Central to our radiological window in to the human mind is the concept of “Regions of Interest” or ROI, which does not presuppose that distinct areas of the human brain have specific “thinking” roles. Rather, a distinct mental activity sets off a pattern of brain activity that involve many areas on the cortex that are close by, or separated widely. In Saxe’s own research she found that while experimental subjects were reading different kinds of stories — appearance, bodily sensations, or thoughts — blood flow patterns on fMRI were distinctly different for the genre of the story, but this difference in patterns were consistent across all the subjects. What fMRI has therefore provided for us is the insight that the number of patterns of activation for different tasks is limitless, but broad patterns do exist. The bigger picture will only emerge after a lot of studies comparing sets of ROI from different experiments are pooled together, providing a clearer picture of how the mind functions through a dynamic, constantly changing network of regions across the brain.

References

1. MARQUES, J., CANESSA, N., SIRI, S., CATRICALA, E., CAPPA, S. (2008). Conceptual knowledge in the brain: fMRI evidence for a featural organization. Brain Research, 1194, 90-99. DOI: 10.1016/j.brainres.2007.11.070

2. SAXE, R. (2006). Why and how to study Theory of Mind with fMRI. Brain Research, 1079(1), 57-65. DOI: 10.1016/j.brainres.2006.01.001

Sudip Ghosh, MD

Sudip Ghosh, MD, is a surgeon at the University of Manchester, UK and a medical writer.
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