Neuroimaging intelligence testing

Neuroimaging intelligence testing concerns the use of neuroimaging techniques to evaluate human intelligence. Neuroimaging technology has advanced such that scientists hope to use neuroimaging increasingly for investigations of brain function related to IQ.

Traditional IQ tests observe the test-taker's performance in a standardized battery of samples of behavior. The resulting IQ standard score is the subject of much investigation as psychologists check correlations between IQ and other life outcomes. The Wechsler IQ tests for adults and for children have long been regarded as the "gold standard" in IQ testing.

The varying techniques of imaging-based testing search for different signs of intelligence. The types of intelligence analyzed in this review were fluid intelligence (Gf), general intelligence (g), and crystallized intelligence (Gc). Early studies utilized information from patients with brain damage, noticing changes in intelligence scores that correlated to certain regions of the brain. As imaging technology has improved, so has the ability for deeper neuro-analysis. MRI studies have found that the volume of gray matter correlates to intelligence, providing evidence for generalizations made regarding brain/head-size and intelligence. Additionally, PET and fMRI studies have revealed more information regarding the functionality of certain regions of the brain. By recording and interpreting the brain activity of subjects as they complete a variety of tasks, researchers are able to draw connections between the types of task (and thus, the type of intelligence) that calls on particular areas of the brain. This is interesting as knowing how parts of the brain are utilized may reveal more information about the structure and hierarchy used in neural development. It also may provide interesting information regarding the pathways of neural signals as they navigate the nervous system. Image-based testing may allow researchers to discover why certain neurons are connected, if they are indeed aligned in a purposeful manner and consequently, how to repair such pathways when they are damaged.

In general, there have been two types of intelligence studies: psychometric and biological. Biological approaches make use of neuroimaging techniques and examine brain function. Psychometrics focuses on mental abilities. Ian Deary and associates suggest that a greater overlap of these techniques will reveal new findings.

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