11 March 2009

Visualizing Intelligence & Genetics of Fear

Brain imaging is improving so quickly that soon we may be able to measure intelligence using brain scans, and simply skip the IQ tests altogether.
... lesions in the left frontal cortex were associated with lower scores on the verbal comprehension index; lesions in the left frontal and parietal cortex (located behind the frontal lobe) were associated with lower scores on the working memory index; and lesions in the right parietal cortex were associated with lower scores on the perceptual organization index.

Somewhat surprisingly, the study revealed a large amount of overlap in the brain regions responsible for verbal comprehension and working memory, which suggests that these two now-separate measures of cognitive ability may actually represent the same type of intelligence, at least as assessed using the WAIS.

The details about the structure of intelligence provided by the study could be useful in future revisions of the WAIS test so that its various subtests are grouped on the basis of neuroanatomical similarity rather than on behavior, as is the case now.

In addition, the brain maps produced by the study could be used as a diagnostic aid. Clinicians could combine the maps with their patients' Wechsler test results to help localize likely areas of brain damage. "It wouldn't be sufficient to be diagnostic, but it would provide information that clinicians could definitely use about what parts of the brain are dysfunctional," Adolphs says.

The converse--using brain-scan results to predict the IQ of patients as measured by the Weschler test--may also be possible. Although the results wouldn't be as clear-cut as they are in patients with brain lesions, Adolphs says, "you could take a large sample of healthy brains and measure the relative volumes of specific brain areas and draw some associations with these IQ factors." _Eurekalert
This study used scans of persons with brain lesions to correlate with Wechsler test scores. Future brain scans will reveal far more detail anatomically and functionally. As spatial and temporal resolution of brain imaging improves, the newer brain imaging should provide far more insight into the neural correlates of intelligence.

On another topic, research into the neuroscience of fear is revealing the importance of genetic polymorphisms in the experience and recovery from fear and anxiety in everyday life.
The results showed that while the participants with the shorter version of the serotonin transporter gene developed a very strong physiological fear response to picture A, participants with a longer version of the gene did not. In addition, a variation in the gene coding for the COMT enzyme was associated with fear extinction - volunteers with this particular variant were able to very quickly overcome their fear while volunteers with the other variant failed to do so.

The researchers note that these findings have very interesting implications for understanding gene-environment interactions and that "genes may act through the environment by making carriers of particular gene combinations more likely than other individuals to easily pick up and retain fear of stimuli associated with threat and trauma." The authors go on to suggest that these findings may indicate that individuals with specific polymorphisms may be more susceptible to anxiety disorders by being more prone to developing fear and being less likely to overcome that fear by common cognitive behavioral treatments which are based on the extinction principle. _SD
We are all unique in our responses to our different environments. While some are certainly predisposed genetically to experience more fear and anxiety in response to ordinary everyday experiences, we should all be allowed to learn how to overcome fear and anxiety responses in order to be able to pursue our life's goals. In the absence of such training to overcome innate anxiety responses, individuals can be prone to obsessing on perceived external obstacles to success. Such obsession on externals makes it almost impossible to understand the far more important internal obstacles to reaching satisfactory plateaus of achievement.

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