Faulty Circuits : Biological Malfunctions Underlie Psychological Disorder
He first presented a study performed at the National Institute of Mental Health on a serotonin transporter gene of participants with and without depression. It was found that the participants with a short variation of the gene showed smaller brain tissue volume in area 25, which has a great amount of serotonin transporters. Area 25 plays an important role in fear, memory and self esteem. Thus, it is very possible that the “short gene” underlies the maldevelopment and disfunction of area 25, which then correlates with depression.
He next gave an example of OCD as evidence for his argument. Neuroimaging of the patients with OCD shows abnormal activity in an adjacent loop that includes the orbitalfrontal cortex, which is a vital place for decision making. Moreover, it was found in the OCD therapy that the patients’ symptom improvement goes along consistently with their decrease in orbitalfrontal cortical activity. It was clear that the biological disfunction underlies the psychological disorder.
He explained how PTSD is a failure of extinguishing fear. After that, he mentioned the studies by Greg Quirk on fear extinction. Greg Quirk’s studies shows that blocking the infralimbic region impaires the extinction ability. Thus, biological factors…