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December 04, 2008

Scientists Explore the Neuroanatomy of Depression

In an article in the November issue of the Journal of Neuroscience researchers Michael Koenigs, Edward D. Huey, Matthew Calamia, Vanessa Raymont, Daniel Tranel, and Jordan Grafman submitted an article entitled “Distinct Regions of Prefrontal Cortex Mediate Resistance and Vulnerability to Depression”. The study looked at the anatomy of the prefrontal cortex and discovered the different influences certain sub regions have on depression.

The study started from analysis of brain images of a “depressed brain”, that is a brain of a person with some kind of depression disorder. This analysis led researchers to the conclusion that there are abnormal patterns of activity in the prefrontal cortex of the depressed brain. It has long been known that the prefrontal cortex is associated with personality and mood and therefore mood disorders, but study of specific sub nuclei has been limited.

In this particular paper Koenigs et al. looked at patients with brain lesions (damage to specific parts of the brain). They focused on subjects with lesions in the ventromedial prefrontal cortex (vmPFC) and the dorsolateral prefrontal cortex (dlPFC), two sections that showed particularly abnormal behavior on the brain scan. The images below show the location of the vmPFC and the dlPFC in the human brain. The first image shows the vmPFC highlighted in pink and the second image shows the dlPFC in green.

source: Wikipedia.com

source: Google Images

The subjects with damage to the vmPFC were significantly less likely to have depression. This shows that vmPFC likely plays a strong role in the susceptibility of one becoming depressed, on the other hand a damaged dlPFC increased the likelihood of having depression in turn showing that the dlPFC could be involved in resistance to depression.

While these findings may seem minor at first look in reality they are hugely beneficial to the understanding and future research on depression. There are many factors involved in depression, so much so that the research can be overwhelming. However, by specifying two sub regions that play dramatic roles in the disorder researchers can focus their study and attempt to develop more complex studies to understand what goes wrong in these regions causing depression. Future studies will focus on these regions and what can be done to change the abnormalities in order to treat and possibly prevent depression.

Posted by horr at 03:06 AM

December 02, 2008


This blog will focus on a slightly different subject than my past entries but will still focus on the most recent developments in Neuroscience research. Schizophrenia, which literally means “split mind”, is a brain disorder characterized by disorganized thoughts and in many cases hallucinations and delusions. One of the horrifying parts of schizophrenia is the late and sudden onset of the disease. The neurological factors of Schizophrenia are largely unknown to scientists and early detection for the disorder is difficult. Schizophrenia onset is usually in the early twenties and can occur in a variety of fashions. Some forms of Schizophrenia can be successfully treated allowing a person to live a normal life, however, there are forms that even with treatment leave the patient debilitated and ostracized from the public.

Recently a study was published successfully locating a brain malfunction that causes Schizophrenia. The article is called “NIH Scientists Identify Link Between Brain Systems Implicated in Schizophrenia” and was conducted by Andres Buonanno, Ph.D. and colleagues at the Eunice Kennedy Shriver National Institute of Child Health and Human Development, a NIH lab. Three distinct brain areas are believed to be a part in Schizophrenia, this study looked at the relationships between the three areas and how a breakdown in the communication between brain areas could be to blame for Schizophrenia. More specifically, researchers believe that a malfunction in the intermediary circuit linking between the three brain circuits could be the culprit.

One of the three systems is the glutamatergic system. This system is involved in long-term memory. The researchers discovered that a molecule called Neuregulin-1 controls the release of Dopamine, Dopamine in turn controls brain electrical activity levels in the glutametergic system. Dopmine can have a myriad of effects in the body and based on what receptor in binds to can have profoundly different effects on memory. It is now believed that an imbalance of Dopamine binding and the effects that has on the glutametergic system could be one cause of Schizophrenia.

source: Google images
The above depicts a Dopamine molecule binding to a receptor. Depending on what type of receptor Dopamine can have dramatically different effects including storing long term memories and even erasing existing memories. The binding of Dopamine to receptors is an important part of the glutamatergic system, on of the three systems now believed to be linked in the cause of Schizophrenia.

This research is a huge break in the understanding of Schizophrenia and is based on the research of many parties. The hope is that with this new information regarding the origins of the disorder newer and more efficient treatments can be developed. Current Schizophrenia treatments focus on blocking Dopamine receptors; however, newer treatments could focus on the Neuregulin-1 molecule or the glutamatergic system. These treatments would be more effective and potentially have fewer side effects then current treatments.

Posted by horr at 07:28 PM