Orbitofrontal Cortex
Older news items (pre-2010) brought over from the old website
May 2009
Meditation may increase gray matter
Adding to the increasing evidence for the cognitive benefits of meditation, a new imaging study of 22 experienced meditators and 22 controls has revealed that meditators showed significantly larger volumes of the right hippocampus and the right orbitofrontal cortex, and to a lesser extent the right thalamus and the left inferior temporal gyrus. There were no regions where controls had significantly more gray matter than meditators. These areas of the brain are all closely linked to emotion, and may explain meditators' improved ability in regulating their emotions.
Luders, E. et al. 2009. The underlying anatomical correlates of long-term meditation: Larger hippocampal and frontal volumes of gray matter. NeuroImage, 45 (3), 672-678.
http://www.eurekalert.org/pub_releases/2009-05/uoc--htb051209.php
August 2007
Gene predicts better outcome as cortex normalizes in teens with ADHD
Recent research found that thickening of brain areas that control attention in the right cortex (right orbitofrontal/inferior prefrontal and posterior parietal cortex ) was associated with better clinical outcomes in ADHD. A new study has found that these brain areas are thinnest in those who carry a particular variant of a gene. The version of the dopamine D4 receptor gene, called the 7-repeat variant, was found in nearly a quarter of youth with ADHD and about one-sixth of the healthy controls. Although this particular gene version increased risk for ADHD, it also made it more likely that the areas would thicken during adolescence, with consequent improvement in behaviour and performance.
Shaw, P. et al. 2007. Polymorphisms of the Dopamine D4 Receptor, Clinical Outcome, and Cortical Structure in Attention-Deficit/Hyperactivity Disorder. Archives of General Psychiatry, 64, 921-931.
http://www.eurekalert.org/pub_releases/2007-08/niom-gpb080107.php
August 2003
Key brain link in associative learning directly observed
Rat studies have now shown that the amygdala supports the formation of new associations by changing nerve cell firing patterns in a different but connected part of the brain. In earlier studies, the researchers had demonstrated that nerve cells in the amygdala and the orbitofrontal cortex changed their firing patterns to reflect new associations between cues and outcomes. In this later study, they examined how changes in neural activity in amygdala might be supporting changes in the orbitofrontal cortex. Rats were first deprived of water, then repeatedly given either desirable drinking water, laced with sugar, or undesirable drinking water, laced with quinine. The associations then learned would show up in the orbitofrontal cortex when the rats smelled the odor cue. The same activation patterns did not however, show up in those rats who had their amygdala chemically lesioned (although these rats still learned to avoid the undesirable drinking water). Specifically, although lesioned rats had neurons in the orbitofrontal cortex that were responsive to the odor cues, they did not have neurons that were responsive in anticipation of the predicted outcome. The responsive neurons were also less associative, more responsive to the identity of the cue rather than the association betwen odor and consequence.
Schoenbaum, G., Setlow, B., Saddoris, M.P. & Gallagher, M. 2003. Encoding Predicted Outcome and Acquired Value in Orbitofrontal Cortex during Cue Sampling Depends upon Input from Basolateral Amygdala. Neuron, 39, 855-867.
http://www.eurekalert.org/pub_releases/2003-08/jhu-kbl082803.php