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Saturday, September 12, 2015

How MAGNETS "RESET" DEPRESSED BRAINS: Connectivity


The Right Anterior Insula and the Right Prefrontal Cortex
This was the first time an MRI was used to guide the TMS impulses and, at the same, time measure subtle changes in brain circuit activity.
Magnetic pulses from a device applied to the head appear to "reset" the brains of depressed patients, according to a new study from the United Kingdom.
"We found that one session of TMS modifies the connectivity of large-scale brain networks, particularly the right anterior insula, which is a key area in depression,"
The circuitry in a part of the right prefrontal cortex is known to be too active in depressed patients, causing excessive rumination and self absorption and impaired attention.
The circuitry in a part of the right prefrontal cortex is known to be too active in depressed patients, causing excessive rumination and self absorption and impaired attention. When the TMS was applied to healthy subjects in this study, the activity in that region slowed.
Recent work has identified disruption of several brain networks involving limbic and cortical regions that contribute to the generation of diverse symptoms of major depressive disorder (MDD).
Results showed a failure of reciprocal influence between insula and higher frontal regions (dorsomedial prefrontal cortex) in addition to a weakening of influences from sensory regions (pulvinar and visual cortex) to the insula.
"Alterations in Effective Connectivity aAnchored on the Insula in Major Depressive Disorder"
http://www.europeanneuropsychopharmacology.com/…/S…/abstract
Of particular interest are the networks anchored on the right anterior insula, which binds the cortical and limbic regions to enable key functions that integrate bottom-up and top-down information in emotional and cognitive processing.
Emotional appraisal has been linked to a presumed hierarchy of processing, from sensory percepts to affective states.
For the first time, we demonstrate a network-level processing defect extending from sensory to frontal regions through insula in depression.
In 16 patients with current MDD, and 16 healthy controls, we investigated differences in directional influences between anterior insula and the rest of the brain using resting-state functional magnetic resonance imaging (fMRI) and Granger-causal analysis (GCA), using anterior insula as a seed region
When the TMS was applied to healthy subjects in this study, the activity in that region slowed.
http://www.washingtonpost.com/…/magnets-change-brain-activ…/
Transcranial Magnetic Stimulation is the use of an electromagnetic coil to deliver small, powerful bursts of energy to targeted areas known to be involved in mood regulation. It is a painless, non-invasive treatment than involves no drugs, no IVs, or any other kind of sedation, and whose chief possible side effect is a headache