-Caveat Lector-
Research reveals anatomy of suppressed memories: study 7/12/07 US researchers have identified the parts of the brain that are involved with suppressing unpleasant memories, a finding that could have implications for treating depression or post traumatic stress disorder, according to a study released Thursday....The concept of memory suppression has been a controversial one among psychologists for a century, but in this study neuroscientists used brain scans to show that volunteers who have been asked to banish disturbing memories show very specific patterns of brain activity. The scans showed that two specific regions of the prefrontal cortex -- what neuroscientists call the seat of cognitive control -- appear to work in tandem to modulate posterior brain regions like the visual cortex, the hippocampus and amygdala. These areas are involved in tasks such as visual recall, memory encoding and retrieval and emotional expression. "These results indicate memory suppression does occur, and, at least in nonpsychiatric populations, is under the control of the prefrontal cortex," the investigators reported in the journal Science. For the purpose of the experiment, the 16 volunteers were given 40 pairs of photographs to study. In each case, an image of a neutral human face was paired with an emotionally disturbing image such as a car crash, a wounded soldier, an electric chair or a violent crime scene. After memorizing each pair, the volunteers were placed in an MRI (magnetic resonance imaging) scanner. Once inside the machine, they were shown only the neutral face images and instructed to either actively recall the associated image or to actively suppress it. The results of the scans or fMRIs (functional magnetic resonance imaging) indicated that the volunteers were able to "exert some control over their emotional memories," said Brendan Depue, a doctoral student in neuroscience at the University of Colorado at Boulder, and lead author of the study. "By essentially shutting down specific portions of the brain, they were able to stop the retrieval process of particular memories," Depue said. _http://www.physorg.com/news103471796.html_ (http://www.physorg.com/news103471796.html) Traumatic Stress Induces Brain Change in Children 3/5/07 Michael Smith Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco Stanford, Calif., March 5 -- Children with post-traumatic stress disorder, similar to adults, show physical changes in the brain, according to researchers here. In a pilot study of 15 children, higher PTSD scores and higher cortisol levels were significantly (P<0.05) correlated with relative decreases over time in the volume of the right hippocampus, reported Victor Carrion, M.D., of Stanford, and colleagues, reported in the March issue of Pediatrics. On the other hand, there was no correlation with changes in the left hippocampal volume, Dr. Carrion and colleagues found. In adults, PTSD is associated with lower hippocampal volumes compared with adults who do not have stress disorder, Dr. Carrion and colleagues noted, but such a relation hasn't been shown in children. _http://psychiatrictimes.com/psychiatryNews/showArticle.jhtml?articleID=197800148&cid=PT-news-toc-071207_ (http://psychiatrictimes.com/psychiatryNews/showArticle.jhtml?articleID=197800148&cid= PT-news-toc-071207) Science 13 July 2007: Vol. 317. no. 5835, pp. 215 - 219 DOI: 10.1126/science.1139560 Research Articles - Prefrontal Regions Orchestrate Suppression of Emotional Memories via a Two-Phase Process Brendan E. Depue,1,2* Tim Curran,1,2,3 Marie T. Banich1,2,3,4 Whether memories can be suppressed has been a controversial issue in psychology and cognitive neuroscience for decades. We found evidence that emotional memories are suppressed via two time-differentiated neural mechanisms: (i) an initial suppression by the right inferior frontal gyrus over regions supporting sensory components of the memory representation (visual cortex, thalamus), followed by (ii) right medial frontal gyrus control over regions supporting multimodal and emotional components of the memory representation (hippocampus, amygdala), both of which are influenced by fronto-polar regions. These results indicate that memory suppression does occur and, at least in nonpsychiatric populations, is under the control of prefrontal regions. _http://www.sciencemag.org/cgi/content/short/317/5835/215_ (http://www.sciencemag.org/cgi/content/short/317/5835/215) ************************************** Get a sneak peak of the all-new AOL at http://discover.aol.com/memed/aolcom30tour www.ctrl.org DECLARATION & DISCLAIMER ========== CTRL is a discussion & informational exchange list. 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