|
Phineas Gage's miraculous survival after an explosion drove a13-pound, 3-foot-7-inch rod into his left cheek and out of the topof his head in 1848 made him the most famous case in the history ofneuroscience based on his survival of this horrific accident, whichdestroyed most of his left frontal lobe, but also because of theimpact his profound injury had on his personality and behavior. According to his friends, Gage changed from being a good-natured25-year-old to being fitful, disrespectful and profane, a personwho was "no longer Gage." Since Gage's accident, numerous scientists have studied and arguedabout the exact location and degree of damage to Gage's cerebralcortex and the subsequent effect on his personality. UCLA researchers have now, for the first time, been able to performa more comprehensive examination of Gage's brain by usingbrain-imaging data lost to science for a decade. A study in PLoS One describes the damage to the white matter "pathways" that connectvarious regions of the brain. Jack Van Horn, an UCLA assistantprofessor of neurology, and his team discovered that the rodintersected about 4% of Gage's cerebral cortex, damaging over 10%of his total white matter. The rod's passage caused widespreaddamage throughout Gage's brain, which is likely to be one of thekey reasons for Gage's changed behavior. The myelin sheath is an insulating layer made from protein andfatty substances that forms around the brain's nerves and allows aquick and efficient transmission of impulses along the nerve cells.If myelin is damaged, the impulses slow down and can lead todysfunction and disease. Given that the white matter and its myelinsheath connect billions of neurons that allow reasoning and memory,examining Gage's brain not only sheds light on the mysterysurrounding him, but also will ultimately result in a betterunderstanding of multiple brain disorders that are partially causedby similar damage to these connections. Van Horn, a member of UCLA's Laboratory of Neuro Imaging (LONI), anambitious joint effort with Massachusetts General Hospital and theNational Institutes of Health, declared: "What we found was a significant loss of white matter connectingthe left frontal regions and the rest of the brain. We suggest thatthe disruption of the brain's 'network' considerably compromisedit. This may have had an even greater impact on Mr. Gage than thedamage to the cortex alone in terms of his purported personalitychange." LONI maps trillions of microscopic links between each of thebrain's 100 billion neurons, the so-called 'connectome'. Mappingthe brain's physical wiring will ultimately provide answers interms of the causes of mental conditions that may be associatedwith the breakdown of these connections. The researchers felt thatre-investigation into the damage of Gage's brain could be abeneficial case study for LONI, in addition to being historicallyinteresting. Gage's 189-year-old skull is on display at Harvard Medical School'sWarren Anatomical Museum. However, given that the skull is nowfragile and cannot be subjected to medical imaging again, theresearchers managed to track down the last known imaging data from2001 that was lost for over a decade. They recovered the computedtomographic data files and were able to reconstruct the scans inthe highest-quality resolution possible to model Gage's skull. Theythen used advanced computer methods to model and determine therod's precise path as it shot through Gage's skull. Given the fact that the original brain tissue was obviously longgone, the researchers used modern-day brain images of matchingmales in terms of Gage's age and the fact that he was right-handed,assuming that they had a similar anatomy to Gage, beforepositioning a composite of these 110 images into Gage's virtualskull using computer software. Van Horn discovered that almost 11% of Gage's white matter and 4%of his cortex were damaged, saying: "Our work illustrates that while cortical damage wasrestricted to the left frontal lobe, the passage of the tampingiron resulted in the widespread interruption of white matterconnectivity throughout his brain, so it likely was a majorcontributor to the behavioral changes he experienced. Connectionswere lost between the left frontal, left temporal and right frontalcortices and the left limbic structures of the brain, which likelyhad considerable impact on his executive as well as his emotionalfunctions." Despite Gage's change in personality, he was eventually able totravel and find employment as a stagecoach driver for several yearsin South America before he died in San Francisco 12 years after hisaccident. Van Horn remarked that Gage's predicament has a modern parallel. He said: "The extensive loss of white matter connectivity, affectingboth hemispheres, plus the direct damage by the rod, which waslimited to the left cerebral hemisphere, is not unlike modernpatients who have suffered a traumatic brain injury . And it is analogous to certain forms of degenerative diseases,such as Alzheimer's disease or frontal temporal dementia , in which neural pathways in the frontal lobes are degraded, whichis known to result in profound behavioral changes." Van Horn stated that the quantification of the changes toGage's brain's pathways could potentially provide importantinsights in terms of modern-day brain trauma patients' clinicalassessment and outcome monitoring. Written By Petra Rattue Copyright: Medical News Today Not to be reproduced without permission of Medical News Today Additional References Citations. I am an expert from plastic-injectionmould.com, while we provides the quality product, such as Silicone Rubber Keypads Manufacturer , China Permanent Mold Casting, Silicone Rubber Keypads,and more.
Related Articles -
Silicone Rubber Keypads Manufacturer, China Permanent Mold Casting,
|
