Tag Archives: science
Researchers from The Ohio State University have announced they have discovered how blows to the head cause numerous small swellings along the length of neuronal axons. The study, “Polarity of varicosity initiation in central neuron mechanosensation,” which will be published June 12 in The Journal of Cell Biology, observes the swelling process in live cultured neurons and could lead to new ways of limiting the symptoms associated with concussive brain injuries.
Mild traumatic brain injuries, or concussions, cause a variety of temporary symptoms, including headache, nausea, and memory loss. But the effects of concussive impacts on neurons in the brain are poorly understood. One such effect is the development of “axonal varicosities,” small, bead-like swellings that appear along the length of neuronal axons, which are the parts of neurons that transmit electrical and chemical signals to neighboring nerve cells. Similar swellings are seen in the degenerating axons of Alzheimer’s and Parkinson’s patients.
Chen Gu and colleagues at The Ohio State University discovered that they could induce the formation of axonal varicosities in hippocampal neurons grown in the lab by “puffing” them with bursts of liquid from a small pipette. The pressure exerted by these puffs was similar to the forces neurons might experience after a blow to the head.
The axonal varicosities formed rapidly, particularly in younger neurons where they swelled up within 5 seconds of being puffed. A surprise to the researchers was that the varicosities disappeared several minutes after puffing, indicating that they are not a sign of irreversible axon degeneration.
Gu and colleagues could also induce axonal varicosities by repeatedly puffing cultured neurons with shorter bursts of liquid, mimicking the effects of repetitive, subconcussive impacts. Accordingly, the team also saw axonal varicosities in the brains of mice subjected to repeated light blows to the head.
The researchers found that puffing activated a mechanosensitive channel protein called TRPV4, which is enriched in the membrane of neuronal axons and allows calcium ions to enter the cell. Inhibiting this channel blocked the formation of axonal varicosities.
After entering axons through activated TRPV4 channels, calcium ions appear to disrupt the microtubule cytoskeleton by inhibiting a microtubule-stabilizing protein called STOP. This interrupts the transport of cellular materials along axonal microtubules, causing these materials to accumulate at several points along the axon where they may give rise to varicosities.
Older neurons, which are more resistant to the effects of puffing, express lower levels of TRPV4 and higher levels of STOP. “It will be interesting to determine whether these factors make a mature brain more resistant to mild traumatic brain injury than a young brain,” says Gu.
Puffing didn’t induce varicosities along the lengths of dendrites, the parts of neurons that receive chemical signals from neighboring nerve cells. Instead, the researchers found that dendritic, but not axonal, varicosities could be induced by prolonged treatment with glutamate, an excitatory neurotransmitter that is released from damaged axons.
“Taken together, our findings provide novel mechanistic insights into the initial stage of a new type of neuronal plasticity in health and disease,” says Gu, who points out that axonal varicosities have also been observed in healthy brains where neurons may respond to mechanical signals from their environment. “This process may therefore play a key role in neural development and central nervous system function in adults, as well as in chronic brain disorders and various acute brain injuries.”
“The science could determine that all that matters for CTE is the concussive hits you took before your 18th birthday,” lawyer Paul Clement, a former U.S. solicitor general, argued Thursday for the NFL.
That passage from an Associated Press story yesterday could send shock waves through the sports world and reinforce what concussion experts have said all along — kid shouldn’t play tackle football until high school.
For more on this developing story, visit www.nflconcussionlitigation.com
With a theme of “Grey Matters: Discerning the Impacts of Head Injury,” the Krost Symposium 2015 will be held October 7-8 in Houston. Dr. Robert Cantu and Chris Nowinski will give the keynote address for the conference, which will be held at Texas Lutheran University on October 8 at 8:30 a.m. in the Jackson Auditorium.
The event, which is free and open to the public, focuses on raising awareness and understanding of brain injury as guest speakers discuss prevention and education regarding sports-related head trauma, cognitive rehabilitation, and the effects of post-traumatic stress disorder. In addition to awareness, the symposium will review strategies in preventing, treating, and rehabilitating brain injury, and critically examine the effects that brain injury and these interventions have specifically in the athletics and armed forces communities both now and as society moves into the future.
The schedule of events follows:
Tuesday, October 6, 8:00 – 9:30 p.m. (pre-event) on the Library Lawn
Pre-event Film Screening
Head Games: The Global Concussion Crisis directed by Steve James
Head Games: The Global Concussion Crisis will act as a primer and kick off to this year’s Krost Symposium. This film is inspired by the book of the same title written by Krost 2015 speaker Christopher Nowinski.
Wednesday, October 7, 7:30 – 9:00 p.m. in Jackson Auditorium
Giesber Keynote Address
Robert Cantu, M.D. and Chris Nowinski – Co-Founders of the Concussion Legacy Foundation
Thursday, October 8, 8:30 – 9:30 a.m. in Jackson Auditiorium
“Brain, Mind, and Soul: Reintegrating after Military Deployment”
Drew Helmer, M.D. – Director of the War Related Illness and Injury Study Center, U.S. Department of Veteran Affairs
Thursday, October 8, 9:30 – 10:30 a.m. in Jackson Auditorium
“Short and Long term management of TBI-related Symptoms”
Kim Gorgens, Ph.D. – Director of Continuing Education and Professional Development, University of Denver Graduate School of Professional Psychology
Thursday, October 8, 10:30 – 11:30 a.m. in Jackson Auditorium
Panel session discussing personal and clinical experience with head injury from the military, athletics and neurological perspectives
Robert Cantu, M.D.
Co-founder of the Concussion Legacy Foundation
Dr. Robert Cantu serves as chief of neurosurgery service, department of surgery chairman, and director of sports medicine at Emerson Hospital in Concord, Mass. He has authored more than 350 scientific publications, including 22 books on neurosurgery and sports medicine, and has served as associate editor and on the editorial boards of multiple sports medicine publications. Dr. Cantu published the first ever return-to-play guidelines for sports concussions in 1986 and devised the first grading system for concussions, providing medical professionals with concussion management guidelines where none existed before. As medical director of the National Center for Catastrophic Sports Injury Research, Dr. Cantu collected data that has resulted in sports safety improvements; most notably football rule changes concerning tackling and blocking, the establishment of football helmet standards, improved on-the-field medical care, and coaching techniques. He also serves as a clinical professor of neurosurgery at Boston University School of Medicine, adjunct professor of exercise and sport science at the University of North Carolina Chapel Hill, co-director of the Neurological Sports Injury Center at Brigham and Women’s Hospital in Boston, and neurosurgical consultant to the Boston College Eagles football team and Boston Cannons professional lacrosse team. He has appeared on 60 Minutes, NFL Today, ABC World News Tonight, ESPN’s Outside the Lines, and HBO’s Real Sports.
Co-founder of the Concussion Legacy Foundation
Chris Nowinski is co-founder and executive director of the Concussion Legacy Foundation (formerly Sports Legacy Institute), a nonprofit organization dedicated to solving the sports concussion crisis. He also serves as a co-director of the Center for the Study of Traumatic Encephalopathy (CSTE) at Boston University School of Medicine. A former Harvard football player and WWE professional wrestler, Nowinski was forced to retire after he suffered a series of concussions in 2003. Diagnosed with post-concussion syndrome, he began a quest to better understand this condition. It wasn’t until he visited renowned neurosurgeon Robert Cantu that he was first exposed to medical research that revealed how concussions and brain trauma were misunderstood in the sports world. Realizing the lack of awareness among athletes, coaches, and even medical professionals—that ultimately only cost him his career and threatened the health and well being of athletes of all ages—led him to write the critically acclaimed book, Head Games: Football’s Concussion Crisis. Through his continued advocacy and investigative work, he has raised this issue into the national spotlight. To continue this groundbreaking research, he co-founded the Sports Legacy Institute with Dr. Cantu in 2008. As of 2012, the CSTE has studied the brains of over 140 athletes postmortem and has redefined our understanding of chronic traumatic encephalopathy, proving the disease extends into college and youth football, hockey, and other sports. His team’s research has been featured in almost every major newspaper and television network. His May 2007 profile on HBO’s Real Sports with Bryant Gumbel won the Emmy for Sports Journalism. A second HBO Real Sports episode aired in January 2010, a third in August 2010 and a fourth in November 2012. In 2012, Nowinski received the United States Sports Academy Distinguished Service Award. Nowinski also serves on the Ivy League Multi-Sports Concussion Committee, the National Football League Players Association Mackey/White TBI Research Committee, and on the board of directors for the Brain Injury Association of America.
For more information, visit http://www.tlu.edu/events/krost-symposium-2015/