How to Prevent Neurons from Dying after Brain Injury

Electrical stimulation of the brain by applying current to the eye may help retinal nerve cells to survive injury. While these neurons may not be restored to full function, they are prevented from dying. But to achieve survival, their interconnections, the dendritic tree, needs to disconnect rapidly for the protective action to unfold. In a study published in Scientific Reports, researchers from Magdeburg University (Germany) and The Chinese University of Hong Kong report that for rats and mice, repetitive transorbital alternating current stimulation (rtACS) may help preserve visual neurons from cell death after injury.

Because the tissue at the back of the eye, the retina, is part of the brain, researchers can directly observe how brain cells react in the living animal. The researchers repeatedly monitored neurons in both rat and mouse retinas after an optic nerve injury and measured neuronal death after this lesion. Surprisingly, a neuroprotective treatment with electrical alternating current stimulation increased cellular survival in the eye´s retina, but it also induced a fast and complete stripping-off of the neuron’s dendritic tree. The dendrites are like a tree receiving many thousands of signals from other neurons. This enables them to process visual information and then transmit the signals along the optic nerve towards the brain. By retracting its dendrites, the cell withdraws itself from this intercellular communication network and becomes silent — which helps its survival.

The test animals were divided into groups and subjected to both real and sham treatments. For the rats, optic nerve crush (ONC) was used to induce an injury in some of the animals to mimic glaucoma. Some animals and not others (sham) were treated with rtACS, resulting in three test groups: ONC/rtACS, ONC/Sham, and Sham/Sham. Using in vivo confocal neuroimaging (ICON) and measurements of Visual Evoked Potentials (VEP), the researchers could determine whether a neuron had survived and whether it was still functioning. The ONC and the first rtACS stimulation were done on day zero. ICON was performed on day 4, followed by rtACS or sham stimulation. On day 7 post ONC another ICON was performed.

For the mice, a confocal laser ophthalmoscope was used to image the dendritic structures of the retina for three groups of subjects, ONC/rtACS, ONC/Sham and Sham/rtACS. The mice received rtACS on days 0, 3, 6, 9 and 12 after ONC and images were taken on days 3, 7 and 14.

According to lead author Petra Henrich-Noack, PhD, Institute of Medical Psychology, Otto-von-Guericke University, Magdeburg, Germany, “With our experiments, we have detected so far unknown ‘silent survivor cells’ in the brain and it will be exciting to find out whether they later die or can be reactivated.” Surprisingly, neurons in the retina of animals that survived better when treated with rtACS lost their dendritic tree completely within the first 3 days after the lesion. The authors suggest that this early structural isolation might protect the neurons from the “toxic” excitation that is known to appear soon after brain damage.

 

 

Story Source:

Materials provided by Institute for Medical Psychology, Otto-v.-Guericke University Magdeburg. Note: Content may be edited for style and length.

Journal Reference:

Petra Henrich-Noack, Elena G. Sergeeva, Torben Eber, Qing You, Nadine Voigt, Jürgen Köhler, Sebastian Wagner, Stefanie Lazik, Christian Mawrin, Guihua Xu, Sayantan Biswas, Bernhard A. Sabel, Christopher Kai-Shun Leung. Electrical brain stimulation induces dendritic stripping but improves survival of silent neurons after optic nerve damage. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-00487-z


 

 

New Test to Quickly Identify Mild Traumatic Brain Injury

A new test using peripheral vision reaction time could lead to earlier diagnosis and more effective treatment of mild traumatic brain injury, often referred to as a concussion. Identify Brain Injury

A new test using peripheral vision reaction time could lead to earlier diagnosis and more effective treatment of mild traumatic brain injury, often referred to as a concussion, according to Peter J. Bergold, PhD, professor of physiology and pharmacology at SUNY Downstate Medical Center and corresponding author of a study newly published online by the Journal of Neurotrauma.

While most patients with mild traumatic brain injury or concussion fully recover, a significant number do not, and earlier diagnosis could lead to better management of patients at risk for developing persistent symptoms, according to Dr. Bergold and his co-authors.

Lingering symptoms may include loss of concentration and/or memory, confusion, anxiety, headaches, irritability, noise and light sensitivity, dizziness, and fatigue.

“Mild traumatic brain injury is currently diagnosed with subjective clinical assessments,” says Dr. Bergold. “The potential utility of the peripheral vision reaction test is clear because it is an objective, inexpensive, and rapid test that identifies mild traumatic brain injury patients who have a more severe underlying injury.”

Dr. Bergold’s co-authors include colleagues from the University of Texas Southwestern Medical Center; The University of Texas at Dallas; Washington University; the National Institute of Neurological Disorders and Stroke; the Uniformed Services University of the Health Sciences; and SUNY Downstate.

The article published by the Journal of Neurotrauma is titled “Measurement of Peripheral Vision Reaction Time Identifies White Matter Disruption in Patients with Mild Traumatic Brain Injury.”

[embedyt] http://www.youtube.com/watch?v=aKZnMC5vzhU[/embedyt]

Story Source:

Materials provided by SUNY Downstate Medical Center. Note: Content may be edited for style and length.


Journal Reference:

  1. Kyle B. Womack, Christopher Paliotta, Jeremy F. Strain, Johnson S. Ho, Yosef Skolnick, William W. Lytton, L. Christine Turtzo, Roderick McColl, Ramon Diaz-Arrastia, Peter J. Bergold. Measurement of Peripheral Vision Reaction Time Identifies White Matter Disruption in Patients with Mild Traumatic Brain Injury. Journal of Neurotrauma, 2017; DOI:10.1089/neu.2016.4670

SUNY Downstate Medical Center. “New test may quickly identify mild traumatic brain injury with underlying brain damage.” ScienceDaily. ScienceDaily, 16 February 2017. <www.sciencedaily.com/releases/2017/02/170216120538.htm>.

 

What is a Diffuse Axonal Injury? (DAI)

As tissue slides over tissue, a shearing injury occurs. This causes the lesions that are responsible for unconsciousness, as well as the vegetative state that occurs after a severe head injury. A diffuse axonal injury also causes brain cells to die, which cause swelling in the brain.”
DAI is characterized by axonal separation, in which the axon is torn at the site of stretch and the part distal to the tear degrades. While it was once thought that the main cause of axonal separation was tearing due to mechanical forces during the trauma, it is now understood that axons are not typically torn upon impact; rather, secondary biochemical cascades, which occur in response to the primary injury (which occurs as the result of mechanical forces at the moment of trauma) and take place hours to days after the initial injury, are largely responsible for the damage to axons.
Though the processes involved in secondary brain injury are still poorly understood, it is now accepted that stretching of axons during injury causes physical disruption to and proteolytic degradation of the cytoskeleton.[1] It also opens sodium channels in the axolemma, which causes voltage-gated calcium channels to open and Ca2+ to flow into the cell. The intracellular presence of Ca2+ unleashes several different pathways, including activating phospholipases and proteolytic enzymes, damaging mitochondria and the cytoskeleton, and activating secondary messengers, which can lead to separation of the axon and death of the cell.

Different Contacts for Help Pertaining TBI

Audio:

Brain Injury Association of America
www.biausa.org
800-444-6443

Centers for Disease Control and Prevention
www.cdc.gov
800-311-3435

Defense and Veterans Brain Injury Center
www.dvbic.org
800-870-9244

Health Resources and Services Administration
www.hrsa.gov
301-443-3376

National Association of State Head Injury Administrators
www.nashia.org
301-656-3500

National Brain Injury Research Treatment and Training Foundation
www.nbirtt.org
434-220-4824

National Center for Medical Rehabilitation Research, NICHD, NIH
www.nichd.nih.gov/about/ncmrr
800-370-2943

National Institute on Disability and Rehabilitation Research
www.ed.gov/about/offices/list/osers/nidrr
202-245-7640

National Institute of Neurological Disorders and Stroke, NIH
www.ninds.nih.gov
800-352-9424

North American Brain Injury Society
www.nabis.org
703-960-6500

Social Security Administration
www.ssa.gov
800-772-1213