This article summarizes some interesting publications that came out in August. As usual, there were many interesting developments, both in fundamental neuroscience and neurology, and in practical aspects of dealing with and treating brain-related diseases and disorders.
On August 20, the scientific community marked the birthday of Roger Sperry. Prof. Sperry received the 1981 Nobel Prize for Medicine and Physiology for his works on “split-brain” patients. In these patients, the corpus callosum connecting two brain hemispheres is severed. The works of Roger Sperry helped to establish that our two brain hemispheres do have different functions and often work independently.
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Brain maintains representation of amputated hand decades later
It was traditionally assumed that after amputation of a hand or a finger the part of the brain representing it becomes “overwritten” due to the absence of input signals. New data demonstrate that this view is not correct and brain retains the picture of missing limb even several decade later. The findings might prove useful in creating neuroprosthetics – artificial limbs controlled directly by brain signals.
New blood test predicts the likelihood of developing Alzheimer’s disease in the future
Although early Alzheimer’s disease often manifests itself as a mild memory impairment, only some of patients with memory impairment will eventually develop this condition. New blood test developed by British scientists allows to predict the likelihood of developing the Alzheimer’s in the next few years in patients with mild memory problems. The test would help to identify vulnerable patients and advise them early on the course of action to prevent or delay the disease progression.
Parkinson’s disease spreads via intercellular nanotubes
Like most other neurodegenerative diseases, Parkinson’s disease is linked to formation and spread of protein aggregates, alpha-synuclein in the case of this condition. However, not much is known about the mechanisms responsible for the transfer of protein aggregates between the neural cells in brain. This month, researchers reported that alpha-synuclein aggregates can migrate from one cell to another along tunnelling nanotubes. The findings represent a serious breakthrough in understanding Parkinson’s disease and point to some new potentially useful therapeutic targets.
Lead causes oxidative stress in neural stem cells
Environmental exposure to lead is known to cause neurodevelopmental problems, particularly at early stages of life. The molecular mechanisms behind this effect remained unclear, however. Now scientists have found that lead induces oxidative stress in neural stem cells. Specifically, proteins SPP1 and NRF2 were found to be involved in this process. Both proteins are involved in cognitive development.
Genetic reprogramming can convert connective tissue cells into neurons
Genetic reprogramming of mature cells to create pluripotent stem cells was discovered 10 years ago. A number of improved technics for cellular reprogramming was invented since then. A novel revolutionary technique called CRISPR was recently used to convert the cells of connective tissue into neurons. The discovery may pave the way to model neurological disorders and develop cell therapy.
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Stopping exercise at older age leads to decreased cerebral blood flow
The fact that fitness level drops quite quickly after stopping exercise is well known, but the changes in brain caused by termination of the regular exercise routine are not well studied. In a new research, scientists asked well trained senior athletes aged 50-80 years to stop exercising for 10 days, and then studied their cerebral blood flow. It turned out that all athletes experienced significantly decreased level of resting blood flow in a number of key areas of brain. Importantly, the blood flow was decreased in hippocampus, a part of brain crucial for learning and memory. Researchers believe that stopping exercise at older age may trigger the processes connected to the development of dementia and other neurodegenerative conditions.
Larger brain, not different brain structure, differentiates us from primates
For a long time, scientists believed that our remarkable cognitive abilities are linked to the enlarged prefrontal cortex region of the brain. As the new article published this month shows, this idea was wrong. In both humans and non-human primates, the prefrontal cortex occupies 8% of the brain. Human brain, however, is much bigger and contains 16 billion cortical neurons, while other higher primates have only 6-9 billion of these cells. Apparently, this increased number of neurons, rather than larger prefrontal cortex, is behind our enhanced cognitive abilities.
Calcium supplements increase risk of dementia in women with history of stroke
Osteoporosis is a common problem in elderly women, and calcium supplementation is usually recommended to manage this condition. It turned out, however, that taking calcium supplements is not as safe as it was believed. Women with cerebrovascular diseases such as stroke and white matter lesions are at much higher risk of developing dementia when they regularly take calcium supplements. The risk is 7 times higher among women with a history of stroke who take supplements compared to women with a history of stroke who don’t supplement their diet with calcium. The molecular mechanism behind this phenomenon remains unclear.
Drugs for epilepsy may cause psychotic disorders
People with epilepsy are known to be prone to psychiatric disorders, but it appears that the part of problem is the very drug used to control epileptic seizures. New study revealed that in one out of seven epilepsy patients, the psychiatric disorders can be attributed to the use of this drugs. Women and people with temporal lobe epilepsy are particularly vulnerable to this side effect.
Better education of clinicians needed to avoid misdiagnosis of multiple sclerosis
Due to its rather unspecific manifestations and the lack of reliable biomarkers, multiple sclerosis (MS) can be a challenging condition to diagnose correctly. New study suggests that numerous patients misdiagnosed with other conditions received potentially harmful treatment for a disease they didn’t have. Moreover, the study also shows that in most cases the misdiagnoses were linked to not following the existing diagnostic guidelines and criteria correctly. Better education of clinicians is required to avoid misdiagnosis of MS and recognising patients who were diagnosed incorrectly.
References:
Sanne Kikkert, James Kolasinski, Saad Jbabdi, Irene Tracey, Christian F Beckmann, Heidi Johansen-Berg, Tamar R Makin. Revealing the neural fingerprints of a missing hand. eLife, 2016; 5 DOI: 10.7554/eLife.15292
Svetlana Hakobyan, Katharine Harding, Mohammed Aiyaz, Abdul Hye, Richard Dobson, Alison Baird, Benjamine Liu, Claire Louise Harris, Simon Lovestone, Bryan Paul Morgan. Complement Biomarkers as Predictors of Disease Progression in Alzheimer’s Disease. Journal of Alzheimer’s Disease, 2016; 1 DOI: 10.3233/JAD-160420
Saïda Abounit et al. Tunneling nanotubes spread fibrillar ?-synuclein by intercellular trafficking of lysosomes. The EMBO Journal, 2016 DOI: 10.15252/embj.201593411
Quan Lu, David C. Christiani, Robert O. Wright, Tomas R. Guilarte, Kirstie Stanfield, Li Su, Yongyue Wei, Rory Kirchner, Zhaoxi Wang, Hae-Ryung Park, Peter J. Wagner. In Vitro Effects of Lead on Gene Expression in Neural Stem Cells and Associations between Upregulated Genes and Cognitive Scores in Children. Environmental Health Perspectives, 2016; DOI: 10.1289/EHP265
Joshua B. Black, Andrew F. Adler, Hong-Gang Wang, Anthony M. D’Ippolito, Hunter A. Hutchinson, Timothy E. Reddy, Geoffrey S. Pitt, Kam W. Leong, Charles A. Gersbach. Targeted Epigenetic Remodeling of Endogenous Loci by CRISPR/Cas9-Based Transcriptional Activators Directly Converts Fibroblasts to Neuronal Cells. Cell Stem Cell, 2016; DOI: 10.1016/j.stem.2016.07.001
Alfonso J. Alfini, Lauren R. Weiss, Brooks P. Leitner, Theresa J. Smith, James M. Hagberg, J. Carson Smith. Hippocampal and Cerebral Blood Flow after Exercise Cessation in Master Athletes. Frontiers in Aging Neuroscience, 2016; 8 DOI: 10.3389/fnagi.2016.00184
Mariana Gabi, Kleber Neves, Carolinne Masseron, Pedro F. M. Ribeiro, Lissa Ventura-Antunes, Laila Torres, Bruno Mota, Jon H. Kaas, Suzana Herculano-Houzel. No relative expansion of the number of prefrontal neurons in primate and human evolution. Proceedings of the National Academy of Sciences, 2016; 201610178 DOI: 10.1073/pnas.1610178113
Jürgen Kern, MD, PhD et al. Calcium supplementation and risk of dementia in women with cerebrovascular disease. Neurology, August 2016 DOI: 10.1212/WNL.0000000000003111
Ziyi Chen, Ana Lusicic, Terence J. O’Brien, Dennis Velakoulis, Sophia J. Adams, Patrick Kwan. Psychotic disorders induced by antiepileptic drugs in people with epilepsy. Brain, 2016; aww196 DOI: 10.1093/brain/aww196
Andrew J. Solomon, Dennis N. Bourdette, Anne H. Cross, Angela Applebee, Philip M. Skidd, Diantha B. Howard, Rebecca I. Spain, Michelle H. Cameron, Edward Kim, Michele K. Mass, Vijayshree Yadav, Ruth H. Whitham, Erin E. Longbrake, Robert T. Naismith, Gregory F. Wu, Becky J. Parks, Dean M. Wingerchuk, Brian L. Rabin, Michel Toledano, W. Oliver Tobin, Orhun H. Kantarci, Jonathan L. Carter, B. Mark Keegan, Brian G. Weinshenker. The contemporary spectrum of multiple sclerosis misdiagnosis. Neurology, 2016; 10.1212/WNL.0000000000003152 DOI: 10.1212/WNL.0000000000003152
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