tag:blogger.com,1999:blog-3904639295706642486.post4194552838710760426..comments2023-10-21T08:48:37.363-07:00Comments on Zone-Reflex: Neural communication outside synapses I. The mystery and magic of glia.Unknownnoreply@blogger.comBlogger2125tag:blogger.com,1999:blog-3904639295706642486.post-76391439052353859892011-03-07T22:27:56.575-08:002011-03-07T22:27:56.575-08:00http://www.dana.org/news/features/detail.aspx?id=3...http://www.dana.org/news/features/detail.aspx?id=30798<br />Brain's Use of 'Alternative Energy' May Be Related to Alzheimer's<br /><br />Energy-deficit?<br /><br />the regions where A-beta deposits are seen in the brains of people with Alzheimer’s closely match the regions that normally rely heavily on less-efficient but faster processes of energy production in cells. The studies’ authors propose that A-beta in its disease-driving forms might impair these processes, and thus might principally harm the brain regions that most depend on them.<br /><br />Adult cells usually make ATP in a multi-step process that includes the simple sugar glucose and oxygen and leaves water and carbon dioxide as byproducts. But there are faster, less-efficient ways of turning glucose into ATP, and some cellular processes in the brain depend on them. These faster processes, which don’t require oxygen, account for only 10–15 percent the adult brain’s use of glucose and are used more extensively by fetal cells and cancer cells, and by muscle cells during intense exercise.<br /><br />These non-oxygen-consuming uses of glucose in the brain increase temporarily when brain activity increases. these alternative uses of glucose seemed to vary considerably from region to region in ordinary brains. Also piquing his interest was the observation that the regions that relied the most on these alternate energy processes appeared to be the ones that make up the “default mode network,” a set of brain regions that are relatively active when a person is not engaged in any specific task. the regions that make up the network are also the ones that gather the most A-beta deposits.<br /><br />More reduction? Bigger systems? More coherence?<br /><br />One possible explanation for the finding is that these alternate glucose uses are especially vulnerable to disruption by A-beta.<br /><br />Raichle points out that glucose-fuelled processes are used by helper cells known as astrocytes to keep concentrations of the neurotransmitter glutamate below toxic levels in the synapses of cortical neurons. In principle, disruption of these processes by A-beta could lead to the deaths of the neurons. A-beta in its disease-causing forms does alter the metabolism of astrocytes, apparently putting them under stress and ultimately weakening the neurons they are meant to protect. “One of the things that astrocytes do is to remove A-beta from the extracellular space, <br /><br />evidence of a similar abnormality in glycolysis in Huntington’s disease, suggests testing to see whether glucose use affects A-beta deposition rather than vice-versa.Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.comtag:blogger.com,1999:blog-3904639295706642486.post-69667438410755056082011-03-06T12:27:17.826-08:002011-03-06T12:27:17.826-08:00http://brainblogger.com/2010/07/12/mind-your-immun...http://brainblogger.com/2010/07/12/mind-your-immune-system/<br />Mind your Immune System<br />a “hair pulling” disorder, very similar to its human counterpart trichotillomania.<br />the basis of this psychological aberration was a reduced population of microglia, which are the immune system cells in the brain. The genetic mutation responsible was pinpointed to the Hox8 gene, which belongs to a family of genes that determine body plan and architecture in all vertebrates, apart from regulating development and growth of organs. The brain microglia cells are thought to originate from the bone marrow, and are the only brain cells that express this gene — thus they are thought to play a key role in the brain’s development. <br />if bone marrow containing Hox8 expressed stem cells (early forms which give rise to microglia) were transplanted to affected mice, their hair pulling disorder was cured within four months. By contrast when bone marrow from affected mice was transplanted into normal ones, the disorder appeared in normal ones.<br /><br />Apart from the fact that this is the world’s first reported behavior transplant, this finding is an important landmark in our understanding of the genetic basis of behavior. To what extent are our behaviors pre-determined by our immune system and our mind interconnected? To what extent does a malfunction of one lead to problems with the other?<br /><br />Chen SK, Tvrdik P, Peden E, Cho S, Wu S, Spangrude G, & Capecchi MR (2010). Hematopoietic origin of pathological grooming in Hoxb8 mutant mice. Cell, 141 (5), 775-85 PMID: 20510925Ullahttps://www.blogger.com/profile/16634036177244152897noreply@blogger.com