Posts tagged electrical signals
Articles and news from the latest research reports.
After 100 Years, Understanding the Electrical Role of Dendritic Spines
It’s the least understood organ in the human body: the brain, a massive network of electrically excitable neurons, all communicating with one another via receptors on their tree-like dendrites. Somehow these cells work together to enable great feats of human learning and memory. But how?
Researchers know dendritic spines play a vital role. These tiny membranous structures protrude from dendrites’ branches; spread across the entire dendritic tree, the spines on one neuron collect signals from an average of 1,000 others. But more than a century after they were discovered, their function still remains only partially understood.
A Northwestern University researcher, working in collaboration with scientists at the Howard Hughes Medical Institute (HHMI) Janelia Farm Research Campus, has recently added an important piece of the puzzle of how neurons “talk” to one another. The researchers have demonstrated that spines serve as electrical compartments in the neuron, isolating and amplifying electrical signals received at the synapses, the sites at which neurons connect to one another.
The key to this discovery is the result of innovative experiments at the Janelia Farm Research Campus and computer simulations performed at Northwestern University that can measure electrical responses on spines throughout the dendrites.
A paper about the findings, “Synaptic Amplification by Dendritic Spines Enhances Input Cooperatively,” was published November 22 in the journal Nature.
“This research conclusively shows that dendritic spines respond to and process synaptic inputs not just chemically, but also electrically,” said William Kath, professor of engineering sciences and applied mathematics at Northwestern’s McCormick School of Engineering, professor of neurobiology at the Weinberg College of Arts and Sciences, and one of the paper’s authors.
Nerve signal discovery backs Nobel winner’s theory
Scientists have proved a 60-year-old theory about how nerve signals are sent around the body at varying speeds as electrical impulses.
Researchers tested how these signals are transmitted through nerve fibres, which enables us to move and recognise sensations such as touch and smell.
The findings from the University of Edinburgh have validated an idea first proposed by Nobel laureate Sir Andrew Huxley.
It has been known for many years that an insulating layer – known as myelin – which surrounds nerve fibres is crucial in determining how quickly these signals are sent.
This insulating myelin is interrupted at regular intervals along the nerve by gaps called nodes.
Scientists, whose work was funded by the Wellcome Trust, have now proved that the longer the distance between nodes, the quicker the nerve fibres send signals down the nerves.
The theory that the distance between these gaps might affect the speed of electrical signals was first proposed by Sir Andrew Huxley, who won the Nobel Prize in 1963 for his work on electrical signalling in the nervous system, and who died earlier this year.
The study, published in the journal Current Biology, will help provide insight into what happens in people with nerve damage. It will also shed light on how nerves develop before and after birth.
Professor Peter Brophy, Director of the University of Edinburgh’s Centre for Neuroregeneration, said: “The study gives us greater insight into how the central and peripheral nervous systems work and what happens after nerves become injured. We know that peripheral nerves have the capacity to repair, but shorter lengths of insulation around the nerve fibres after repair affect the speed with which impulses are sent around the body.”
The researchers found that when the myelin reached a certain length, the speed with which nerves impulses were conducted reached a peak.
The study, carried out in mice, also confirmed that a protein – periaxin – plays a key role in regulating the length of myelin layers around nerve fibres.
(Source: eurekalert.org)