The only way to see a microorganism is with powerful equipment, and teams of neurobiologists, psychiatrists, and advanced imaging specialists from Switzerlandâ€™s EPLF and CHUV, have done just that to observe the neuronal activity in the brain. As reported in The Journal of Neuroscience, the scientists used Digital Holographic Microscopy (DHM) to observe neuronal activity at up to 150 times greater resolution, and in 3-D! This incredible employment of advanced technology has incredible potential for the research and testing of new drugs to fight neurological diseases, such as Alzheimer’s and Parkinson’s.
To observe neurons in a Petri dish, scientists have had to use florescent dyes because the neurons are transparent and come in various shapes and sizes. The lights change the chemical properties of the neurons and can cause the results to be compromised. This is also time consuming, could cause damage to the cells, and can only allow the researcher to examine a few neurons at a time. DHM allows real time observation and does not alter the neurons, or the results, in any way.
“DHM is a fundamentally novel application for studying neurons with a slew of advantages over traditional microscopes,” explains Pierre Magistretti of EPFL’s Brain Mind Institute and a lead author of the paper. “It is non-invasive, allowing for extended observation of neural processes without the need for electrodes or dyes that damage cells.”
Pierre Marquet, Senior team member added, “DHM gives precious information not only about the shape of neurons, but also about their dynamics and activity, and the technique creates 3D navigable images and increases the precision from 500 nanometers in traditional microscopes to a scale of 10 nanometers.”
Imagine a large rock on the ocean floor. As waves form around the rock they send out information about the rockâ€™s shape. You can get this information by comparing to waves that did not have to smash up against the rock, and receive a visual image of the rock shape. By pointing a single wavelength at an object, DHM can do this with a laser beam and collect the distorted image on the other side, comparing it to a reference beam. The laser beam travels through the transparent cells and relays important information about their internal structures. A computer will then numerically reconstruct a 3D image of the object – in this case neurons – using an algorithm d the authors have developed.
Along with DHM pioneer and EPFL professor in the Advanced Photonics Laboratory, Christian Depeursinge, Magistretti decided to use DHM for neurobiological applications. The process is normally applied to find defects in minute materials. Their group induced an electric charge into a culture of neurons using the main neurotransmitter in the brain, glutamate. This charge transfer carries water inside the neurons and changes their optical properties in a way that can be detected only by DHM. In this way the technique accurately visualizes the electrical activities of hundreds of neurons simultaneously, in real-time, without damaging them with electrodes. There is also no need to inject dyes or electrodes, so DHM can be applied to the screening of thousands of new pharmacological molecules.
There are important ramifications that can be developed through the use of DHM in the discovery of new drugs to combat or prevent neuro-degenerative diseases such as Parkinson’s and Alzheimer’s. With this method new molecules will be able to be tested in larger quantities, and faster than they could before.
“Due to the technique’s precision, speed, and lack of invasiveness, it is possible to track minute changes in neuron properties in relation to an applied test drug and allow for a better understanding of what is happening, especially in predicting neuronal death,” Magistretti says. “What normally would take 12 hours in the lab can now be done in 15 to 30 minutes, greatly decreasing the time it takes for researchers to know if a drug is effective or not.”
Science Daily: Holograms Reveal Brain’s Inner Workings: Microscopy Technique Used to Observe Activity of Neurons Like Never Before: Â http://www.sciencedaily.com/releases/2011/08/110816171734.htm