June 26, 2012
A new video article in JoVE, the Journal of Visualized Experiments, describes a novel procedure to monitor brain function and aid in functional mapping of patients with diseases such as epilepsy. This procedure illustrates the use of pre-placed electrodes for cortical mapping in the brains of patients who are undergoing surgery to minimize the frequency of seizures. This technique, while invasive, provides real-time analysis of brain function at a much higher resolution than current technologies.
This image shows the implanted electrodes as they are mapped on the brain. Credit: Journal of Visualized Experiments
Typically, functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) are used in neuroimaging studies but these techniques suffer from low temporal and spatial resolution. By using electrodes implanted in the brain of an epileptic patient already undergoing treatment, scientists can now image the brain with a much higher spatial resolution, lower signal interference, and a higher temporal resolution than fMRI or EEG.
The leading author of the study, Dr. Gerwin Schalk, from the New York State Department of Health and Albany Medical College, states, “Essentially, we have created a new imaging technique. Our procedure is innovative because it is prospective, meaning, it can image brain function as it occurs. Further, it does not require an expert to derive meaningful information concerning brain function.” He also notes that it was crucial for this procedure to be demonstrated in a video format. “The procedure is a very visual process. The ancillary information such as the spatial relationships of different components, the set-up of the hospital room, and the set-up of the equipment itself cannot be represented in a typical print article. The video capacities of JoVE were an excellent vehicle to demonstrate both the general set-up and the specific implementation of the mapping system.”
By relying on an epileptic patient’s neural implants, scientists gain an unprecedented insight into the brain’s function. Dr. Schalk’s procedure provides a technological advancement that can be applied in many ways, including stroke patient monitoring and rehabilitation, signal mapping and transduction for movement of prosthetic limbs, and enhancement of communication in individuals with paralysis of the vocal musculature. TheJoVE video article provides a comprehensive demonstration of the new technique, from mapping the electrical implants to interpreting the tests in real time. JoVE editor Dr. Claire Standen emphasizes, “The new imaging technique demonstrated in this article is very important. There is a definite need for better, more accurate, imaging to monitor brain function. This technique can be applied to a wide range of clinical areas within the Neuroscience field.” The article can be found here: Recording Human Electrocorticographic (ECoG) Signals for Neuroscientific Research and Real-time Functional Cortical Mapping
Provided by The Journal of Visualized Experiments
Source: medicalxpress.com
Cosmetic chemical hinders brain development in tadpoles
Image: Even small concentrations — 1.5 parts per million — of a biocide used in cosmetics interrupted neurological development in tadpole brains. There is no evidence those concentrations are harmful to humans. Credit: Aizenman lab/Brown UniversityScientists, health officials, and manufacturers already know that a chemical preservative found in some products, including cosmetics, is harmful to people and animals in high concentrations, but a new Brown University study in tadpoles reports that it can also interrupt neurological development even in very low concentrations.
In the cosmetics industry, the biocide methylisothiazolinone or MIT, is considered safe at concentrations of less than 100 parts per million. Lab studies, however, have found that lower concentrations affected the growth of animal neurons. Picking up from there, the Brown researchers performed a series of experiments to investigate how 10 days of exposure at concentrations as low as 1.5 ppm would affect whole, living tadpoles as they develop. Their results appear in advance online in the journal Neuroscience.
“The lower concentrations we studied didn’t kill the animals or cause any big deformities or affect the behavior you’d see just by looking at them,” said Carlos Aizenman, associate professor of neuroscience and the study’s senior author. “But then we decided to do a series of functional tests and we found that exposure to this compound during a period of development that’s critical for the fine wiring of the nervous system disrupted this period of fine tuning.”
Aizenman emphasized that there is no evidence in the study that any products with MIT, such as shampoos or cosmetics, are harmful to consumers.
Neurotoxic effects
When Aizenman and lead author Ariana Spawn explored the consequences of exposing tadpoles to two nonlethal concentrations, 1.5 ppm and 7.6 ppm, they found some deficits both in behavior and in basic brain development.
In one experiment they shined moving patterns of light into one side of the tadpole tanks from below. As they expected, the unexposed tadpoles avoided the light patterns, swimming to the other side. Tadpoles that had been exposed to either concentration of MIT, however, were significantly less likely to avoid the signals.
In another experiment, Aizenman and Spawn, who was an undergraduate at the time and has since graduated, exposed the tadpoles to another chemical known to induce seizures. The tadpoles who were not exposed to MIT and those exposed to the lower concentration each had the same ability to hold off seizures, but the ones who had been exposed to the 7.6 ppm concentration succumbed to the seizures significantly more readily.
