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Nanomembrane Probe Provides a New Window into the Brain
Recording signals from the brain has just become a whole lot easier. And a lot more flexible.
A new, ultra-thin device capable of recording brain activity without having to use penetrating electrodes could potentially allow researchers to learn information about the brain’s electrical activity without the invasive implantation of electrodes.
The device, is comprised of 720 silicon nanomembrane transistors in an array consisting of 360 different channels. The silicon enables it to be more flexible and foldable than a conventional rigid electrode array. This means it can be placed not only on the brain surface, but inside the grooves or sulci and the deeper fissures as well as between the brain's hemispheres.
The 360 different sensors of the new device are multiplexed in an array, which eliminates the requirement for each sensor to have its own separate wire. This arrangement allows the device to cover a much larger brain area with higher resolution than standard electrode arrays currently used by neuroscience laboratories around the world.
The team demonstrated the feasibility of the flexible electrode array by performing in vivo recordings on 10 cats using the new device. The investigators used the flexible array to observe responses to visual stimuli, electrical signals during sleep, and brain activity during induced epileptic seizures. In all three experiments, the researchers recorded types of signals that had previously only been recorded from brain slice preparations of brain, never from intact brain.
The signals observed during the seizures gave the researchers new insight into the pattern of activity that exists during epilepsy. The array recorded abnormal spiral waveforms that were very similar to the electrical signals produced by the heart during cardiac arrhythmias. The investigators, from the University of Pennsylvania School of Medicine and Bioengineering, believe that by preventing these abnormal spiral waves by breaking some of the neural connections that cause them, doctors could possibly cure epilepsy in humans.
Brain activity was also measured as the anesthetized cats observed several random sequences of visual stimuli. The flexible electrode array confirmed that different areas of the cortex responded to different types of visual stimuli, at a resolution never documented before using the standard electrode arrays.
“The new technology we have created can conform to the brain’s unique geometry, and records and maps activity at resolutions that have not been possible before,” said researcher Brian Litt in a press release. The researchers hope that the flexible electrode array can be used to better understand the brain activity patterns in other neurological disorders, such as chronic pain, depression and sleep disorders.
The investigators also believe that the flexible array could one day be implanted in the brains of humans to serve as a neuromotor prosthetic. Several standard electrode arrays are currently used in the brains of humans to help stimulate neuromuscular connections and coordinate muscle movement. However, the standard arrays are so bulky that they often cause inflammation and sometimes lead to dangerous hemorrhages.
This article was published online on Nov. 13, 2011 in the journal Nature Neuroscience.
November 27, 2011