The body of knowledge about the human brain is growing exponentially, but questions big and small remain unanswered. Researchers have been using electrode arrays to map electrical activity in different brain regions to understand brain function. Until now, however, these arrays have only been able to detect activity over a certain frequency threshold. A new technology developed in Barcelona overcomes this technical limitation, unlocking the wealth of information found below 0.1 Hz and paving the way for future brain-computer interfaces.
Developed at the Barcelona Microelectronics Institute (IMB-CNM, CSIC), the Catalan Institute of Nanoscience and Nanotechnology and the CIBER in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), and adapted for brain recordings in collaboration with the August Pi i Sunyer Biomedical Research Institute (IDIBAPS), the technology moves away from electrodes and uses an innovative transistor-based architecture that amplifies the brain’s signals in situ before transmitting them to a receiver. Furthermore, the use of graphene to build this new architecture means the resulting implant can support many more recording sites than a standard electrode array; it is also slim and flexible enough to be used over large areas of the cortex without being rejected or interfering with normal brain function. The result is an unprecedented mapping of the kind of low-frequency brain activity known to carry crucial information about events in the brain such as the onset and progression of epileptic
Beyond epilepsy, though, this precise mapping and interaction with the brain has other exciting applications. Taking advantage of the capability of the transistor configuration to create arrays with a very large number of recording sites via a so-called multiplexing strategy, the technology is also being adapted by the researchers to restore speech and communication as part of the European project BrainCom. Led by the ICN2, this project will deliver a new generation of brain-computer interfaces able to explore and repair high-level cognitive functions with a particular focus on the kind of speech impairment caused by brain or spinal cord injuries (aphasia).
Details of the underlying technological advances can be found in Nature Materials.
The graphene microtransistors were adapted for brain recordings and tested in vivo at IDIBAPS, led by ICREA Prof. Mavi Sánchez-Vives. An imaging technique was developed in collaboration with ICFO, led by ICREA Prof. Turgut Durduran (ICFO is a center of BIST).
Source: Catalan Institute of Nanoscience and Nanotechnology Photo Credits: ICN2
Tool could open up the brain to precision DNA-editing techniques which allow cellular functions to be turned on or changed at will
Researchers have shown it’s possible to temporarily block the brain from forming new memories using a combination of sound waves, viruses and drugs.
Using ultrasound blasts California Institute of Technology (Caltech) researchers have been able to temporarily open the brain’s protective barrier to treatments, where usually surgery would be required.
In this way they hope it could one day be possible to non-invasively manage epilepsy, Parkinson’s disease and other neurological conditions that currently rely on going under the knife.
However in the shorter term it is more likely the advance, dubbed “acoustically targeted chemogenetics” in the journal Nature Biomedical Engineering on Monday, will enhance scientists ability to understand these conditions in animal trials.
“By using sound waves and known genetic techniques, we can, for the first time, non-invasively control specific brain regions and cell types as well as the timing of when neurons are switched on or off,” said assistant professor of chemical engineering Mikhail Shapiro.
It is possible to use a virus to implant a desired genetic change in the DNA of cells and this allows certain functions of the cell to be switched on or off in response to an instruction from a tailor-made drug.
However getting these instructions across the blood-brain barrier, which keeps out all but the smallest molecules and evolved to protect the sensitive organ from poisons and invaders like viruses, remains a problem.
Dr Shapiro and his team showed that they could overcome this with ultrasound blasts and microscopic bubbles injected into the blood stream.
When the sound waves hit the blood borne bubbles it forces them to vibrate and the jostling opens the barrier for a short time.
To demonstrate the effect of this precision tool the Caltech team targeted memory formation in mice.
They used a virus to write the instructions into neurons in a part of the brain known as the hippocampus, which is also important in Alzheimer’s disease.
Then several weeks later mice received either the drug to switch off these neurons or an injection of saline, and were subjected to electric shocks in a new room of their enclosure, and then put in the same room again the next day.
Mice which had not had their memories blanked out by the drug were twice as likely to freeze in fear when they were placed back in the room where they had been electrocuted, but other behavioural tests were unaffected.
“This method is reversible,” says Jerzy Szablowski, the lead researcher of the study. “You can administer a drug to turn off neural cells of interest, but, with time, those cells will turn back on.”
Being able to precisely target regions of the brain in this manner could equally be used in the treatment of epilepsy where sever forms require neurosurgery to remove parts of the brain responsible for lethal seizures.
“This is an impressive, innovative approach that will be useful for many neuroscientists,” says pharmacology professor Bryan Roth of the University of North Carolina, who was not involved in this study.
Epileptic seizures strike with little warning and nearly one third of people living with epilepsy are resistant to treatment that controls these attacks. More than 65 million people worldwide are living with epilepsy.
The US Food and Drug Administration (FDA) granted premarket approval for Medtronic’s Deep Brain Stimulation DBS) therapy as adjunctive treatment for reducing the frequency of partial-onset seizures in individuals 18 years of age or older who are refractory to 3 or more antiepileptic medications.
The therapy delivers controls electrical pulses to the anterior nucleus of the thalamus, a target in the brain that is part of a network involved in seizures. (more…)
NEW TECHNOLOGY BREAKTHROUGH
Klas Tybrandt, principal investigator at the Laboratory of Organic Electronics at Linköping University, has developed new technology for long-term stable neural recording. It is based on a novel elastic material composite, which is biocompatible and retains high electrical conductivity even when stretched to double its original length.
The result has been achieved in collaboration with colleagues in Zürich and New York. The breakthrough, which is crucial for many applications in biomedical engineering, is described in an article published in the prestigious scientific journal Advanced Materials.
The coupling between electronic components and nerve cells is crucial not only to collect information about cell signalling, but also to diagnose and treat neurological disorders and diseases, such as epilepsy.