Neuropixels probes could revolutionise neuroscience
A game-changing device for the neuroscience field was today described in Nature. The Neuropixels probes will allow scientists to simultaneously record from more individual neurons than ever before.
Troy Margrie, Professor of Systems Neuroscience at UCL and head of the Margrie Lab at Sainsbury Wellcome Centre commented “This is arguably the most significant technical advance in the field of extracellular electrical recording in a generation.”
The ability of animals to perceive and make their behavioural choices depends on the concerted activity of many neurons distributed throughout the brain. Understanding this coordinated signalling has been challenging because it was not possible to measure concurrently the activity of many neurons across different brain regions on time scales relevant for behaviour.
Traditional technologies have provided data from very small areas of the brain due to limitations on the number of wire electrodes that can be placed in the brain simultaneously. The Neuropixels probes, made from silicon thinner than a human hair and containing 960 recording sites, will enable scientists to simultaneously record across multiple different brain regions.
“This state-of-the-art technology permits sampling from an unprecedented number of individual neurons simultaneously recorded in multiple brain regions. This probe is particularly well suited to mammalian brains and deep structures where optical approaches remain challenging. It increases data throughput, reduces animal numbers and, importantly, permits the interrogation of individual cell activity within and across distributed networks while the animal is engaging in the same behavioural task. This capability places us in a strong position to better study and understand the pathways and mechanisms of sensory, motor and cognitive processes that are believed to be widely distributed throughout our brain,” said Margrie.
The probes were developed through a collaboration between scientists at HHMI Janelia Research Campus, the Allen Institute for Brain Science and UCL together with engineers at the nanotechnology company imec and the project was funded by Howard Hughes Medical Institute, Gatsby Charitable Foundation, Allen Institute for Brain Science and Wellcome.
John O’Keefe of the Sainsbury Wellcome Centre at UCL and lead PI on the Wellcome and Gatsby Charitable Foundation grants said he was eager for British involvement in the project right from the beginning. “It was clear to me that if these probes worked they would take our ability to relate single cell activity and behaviour to a new level. And they would be particularly useful in cortical areas related to spatial memory such as the hippocampus and entorhinal cortex. In the past we have had to put several implants with multiple tetrodes into these brain regions to collect enough data to do network analysis, to see how the cells interacted to form spatial representations, or to do decoding analysis where we try to figure out the animal’s position from the cell activity. Now we can place one Neuropixels probe along the length of the entorhinal cortex and record from twice as many grid cells as we could before, or record simultaneously from place cells in the CA1 and CA3 regions of the hippocampus, opening up a whole new level of analysis.”
At 10 mm long and 70x20 µm wide, the Neuropixels probes are roughly the same length as a mouse or rat brain. Rodent brains are used by neuroscientists as models for the human brain as they share a lot of structure and connectivity. The new approach will help researchers elucidate the brain circuits that underpin the ability to process information and make decisions and hopefully one day will help us to understand diseases such as depression and Alzheimer’s.
The Neuropixels probes should also help to reduce laboratory animal numbers. The probes have been tested in long-duration experiments of up to 150 days in freely moving animals. This will allow researchers to study how learning and experience changes the brain and also the effects of neurodegenerative processes in disease.
Tiago Branco, Senior Research Fellow at Sainsbury Wellcome Centre, said “This new probe technology opens the possibility of recording activity from hundreds of individual neurons in multiple brain regions at the same time, with exceptional resolution. It’s extremely exciting, as it will give us for the first time a window into how computations are distributed and organised in the brain. The next big challenge will be to develop methods for analysing and making sense of all of the data.”
Yoh Isogai, Senior Research Fellow at Sainsbury Wellcome Centre, remarked "There is no shortage of new and exciting questions we can tackle using neuropixels probes. For example, we can now record the activities of a large number of genetically identified neurons in multiple brain areas. We are thrilled to apply this cutting edge method to our studies of social behaviors."
The Nature paper describes the development of Neuropixels probes and the seven design goals. Scientists from the consortium will present data collected using prototype Neuropixels probes at the Annual Meeting of the Society for Neuroscience in Washington, DC, November 11-15, 2017.
Read the full paper in Nature: Fully integrated silicon probes for high-density recording of neural activity
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