The project VSAMUEL aims to develop easy-to-use instrumentation for multi-channel recordings from functioning and living nervous tissue spanning a broad range of neurobiological questions. It integrates advanced micro structuring techniques to batch fabricate multi-site microelectrode probes with novel PC based real-time data acquisition and signal processing. The development will ascend gradually from 32 to 64 to 128 recording sites, to reach a channel density suitable to answer unprecedented research questions. The overall shape of the silicon-based probes resembles tiny forks but the test target area determines the locations and arrangement of the incorporated recording sites. The superiority of our equipment over recordings from hand built single channel electrodes will be shown by testing them at target areas, which span the central and peripheral nervous systems.
The current understanding of how the nervous system functions is based on numerous observations of the behaviour of single units or a small ensemble of units correlated to some external stimulation or behavioural event. However, the processing power of the nervous system lies in its network and interconnections. Thus the key to understanding the nervous system is to make simultaneous observations of the activity of numerous cells. VSAMUEL's objective is to develop such a system and then to make available to the neuroscience research community. It will be based on silicon microelectrode arrays for acquiring signals from nervous tissue in vivo. The project will utilise advanced micro-structuring to design and fabricate probes with an increasing number of recording sites: 32, 64 or 128 sites placed on tiny fork shaped probes. This will not only include development of easy-to-use connectors and suitable multi-channel signal amplifiers, but also a novel high-quality, high-throughput data acquisition system. We will prove the superiority of our new equipment with key studies of multi-unit recordings in animal experiments in relevant and growing new fields in neuroscience.
Work scheduled for achieving the objective of a versatile and advanced multi-site recording system, will fall into several work packages. Although they are split into groups involved in building and those involved in testing, development will take place with close and constant interaction between testers and builders. We will start with development, design and fabrication of the probes and support instrumentation for 32 site recordings. The number of sites will eventually increase to 128 recording sites using a double-sided lithography process to place sites on both sides of the probe's shafts. The needs of the experimental groups will determine the location and arrangement of the microelectrodes. Anatomical and mechanical requirements will influence the shape of the probe's shafts. In parallel to the silicon work, we will develop and fabricate both a macroscopic, easy-to-handle connectors and a miniaturised signal amplifier system. Modular design will ensure easy scale up as the number of sites on a probe increases. Data acquisition will be performed on an inexpensive computer platform by adapting off-the-shelf signal processor cards. This will enable to tackle complex software tasks involving spike analysis and sorting, or data compression. Moreover, the software will facilitate the set-up of a "virtual lab" interface to allow remote access and control of real experiments. Pointing to the future, VSAMUEL will work towards achieving a biocompatible probe suitable for human implants and develop ways to fabricate probes on-demand to allow rapid turnover on customised designs. Close communication between end-user and instrument designer will ensure the best possible end product, especially since each new technological development will be immediately evaluated in practical experiments. One participant will record extra-cellular field responses during acute experiments performed on the isolated guinea pig brain in vitro. Another plans to record activity
Milestones will consist of the successful implementation of silicon probes on operational recording instruments to be used in real experiments with up to 128 recording sites (month [M]12: 32; M18: 64; M36: 128). Instruments will be used in neurobiological experiments and will provide exciting results with insertions and recordings from targeted regions of the nervous system. The increase in recording sites with a single insertion, simple to use connectors, amplifiers and user driven design may ultimately lead to a quantum leap in the understanding of the nervous system.
-Rack mounted miniaturized preamp/amp for modulo 64 channels
-Custom designed 32 and 64 microelectrodes Si- probes with 8 differing designs each set
-Flexible connectors for probes with 32 and 64 channels
-Prototype of DSP based data acquisition system for modulo 32 channels with online spike detection, clustering and classification @ 50kSamples/sec rate
-Field potential recordings from in vitro experiments with whole brain preparations for epilepsy research
-Worlds first in vivo acute recordings from cerebellum with Si probes
-Preliminary results from acute intrafascicular adaptation and recordings
-Patent on generalization of probe production for on-demand designs
-Remote Internet-based use of recording system by Virtual Network Computing
-Study on potential new materials for probes
-Preliminary investigation on chronic implantation results
Funding SchemeCSC - Cost-sharing contracts
164 40 Stockholm-kista