Until recently, neurobiologists had used computers for simulation, data collection, and data analysis, but not for interacting directly with nerve tissue in living behaving animals. Although digital computers and nerve tissue use voltage waveforms to transmit and process information, engineers and neurobiologists still have to cohesively link electronic signage of digital computers with electronic signaling of nervous tissue in freely behaving animals. Recent advances in microelectromechanical systems (MEMS), CMOS electronics and integrated computer systems will finally enable us to link computer circuits with neuronal cells in living animals and in particular with re-identifiable cells with known specific neural functions. The key components of a brain-computer system include neural probes, analog electronics, and a miniature microcomputer. Researchers developing neuronal probes such as submicron MEMS probes, microchamps, microprocessor arrays and similar structures can now penetrate and establish electrical contact with nerve cells without causing significant or long term damage to the probes or cells.
Researchers developing analog electronics, such as low-power amplifiers and analog-to-digital converters, can now integrate these devices with microcontrollers into a single, low-power CMOS chip. In addition, researchers developing integrated computer systems can now incorporate all the core circuits of a modern computer into a single silicon chip that can run on a tiny power of a small watch battery. In short, engineers have all the parts they need to build truly implantable computer systems. Until now, high signal-to-noise recording as well as digital processing of real-time neural signals have only been possible in restricted laboratory experiments. By combining MEMS probes with analog electronics and modern CMOS computing in autonomous implantable microsystems, implantable computers will free neuroscientists from the lab.
Neurons and neural networks decide, remember, modulate and control every sensation, thought, movement and act of the animal. The intimate details of this network, including the dynamic properties of individual neurons and neuronal populations, give a nervous system the power to control a wide range of behavioral functions. The goal of understanding these details motivates many workers in modern neurobiology. To make significant progress, these neurobiologists need methods to record the activity of neurons or sets of individual neurons, for long time scales, with high fidelity, in animals that can interact freely with their sensory world and express normal behavioral responses.