Surface plasmon resonance imaging of neural network activity

The brain is the most sophisticated computational system known and understanding it presents one of the most challenging and rewarding problems humans have ever sought to solve. While much progress has been made in brain research, it is still unclear how the signalling between neurons results in the encoding and processing of information. A lack of tools with which to monitor this neural signalling presents a major barrier to solving this fundamental problem.All rapid information processing within the brain is mediated by action potentials, which are tiny electrical signals that propagate rapidly from neuron to neuron. The sensory information an organism receives, its thought processes, its movements and its behaviours are a direct consequence of these action potentials. It is therefore essential to be able to monitor action potentials from every neuron in a network for an extended period of time to understand how information is encoded, processed, stored and recalled by networks of neurons.During an action potential, the wall of the neuron undergoes a slight change in thickness. Because this affects the way the neuron interacts with light, it provides an opportunity to detect action potentials without the limitations of existing methods. Normally this change is too small to detect directly but a technique known as surface plasmon resonance has the required sensitivity and could be applied to observe neuronal activity. This would provide a method of recording action potentials non-invasively and thus for extended periods of time. Furthermore, because it is an optical technique, a large area can be observed and therefore the action potential activity of a whole network of neurons could be monitored.The aim of this research proposal is to develop a system that will allow the action potential activity of an entire network of neurons to be observed using surface plasmon resonance imaging. A small network of cultured neurons will be grown on the surface of a sensor. Light will illuminate this sensor surface to induce surface plasmons and any small changes to this light that occur during an action potential will be monitored with a fast custom made camera.Using this system to investigate network action potential activity from a small culture of neurons will allow us to develop models of information processing in the more complex networks found in living brains. Ultimately these models will lead to treatments to correct the instabilities that underlie many brain diseases and disorders.