Researchers in Korea and the USA have used a surface-plasmon resonance to optically detect activity in rat nerves. The approach offers a non-invasive, label-free way of probing neural signals.
Typically, an investigation of extracellular nerve signals involves applying some form of electrical stimulation to the nerve. However, the recorded signals often contain artefacts arising from the stimulating pulse. Optical recording, on the other hand, does not suffer from this drawback.
Usually fluorescent dyes are used to record the signals; however, these dyes are expensive, toxic and involve lengthy labelling processes. Shin Ae Kim and colleagues get round these problems by turning to surface-plasmon resonances. When an electrical impulse travels along a nerve, it causes physical changes that result in a change of refractive index. The corresponding rapid changes in the optical properties of the nerve can be picked up through the effect on a surface-plasmon resonance. Kim et al. demonstrate their approach in sciatic rat nerves that are adhered to a gold plasmonic surface in a recording device. Through simultaneous measurements of electrical and surface-plasmon-resonance signals, the optical responses are proven to be linked to in vitro neural activity. The next step is to apply the technique to in vivo settings.
참고 링크 : http://www.nature.com/nphoton/journal/v2/n5/full/nphoton.2008.57.html