Study for neuromodulation technique using plasmonics of gold nanorod and near infrared laser

Abstract

This dissertation presents novel stimulation strategy for modulation of neural activity. The ultimate goal of neuroscience is to understand how the neural activities operate brain functions, which is crucial for the purpose of brain disorder treatment. To decode the function of neurons and their activities, neuromodulation technique that can precisely control the neural activity is essential. Especially, the inhibitory tool is valuable to investigate the role of specific neurons in complex circuits. However, efficient inhibition technique has been lacked, and it is hard to suppress the activity using a conventional approach such as electrical stimulation. Although optogenetical method provides the reliable loss-of-function from target neurons, requirement of genetic modification impedes the clinical application. Here, main purpose of this dissertation is to develop the stimulation technique that can inhibit the electrical activity of unmodified neurons. This study utilized the unique property of gold nanorod that is photothermal conversion characteristics upon near infrared illumination. The photothermal effect of gold nanorods affected the neural excitability, resulting in clear inhibition phenomena. Depending on the strength of photothermal stimulation, firing rates of neurons and signal transmission along with neurites were modulated and blocked, respectively. And further studies demonstrated that the thermosensitive-potassium channel was involved in the inhibition. This photothermal stimulation was sufficient to inhibit the large network to single neuron activity using one-photon illumination, and this technique could be simply integrated with conventional neurodevices to achieve the multifunctional modality. The results in this dissertation are expected to contribute to future researches and disease therapeutics by wide adoptions in the field of neuroscience.