Tuesday, July 23, 2013

Prof. Qi Wang (Biomedical Engineering, Columbia): July 24th

Title: Reading and Writing the Neural Code: Initial Steps toward Engineered Sensory Percepts
Abstract: The transformation of sensory signals into spatiotemporal patterns of neural activity in the brain is critical in forming our perception of the external world. Physical signals, such as light, sound, and force, are transduced to neural electrical impulses, or spikes, at the periphery, and these spikes are subsequently transmitted to the brain through various stages of the sensory pathways, ultimately forming the representation of the sensory world. Deciphering the information conveyed in the spike trains is often referred to as “reading the neural code”. On the other hand, prosthetic devices designed to restore lost sensory function, such as cochlear implants, rely primarily on the principle of artificially activating neural circuits to induce a desired perception, which we might refer to as “writing the neural code”. This requires not only significant challenges in biomaterials and interfaces, but also in knowing precisely what to tell the brain to do.

My talk will focus on three topics. First, I will talk about the control of peripheral tactile sensations. Specifically, I will discuss the synthesis of virtual tactile sensations using a custom-built, high spatiotemporal resolution tactile display, a device we designed to create high fidelity, computer-controlled tactile sensations on the fingertip similar to those arising naturally. Second, I will utilize a decoding paradigm to discuss the neural representations of tactile sensations and how they are encoded and transformed across early stages of processing in the somatosensory pathway. Finally, I will discuss the design of sub-cortical microstimulation to control cortical activation, using downstream cortical measurements as a benchmark of the fidelity of the surrogate signaling. Taken together, an understanding of how to read and write the neural code is essential not only for the development of technologies for translating thoughts into actions (motor prostheses), but also for the development of technologies for creating artificial sensory percepts (sensory prostheses).

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