Development of a brain based, electronic auditory prosthesis: A behavioral study of optimal electrode location and stimulus parameters
Abstract
Intracortical microstimulation (ICMS) of primary sensory regions of the brain uses brief pulses of electrical energy delivered through microscopic electrodes in order to artificially activate networks of neurons creating sensory illusions in the stimulated individual. This ability to generate artificial sensations makes ICMS a compelling platform for the development of sensory prostheses for the blind, paralyzed and deaf. Unfortunately, fundamental questions regarding the optimal stimulation parameters that would form the basis for such a device have not been addressed in a systematic and behaviorally relevant way leading researchers to select stimuli based on ad hoc assumptions and arbitrary historical standards. This work summarizes a series of behavior experiments performed in rats that had been trained to detect auditory and then electrical stimuli delivered through microelectrodes implanted in the primary auditory cortex. These experiments were designed to answer the following three questions: 1) What is the optimal stimulation waveform? 2) What is the maximal useful pulse rate? 3) What is the best cortical depth for stimulation? The present results suggest the following answers: 1) biphasic, charge balanced, symmetric, cathode leading pulses with of duration of ~ 100 microseconds per phase without phase delay, 2) 80 pulses-per-second, and 3) cortical layers V&IV1. These three fundamental findings could form the basis of a brain based electronic auditory prosthesis which might one day help deaf patients hear and understand speech.
Degree
Ph.D.
Advisors
Otto, Purdue University.
Subject Area
Neurosciences|Behavioral psychology|Biomedical engineering
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