{"293331":{"#nid":"293331","#data":{"type":"event","title":"PhD Defense Presentation- Michelle Kuykendal","body":[{"value":"\u003Cp\u003E\u003Cem\u003EAdvisor: Dr. Stephen P.\u0026nbsp; DeWeerth, School of Biomedical Engineering, Georgia Institute of Technology\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003ECommittee:\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EDr. Steve M. Potter, School of Biomedical Engineering, Georgia Institute of Technology\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EDr. Garrett Stanley, School of Biomedical Engineering, Georgia Institute of Technology\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EDr. Martha Grover, School of Chemical and Biomolecular Engineering, Georgia Institute of Technology\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EDr. Cameron McIntyre, Neural Engineering Center, Case Western Reserve University\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EClosed-loop optimization of extracellular electrical stimulation for targeted neuronal activation\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EWe have developed a high-throughput system of closed-loop electrical stimulation and optical recording that facilitates the rapid characterization of extracellular stimulus-evoked neural activity. The ability to selectively stimulate a neuron is a defining characteristic of next-generation neural prostheses. Greater stimulus control and differential activation of specific neuronal populations allows for prostheses that better mimic their biological counterparts.\u003C\/p\u003E\u003Cp\u003EIn our system, we deliver square current pulses using a microelectrode array; automated real-time image processing of high-speed digital video identifies the neuronal response; and a feedback controller alters the applied stimulus to achieve a targeted response. The system controller performs directed searches within the strength\u2013duration (SD) stimulus parameter space to build probabilistic neuronal activation curves. An important feature of this closed-loop system is a reduction in the number of stimuli needed to derive the activation curves when compared to the more commonly used open-loop system: this allows the closed-loop system to spend more time probing stimulus regions of interest in the multi-parameter waveform space, facilitating high resolution analysis.\u003C\/p\u003E\u003Cp\u003EThe stimulus-evoked activation data were well-fit to a sigmoid model in both the stimulus strength (current) and duration (pulse width) slices through the waveform space. The 2-D analysis produces a set of probability isoclines corresponding to each neuron-electrode pairing, which were fit to the SD threshold model described by Lapique (1907). We show that stimulus selectivity within a given neuron pair is reversible in the one-parameter search space by using multiple stimulation electrodes. Additionally, by applying simultaneous stimuli to adjacent electrodes, the interaction between stimuli alters the neuronal activation threshold. The interaction between simultaneous multi-electrode multi-parameter stimulus waveforms creates an opportunity for increased stimulus selectivity within a population.\u003C\/p\u003E\u003Cp\u003EWe demonstrate that closed-loop imaging and micro-stimulation technology enable the study of neuronal excitation across a large parameter space, which is requisite for controlling neuronal activation in next generation clinical solutions. \u0026nbsp;\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EPhD Defense Presentation-\u0022Closed-loop optimization of extracellular electrical stimulation for targeted neuronal activation\u0022- Michelle Kuykendal\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"\u0022Closed-loop optimization of extracellular electrical stimulation for targeted neuronal activation\u0022"}],"uid":"27917","created_gmt":"2014-04-25 14:41:32","changed_gmt":"2017-04-13 21:22:39","author":"Laura Paige","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2014-05-06T18:00:00-04:00","event_time_end":"2014-05-06T20:00:00-04:00","event_time_end_last":"2014-05-06T20:00:00-04:00","gmt_time_start":"2014-05-06 22:00:00","gmt_time_end":"2014-05-07 00:00:00","gmt_time_end_last":"2014-05-07 00:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"65448","name":"Bioengineering Graduate Program"}],"categories":[],"keywords":[],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78751","name":"Undergraduate students"},{"id":"78761","name":"Faculty\/Staff"},{"id":"174045","name":"Graduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003E\u003Ca href=\u0022mailto:Laura.Paige@bioengineering.gatech.edu\u0022\u003ELaura.Paige@bioengineering.gatech.edu\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}