{"333731":{"#nid":"333731","#data":{"type":"event","title":"Neural Engineering Center \u0026 Young Innovators in Biomedical Engineering Seminar","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003E\u0022\u0022On the Therapeutic Mechanisms of Deep Brain Stimulation for Parkinson\u0027s Disease: Why High Frequency?\u0022\u003Cbr \/\u003E\u003Cbr \/\u003ESridevi V. Sarma, PhD\u003Cbr \/\u003E\u003C\/strong\u003E\u003Cstrong\u003EJohns Hopkins University\u003Cbr \/\u003E\u003C\/strong\u003E\u003Cstrong\u003EAssistant Professor, Department of Biomedical Engineering\u003Cbr \/\u003E\u003C\/strong\u003E\u003Cstrong\u003EInstitute for Computational Medicine\u003Cbr \/\u003E\u003Cbr \/\u003E\u003C\/strong\u003EDeep brain stimulation (DBS) is clinically recognized to\u0026nbsp;treat movement disorders in Parkinson\u0027s disease (PD), but its\u0026nbsp;therapeutic mechanisms remain elusive. One thing is clear though: high\u0026nbsp;frequency periodic DBS (130-180Hz) is therapeutic, while low frequency\u0026nbsp;DBS is not therapeutic and may even worsen symptoms. So, what is so\u0026nbsp;special about high frequency? In this talk, we address this question\u0026nbsp;by discussing our viewpoint supported by recent results from our key\u0026nbsp;studies of the thalamo-cortical-basal ganglia motor loop. First, thalamic cells play a pivotal role in performing movements by\u0026nbsp;selectively relaying motor-related information back to cortex under\u0026nbsp;the control of modulatory signals from the basal ganglia (BG). Through\u0026nbsp;computational models of the thalamic cells, bifurcation analysis, and\u0026nbsp;single unit recordings from healthy primates and PD patients engaged\u0026nbsp;in motor tasks, we show that (i) there is a set of BG signals (\u0022Proper\u0026nbsp;Relay Set\u0022, PRS), under which the thalamic cells can reliably relay\u0026nbsp;the motor commands, and that (ii) the BG signals belong to the PRS in\u0026nbsp;healthy conditions but are outside the PRS under PD conditions. Then, we use a detailed computational model of the motor loop under PD\u0026nbsp;conditions to study the effects of DBS on the BG signals projecting to\u0026nbsp;the thalamic cells. We show that high frequency periodic DBS steers\u0026nbsp;the BG signals back to the PRS while lower frequency regular DBS and\u0026nbsp;irregular DBS do not. Furthermore, through numerical simulation of the\u0026nbsp;model we show that DBS pulses evoke inputs that propagate through the\u0026nbsp;motor loop both orthodromically (i.e., forward) and antidromically\u0026nbsp;(i.e., backward) and fade away within a few milliseconds, thus having\u0026nbsp;little effects on the BG signals. However, when the latency between\u0026nbsp;consecutive DBS pulses is small (i.e., DBS is high frequency) and\u0026nbsp;constant over time (i.e., DBS is periodic), then orthodromic and\u0026nbsp;antidromic effects can overlap within the loop and result into a\u0026nbsp;strong, long-lasting perturbation that ultimately drives the BG signals.\u0026nbsp;Taken together, these results provide a holistic, albeit abstract,\u0026nbsp;view of motor control in healthy and PD conditions, account for the\u0026nbsp;neural mechanisms of therapeutic DBS, and suggest that the merit of\u0026nbsp;DBS likely depend on the closed-loop nature of the\u0026nbsp;thalamo-cortical-basal ganglia system.\u003C\/p\u003E\u003Cp\u003EFaculty hosts -\u0026nbsp;\u003Ca href=\u0022mailto:crozell@gatech.edu\u0022\u003EChristopher J. Rozell, PhD\u003C\/a\u003E, and \u003Ca href=\u0022mailto:garrett.stanley@bme.gatech.edu\u0022\u003EGarrett B. Stanley, PhD\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThere will be a Neural Engineering Center reception to follow\u0026nbsp;in the BME Atrium.\u003C\/em\u003E\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EThe Wallace H. Coulter Department of Biomedical Engineering hosts special guests and visitors throughout the year. These seminars are open to all faculty and students.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"\u0022On the Therapeutic Mechanisms of Deep Brain Stimulation for Parkinson\u0027s Disease: Why High Frequency?\u0022 - Sridevi V. Sarma, PhD - Johns Hopkins University"}],"uid":"27960","created_gmt":"2014-10-14 10:36:36","changed_gmt":"2017-04-13 21:21:26","author":"Chris Calleri","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2014-10-28T12:00:00-04:00","event_time_end":"2014-10-28T13:30:00-04:00","event_time_end_last":"2014-10-28T13:30:00-04:00","gmt_time_start":"2014-10-28 16:00:00","gmt_time_end":"2014-10-28 17:30:00","gmt_time_end_last":"2014-10-28 17:30:00","rrule":null,"timezone":"America\/New_York"},"extras":["free_food"],"hg_media":{"333711":{"id":"333711","type":"image","title":"Sridevi V. Sarma, PhD","body":null,"created":"1449245133","gmt_created":"2015-12-04 16:05:33","changed":"1475895044","gmt_changed":"2016-10-08 02:50:44","alt":"Sridevi V. Sarma, PhD","file":{"fid":"200433","name":"sarmapecase.jpg","image_path":"\/sites\/default\/files\/images\/sarmapecase_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/sarmapecase_0.jpg","mime":"image\/jpeg","size":50362,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/sarmapecase_0.jpg?itok=JWHxjlM-"}}},"media_ids":["333711"],"groups":[{"id":"1254","name":"Wallace H. Coulter Dept. of Biomedical Engineering"},{"id":"1292","name":"Parker H. Petit Institute for Bioengineering and Bioscience (IBB)"}],"categories":[],"keywords":[{"id":"106311","name":"BME Seminar"},{"id":"248","name":"IBB"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1795","name":"Seminar\/Lecture\/Colloquium"}],"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\u003EFaculty hosts -\u0026nbsp;\u003Ca href=\u0022mailto:crozell@gatech.edu\u0022\u003EChristopher J. Rozell, PhD\u003C\/a\u003E, and\u0026nbsp;\u003Ca href=\u0022mailto:garrett.stanley@bme.gatech.edu\u0022\u003EGarrett B. Stanley, PhD\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}