Research, G. Gerling, Ph.D. - University of Virginia

Gregory J. Gerling, Ph.D.

Assistant Professor

Systems and Information Engineering

gregory-gerling virginia edu

News Updates


	Lesniak conference paper accepted to IEEE EMBC July 8, 2009 Lesniak, DL, Wellnitz, SA, Gerling, GJ, and Lumpkin, EA, Statistical analysis and modeling of variance in the SA-I mechanoreceptor response to sustained indentation (accepted for IEEE EBMS Engineering in Medicine and Biology Conference, Minneapolis, MN September 6, 2009) Abstract: The slowly-adapting type I mechanoreceptor (SA-I) exhibits variability in its steady-state firing rate both within an afferent upon repeated stimulation and between afferents. Additionally, inter-spike intervals of the SA-I are extremely variable during this steady-state firing. While variability of the SA-I response has been noted previously, the work presented herein provides a finer analysis of the impact of force and fiber on the SA-I response. Specifically, we test two hypothesis, that 1) fiber-to-fiber variation will significantly impact firing rate over the range of applied forces, and that 2) fiber-to-fiber variation will significantly impact the coefficient of variation (CV) of inter-spike intervals over the range of applied forces. Utilizing an ex vivo skin nerve preparation in the mouse, experiments were conducted with six SA-I fibers from five mice, and with compressive stimuli with force magnitudes up to 9.59 mN. We found fiber to significantly impact both firing rate and CV. These findings motivated the construction of a generalized input (force) - output (firing rate) model composed of a baseline response profile and a multiplicative fiber sensitivity factor. This work will inform future efforts to attribute variability to differences in skin, neuron, and receptor properties, and will contribute to the understanding of how much variability is acceptable in systems designed to provide tactile feedback to the nervous system.

	Paper accepted by Applied Bionics and Biomechanics May 22, 2009 SA-I mechanoreceptor position in fingertip skin may inpact sensitivity to edge stimuli by Gregory Gerling was accepted by Applied Bionics and Biomechanics. Abstract: Background: The skin plays a role in conditioning mechanical indentation into distributions of stress/strain that mechanoreceptors convert into neural signals. Solid mechanics methods have modeled the skin to predict the in vivo neural response from mechanoreceptors. Despite their promise, current models cannot explain the role that anatomical positioning and receptor organ morphology play in producing differences in neural response. This work hypothesizes that the skin's intermediate ridges may help explain, in part, the sensitivity of slowly adapting type I (SA-I) mechanoreceptors to edge stimuli. Method: Two finite element models of the fingertip were built, validated, and used to analyze the functionality of the intermediate ridges. One of the 2D, cross-sectional models included intermediate ridges, while the second did not. The analysis sought to determing if intermediate ridges a) increase the magnitude of strain energy density were found near the SA-I location and b) help differentiate one 2.0 mm indenter from two 0.5 mm wide indenters with a 1.0 mm gap. Results: Higher concentrations of strain energy density were found near the tips of the intermediate ridges, the anatomical location that coincides with the SA-I receptors. The first result suggested that the location of the SA-Is in the stiffer epidermal tissue helps magnify their response to edge stimuli. The second result was that both models were equally capable of predicting the spatial structure within the in vivo neural responses, and therefore the addition of intermediate ridges did not help in differentiating the indenters. Conclusions: The finding, a 15-35% increase in response when the sampling point lies within the stiffer tissue at the same depth, seeks to inform the positioning of force sensors in robotic skin substrates.

	Capstone team wins best paper in the Human Factors in Healthcare Track at the 2009 SIEDS conference May 18, 2009 Everett, KA, Exon, RE, Rosales, SH, Gerling, GJ, Virtual Reality Interface to Provide Point Interaction and Constriction to the Finger (SIEDS Conference, 2009, Charlottesville, VA, pp. 203-207) Abstract: Virtual reality (VR) simulation of tube thoracostomy may improve the procedural training for medical and nursing students. Current VR simulators, however, do not provide tactile feedback, which is essential for enabling certain tasks (e.g., surface palpation to identify rib location, blunt dissection for access to pleural space surrounding the lungs, and finger sweep to confirm location in the pleural space). This work develops a physical apparatus that provides users with point feedback at the fingertip when palpating an external surface and a sensation of constriction around the finger during insertion into a body. The physical apparatus is composed of two components that separately control the constriction on the tip and middle of the finger. Each constriction component is made of two nylon casings coated with a silicone-elastomer that enclose about the top and bottom of the finger. DC gearhead motors control the magnitude of pressure in proportion to feedback from force transducers embedded in the silicone-elastomer. The device is intended to communicate with a virtual environment (written in H3D). The apparatus augments traditional stick-based force feedback and should enhance the learning of tactile tasks in tube thoracostomy.

	Paper with Lumpkin Lab, Baylor Col. of Medicine accepted by Science May 2, 2009 Maricich, S.M., Wellnitz, S.A., Aislyn M., Nelson, A.M., Lesniak, D.R., Gerling, G.J., Lumpkin, E.A., and Zoghbi, H.Y., "Merkel Cells are Essential for Light Tough Responses." The article can be seen here.

	Bill Carson presents on device built to measure prostate stiffness May 1, 2009 Bill Carson was one of 7 individual finalists in the 2009 Spring Undergraduate Research and Design Symposium at the University of Virginia. His talk was titled "Using spherical indentation to compare the material properties of synthetic and ex vivo prostate tissue in a clinical setting." His involvement at the conference was written up in a story by the Cavalier Daily which can be seen here.

	Journal paper by Daine Lesniak accepted by Mathematical Biosciences April 1, 2009 Mathematical Biosciences accepted the journal paper "Predicting SA-I mechanoreceptor spike times with a skin-neuron model" written by Daine R. Lesniak and Gregory J. Gerling. Abstract: Slowly adapting type I (SA-I) mechanoreceptors encode the edges and curvature of touched objects by generating neural spikes in response to indentation of the skin. Beneath this general input-output relationship, models are of great utility for understanding the sub-processes, as SA-I transduction sites are inaccessible to whole-cell recording. This work develops and validates a SA-I skin-receptor model that combines a finite element model of skin mechanics, a sigmoidal function of transduction, and a leaky integrate-and-fire model of neural dynamics. The model produced a R2=0.80 goodness of fit between predicted and observed firing rates for 3 mm and 5 mm grating stimuli. In addition, modulation indices of predicted firing rates for 3 mm and 5 mm gratings are 0.46 and 0.59 respectively, compared to the 0.71 and 0.72 found in vivo. An analysis of predicted first spikes indicates their latency may also be enhanced by edges, as edge proximity shortened first spike latencies by 26.2 and 41.8 ms for the 3 mm and 5 mm gratings, respectively. The model described here bridges the gap between those models that transform sustained indentation to firing rates and those that transform vibration to spike times.

	Paper published on a simulator for training clinical prostate exams February 26, 2009 Greg Gerling, Sarah Rigsbee, Reba Childress, and Marcus Martin published their research titled The Design and Evaluation of a Computerized and Physical Simulator for Training Clinical Prostate Exams in IEEE Transactions on Systems, Man, and Cybernetics – Part A: Systems and Humans.

	Cavalier Daily Article: New Simulator Provides Unique Practice January 27th, 2009 "An ongoing collaboration involving the University's Nursing, Medicine and Engineering schools has resulted in the creation of a simulator designed to help fight prostate cancer. The simulator, known as the Virginia Prostate Exam Simulator, is a human patient simulator created by professors, undergraduate students and graduate students that is designed to help teach students how to effectively detect prostate cancer." Click here to view the entire Cavalier Daily article on the prostate cancer simulator designed by our team.

	NBC 29 Interview: Simulator Helps UVA Doctors Detect Cancer January 26th, 2009 "The University of Virginia is home to a one of a kind, high-tech teaching tool training doctors and nurses to diagnose prostate cancer. The Virginia Prostate Examination Simulation (VPES) uses a prostate made of silicone full of tiny water balloons that act as tumors. Sensors tell with the student finds a tumor, allowing professors to give instant feedback to students giving the exam. Doctors say the simulations are vital to help rising medical professionals save lives in the future." Click here to view the entire NBC 29 interview on the prostate cancer simulator designed by our team.

	Two papers presented at AMIA conference November 10, 2008 Daine Lesniak and Michael Cary presented two papers at the AMIA Conference: An Engineering Work Analysis to Patient Falls in the Nursing Domain (Michael Cary) and Modeling the Data Transformations Underlying Touch Sensation to Further Tactile Feedback in Neural Prosthesis (Daine Lesniak).

	Journal paper accepted by IEEE SMC, Part A October 24th, 2008 Rigsbee, S., Gerling, G.J., Moyer Childress, R. and Martin, M. L., "The Design and Evaluation of a Computerized Physical Simulator for Training Clinical Prostate Palpation Skills." (in press, IEEE Transactions on Systems, Man, Cybernetics, Part A)

	Six students participated at Virginia Tech HFES Student Conference October 15th, 2008 Daine Lesniak, Miki Wang, Elmer Kim, Angela Lee, Isabelle Rivest and Bill Carson participated at the Virginia Tech Human Factors and Ergonomics Society Student Conference in Blacksburg, Virginia.

	Miki Wang presents paper at HFES conference in NYC September 25th, 2008 Miki Wang presented a paper on the characterization of finger palpation. Wang, M., Gerling, G.J., Moyer Childress, R., and Martin, M.L., "Characterizing Finger Palpation in the Detection of Prostate Cancers and Abnormalities" (Human Factors and Ergonomics Society, 2008, New York City, NY).

	Gerling gives talk at Department of Industrial and Systems Engineering (ISE) at the University of Buffalo September 15, 2008

	Charlottesville Community Health Fair July 26th, 2008 Greg Gerling participated in the Charlottesville Community Health Fair on Saturday along with graduate students Miki Wang and Leigh Baumgart.

	Lesniak presents work at National Library of Medicine July 8th, 2008 Daine Lesniak presented work "Modeling the Data Transformations Underlying Touch Sensation to Further Tactile Feedback in Neural Prosthesis" at the National Library of Medicine Informatics Training Conference in Bethesda, Maryland.

	UVa Today story on Michael Cary May 21st, 2008 Michael Cary is working with Greg Gerling on a project under the National Library of Medicine diversity award to apply systems engineering to analyze the nursing problem of patient falls. Click here to read the entire UVa Today article on Michael Cary.

	Invited Presentation at UVa Medical School April 24th, 2008 Marcus Martin, Greg Gerling, Reba Childress, Ninghuan Wang, Sarah Risgbee, Isabelle Rivest, and Angela Lee presented at the UVa Medical School on A Physical Simulator for Training Clinical Palpation Skills in Exams of the Prostate Gland, Clinical Connections Session

	Invited Talk at Old Dominion University February 29th, 2008 Greg Gerling spoke at Old Dominion University on Neural Prosthetic Touch and Simulation for Medical/Surgical Tasks.

	Grant from DARPA received February 29, 2008 Greg Gerling receives a grant from DARPA entitled "Enabling the Sense of Touch: Mimicking Responses from Single-Receptors and Optimizing Populations." Dr. Gregory Gerling , PI, and Dr. Ellen Lumpkin (Baylor School of Medicine, Houston, Texas), Co -I, receive notice of award from DARPA for their proposal, "Enabling the Sense of Touch: Mimicking Responses from Single-Receptors and Optimizing Populations." Graduate students, Daine Lesniak and Matt Wagner, in particular, contributed. The grant is for approximately $500,000 and will run for two years starting in June 2008.

	Receive grant for prostate cancer simulation work November 9, 2007 Greg Gerling, PI, along with Dr. Reba Childress (Nursing) and Dr. Marcus Martin (Emergency Medicine) receive notice of award from the Congressional Directed Medical Research Program for their proposal "The Development of Prostate Palpation Skills through Simulations Training may Impact Early Detection of Prostate Abnormalities and Early Management." The grant is for approximately $391,000 and will run for three years starting in May 2008.

	Article published in IMPACT on Gerling Fall 2007 An article was published in IMPACT (UVA Engineering) on Greg Gerling and his lab. The story included a photo of Greg Gerling and a feature on graduate student Daine Lesniak. Click here to view the entire IMPACT article on the intersection of people and computers.

	Invited Talk at Navy Research Labs in Washington, D.C. September 24, 2007 Greg Gerling spoke at the Navy Research Lab in Washington, D.C. on Neural Prosthetic Touch and Simulation for Medical/Surgical Tasks.

	Granted provisional patent for computerized and physical simulator Greg Gerling along with Marcus Martin (Emergency Medicine) and Reba Childress (Nursing) were granted a provisional patent through the University of Virginia with the U.S. Patent Office for their computerized and physical simulator for training clinical prostate palpation skills.