Intracortical Microstimulation of the Thalamocortical Auditory Pathway

Ryan Verner (Dr. Ed Bartlett, advisor)

Abstract: Despite the success of modern neuroprosthesis and the breadth of their applications, adoption of these technologies into medicine has been slow.  A contributing factor to this hesitation is the potential danger of long-term faradaic electrical stimulation of nervous tissues.  In order to reach detectable levels of stimulation in behavioral experiments, many animal models receive levels of stimulation which result in reduction-oxidation reactions in the surrounding tissue.  The current technique to mitigate this effect is using biphasic, charge-balanced square pulses at high frequencies in order to capture harmful reaction products and potentially reverse the reaction entirely.  An unexplored technique is the development of electrode designs which utilize constructive potential field superposition to stimulate larger populations of neurons at lower charge densities.  Another promising implication of this technique is the ability to control the spatiotemporal dynamics of the potential field, thereby exciting more specific populations of neurons than is currently possible with off-the-shelf electrodes.  Through modeling in MATLAB and simulations in HFSS, we propose and validate several innovative electrode designs to achieve these goals.

Stiffness characterization in biological materials based on deformation imaging and topology optimization

Luyao Cai (Dr. Corey Neu, advisor)

Abstract: Medical imaging modalities enable the nondestructive measurement of deformation and internal tissue mechanics. One specialized Magnetic resonance imaging (MRI) technique, termed displacements under applied loading by MRI (dualMRI), was developed to measure displacements and strain in musculoskeletal tissues, hydrogels, and engineered constructs. However, displacement and strain information does not directly describe spatial distributions of tissue stiffness, which is critical to the understanding of disease progression. In order to achieve stiffness mapping nondestructively in explanted tissues or even in living animals or humans in vivo, here we proposed an inverse modeling approach to map the internal stiffness from image-based displacements measured in engineered agarose constructs as an idealized system. In this abstract, forward simulations were performed on materials with known properties and boundary conditions. With different level of noise added, the error associated with the relative stiffness mapping technique was studied. Additionally, experimental data from two agarose plugs with heterogeneous mechanical properties were analyzed. The significance and potential of this approach was highlighted for the description of tissue degeneration, repair, and complex material properties.

***Bring your lunch to seminar – BMEGSA will provide snacks and drinks***

(Also available via WebEx meeting in SL220A at IUPUI)