The functional connectivity of the brain evolves throughout the life of every individual. These changes, often referred to as neuroplasticity, can be impacted by a wide range of variables from diseases to eating a favorite dessert. How can these changes be modulated to treat neurological diseases and disorders such as post traumatic stress and major depressive disorder? My colleagues and I are intrigued with the prospects of neuromodulation as a therapeutic for abnormal brain connectivity and network dynamics, leading me to the question “At what rate do these connections accumulate and decay with optogenetic modulation; Optogenetics, a technique that uses light to activate or inhibit genetically targeted neurons, offers high cell-specificity and temporal resolution that allows us to zoom into the network dynamics and find more finely tuned results that can help in the development of neuromodulation therapies. I plan to use both single site and paired-pulse optogenetic inhibition to gain a clearer understanding of how functional connectivity behaves during and after repeated modulation periods followed by extended recordings of spontaneous activity with no modulation. By analyzing the pairwise coherence of the local field potentials collected using electrocorticographic recordings in non-human primates, I anticipate seeing targeted changes in functional connectivity when comparing before and after each inhibition session. By analyzing the rate of change in connectivity I plan to understand the timeline of neuroplasticity following optogenetic modulation, thus informing the development of future neuromodulation therapies. This research could have a profound impact on the future therapeutic paradigms for neurological and neuropsychiatric disorders that can accelerate recovery for individuals with these conditions.

Non-Human Primates (NHPs) have gained importance in neural engineering preclinical studies as their brains are relevant models to investigate and better understand neural function. The Yazdan lab uses optogenetics to control neuronal activity in order to develop stimulation-based therapies for neurological disorders such as stroke. These experiments require the implantation of various devices such as headposts, cranial chambers, electrode arrays, and optical windows. The use of head posts and cranial chambers requires customization to the curvature of the skull prior to implantation in order to prevent gaps that could introduce complications, including infection or decreased stability. Using an in-house method of NHP neurosurgery preparation that processes MRI data, we can develop 3D brain and skull models. This technique has allowed for chambers to be customized and implanted chronically in two NHPs. My project builds off of this implementation by creating custom chambers for future implantation surgeries and designing custom-fit headposts, which had never been done before. In order to design these components, I extracted the skull and brain using custom Matlab code which allowed for the craniotomy location to be determined and provided a footprint for the chamber and headpost implants. I then imported the skull extraction into a design software where the chambers and headposts could be built off of to ensure a tight fit to the skull. With the components designed, I will 3D print the brain, skull, chamber, and headpost to be assembled together. This platform will simulate the surgical and experimental setup, which provides a template for various experimental components to be modified and tested. It will provide a simple and affordable solution for neurosurgical planning, reducing in-surgery and in-experiment complications. This model's versatility, ease of use and low cost allow for further expansion to other labs and to a wider scope of surgeries.