High-resolution spatiotemporal analysis of harmaline-induced tremor and inferior olive activity in living mice

2022 Fiscal Year Research-status Report

• Project/Area Number: 22K06478
• Research Institution: Okinawa Institute of Science and Technology Graduate University
• Principal Investigator: ウーシサーリ マルリカ・ヨエ 沖縄科学技術大学院大学, 神経活動リズムと運動遂行ユニット, 准教授 (30799656)
• Project Period (FY): 2022-04-01 – 2025-03-31
• Keywords: tremor / harmaline / motion capture / calcium imaging / in vivo

Outline of Annual Research Achievements

In the past year, our dedicated research team has made noteworthy progress in elucidating the kinematic and neuromotor mechanisms of tremor-related disorders. We have successfully initiated a project to determine safe conditions for viral expression of GCamP6 in the inferior olive (IO), which plays a critical role in understanding harmaline-induced tremor in mice. This work's findings will be presented at the esteemed JNS conference in Sendai, August 2023. Concurrently, we expanded our experimental setup to assess harmaline-induced tremor in mice performing various motor tasks, such as high-speed locomotion, balancing, and 3D space exploration. Furthermore, we have integrated these intricate naturalistic behavior tasks with simultaneous recording of cerebellar nuclear activity, completing the initial full batch of experiments in April 2023. Our progress demonstrates our unwavering commitment to overcoming challenges in studying tremor-related disorders.

Current Status of Research Progress

3: Progress in research has been slightly delayed.

Reason

At present, our research is focused on meticulously analyzing the results from the initial batch of experiments, which combined motion capture with cerebellar nuclear activity recordings. We have discovered that high expression levels of GCamP6 in the IO can cause motor disturbances, prompting us to take a detour and establish safer viral expression parameters. In response, we are employing a novel experimental workflow, including systematic quantitative analysis of motor performance, expression level assessment, and neuronal damage indexing using quantitative light-microscope-based morphometry. By addressing these unexpected findings, we ensure that our research remains robust and reliable, allowing us to continue making progress in understanding the pathology and neuromechanics of tremor disorders.

Strategy for Future Research Activity

In the upcoming year, we plan to continue refining our research approach and develop advanced analytical methodologies, including the application of dynamic systems theory. This will enable us to establish a link between changes in neuronal activity caused by harmaline and the precise perturbations of movement observed in the mouse model. By doing so, we aim to deepen our understanding of the kinematic and neuromotor mechanisms underlying tremor-related disorders. Furthermore, we will work on incorporating the lessons learned from our experience with GCamP expression levels and motor disturbances to optimize our experimental workflow. Our ultimate goal is to contribute to the development of novel diagnostic and therapeutic strategies for tremor-related disorders. As we move forward, we remain committed to overcoming challenges and furthering our knowledge in this critical area of research, ultimately benefiting patients suffering from tremor-related disorders and the global scientific community.

Causes of Carryover

Due to global delivery problems, we could not receive some shipment by time in March, even though the order was placed in January (and the company was claiming one-week-shipping). We had to cancel that order and re-order in April (glassware for brain sample manipulation).