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Thesis Defense: Functions of Mediodorsal Thalamic Astrocytes in Cue-Based Learning

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Katie Marschalko
Thesis Defense

Functions of Mediodorsal Thalamic Astrocytes in Cue-Based Learning

Katie Marschalko

Graduate Student, Translational Biology, Medicine, and Health
Graduate Research Assistant, Howe Lab,  School of Neuroscience, College of Science, Virginia Tech
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About this Dissertation

To successfully navigate daily life, organisms must be able to identify stimuli that are predictive of beneficial outcomes. A key thalamic nucleus involved in this process is the mediodorsal thalamus (MD), which bidirectionally communicates with the prefrontal cortex, facilitating cognitive and decision-making functions. Despite the MD's involvement in higher-order relays, the precise mechanisms underlying its astrocytic activity, its contribution to synaptic plasticity, and the subsequent effects on cognitive processing remain poorly understood. Emerging data highlights the pivotal role of astrocytes in regulating synaptic transmission, with astrocytic calcium activity being linked to gliotransmitter release. Abnormalities in astrocytic calcium activity have been found to impair learning and memory, thus insights into their mechanism during cognitive processes in the MD could reveal novel targets for investigating cognitive disorders. In this study, Marschalko, mentored by Dr. Howe and Dr. Fox, investigated astrocytic activity during a cue-based learning task, uncovering notable differences in the timing of astrocytic calcium release between early and late stages of the task. To investigate plasticity-related changes between early and late stages, the colocalization of astrocytes, glutamatergic nerve terminals, and astrocyte glutamate transporter proteins will be examined. The research found that MD astrocytic calcium activity responds to the initial cue and the reward, suggesting that this activity mediates the temporal dynamics of synaptic plasticity, influencing how thalamic circuits adjust to both cues and outcomes during learning.

More About the Candidate and Project

Education

Virginia Tech, Translational Biology, Medicine, and Health, M.S. Candidate

Virginia Tech, B.S., Clinical Neuroscience

Training

Graduate Research Assistant, Howe Lab, Virginia Tech; Fox lab, Fralin Biomedical Research Institute at VTC

Mentors

William "Matt" Howe, Ph.D., Assistant Professor, School of Neuroscience, College of Science, Virginia Tech

Committee Members

  • Alexandra DiFeliceantonio, Ph.D., Assistant Professor, Fralin Biomedical Research Institute at VTC
  • Michael Fox, Ph.D., Dean, College of Natural Sciences, University of Massachusetts, Amherst
  • Sarah Clinton, Ph.D., Health Sciences Associate Vice President for Planning and Strategy, Fralin Biomedical Research Institute at VTC

Publications

Runyon, K., Bui, T., Mazanek, S., Hartle, A., Marschalko, K., & Howe, W. M. (2024). Distinct cholinergic circuits underlie discrete effects of reward on attention. Frontiers in Molecular Neuroscience, 17, 1429316.

Conference Presentations

Katie Marschalko, Nick Damiano, Emily York, Alec Hartle, Kelly Runyon, W. Matt Howe (October, 2024).Ca+2 dynamics in mediodorsal thalamic astrocytes track cue-reward learning. Poster presented at the Society for Neuroscience Meeting, Chicago, Illinois

Runyon, K., Greenway, A., Mazanek, S., Sallee, C., Hartle, A., & Marschalko, K., Howe, W.M. (November 2022). Neuromodulation of a thalamo-cortical cue detection circuit. Poster presented at the Society for Neuroscience Meeting, San Diego, California.

Hartle, A., Sisco, J., Marschalko, K., Runyon, K., DiFeliceantonio, A., Howe, M. (November 2021). Unique effects of macronutrient combinations on dopamine release and food choice. Talk presented at the Society for Neuroscience Meeting, Virtual.

Hartle, A., Sisco, J., Runyon, K., Marschalko, K., DiFeliceantonio, A., Howe, M. (July 2021). Macronutrient modulation of food reward. Poster presented at the Society for the Study of Ingestive Behavior Meeting, Virtual.

Poster Presentations

Marschalko, K., Tatera, W., Sallee, C., Damiano, N., Howe, M. (December, 2023) The Impacts of Satiety States on the Dorsolateral Parabrachial to Central Amygdala Cholinergic Circuit. Presented in the Fralin Biomedical Research Institute for the Translational Biology Medicine and Health Graduate Program.

Tatera, W., Sisco, J., Marschalko, K., Howe, M. (February, 2022) Function of Cholinergic Projections from the Lateral Parabrachial Nucleus to Central Amygdala. Presented in Life Sciences 1 for the Translational Biology Medicine and Health Graduate Program.

Blankenship, M., Haueis, J., Marschalko, K., Russell, N., Solomon, B., Impacts of Soil pH Change in Genetically Modified Arabidopsis thaliana Plants. Presented at Moss Arts Center.

  • 2nd place Hokie Pitch "Shark Tank" Competition award