Studying the effects of different anesthetics on quasi-periodic patterns in rat fMRI

Functional connectivity is defined as how regions of the brain are connected through similar patterns of activity. Quasi-periodic patterns (QPPs), semi-repeating patterns of activity throughout the brain during rest, are one measure of brain activity that has been found to contribute to functional connectivity. However, it has been shown that functional connectivity can be affected by neurological diseases such as Alzheimer's disease. Neurological diseases are often studied in rodent models when they are under anesthesia, which is known to change brain activity. Therefore, in this project, we aimed to observe the effects of three commonly used rodent anesthetics—isoflurane, dexmedetomidine, and a combination of both—on QPPs. This work was done by analyzing previously acquired functional MRI (fMRI) data from eight male Sprague Dawley rats using a 9.4 T MRI scanner. We then used a modified MATLAB script to run analyses on the imaging data. We hypothesized that dexmedetomidine and isoflurane would have inverse effects on the frequency of QPPs and QPP strength. This project has shown that these anesthetics may have different effects on QPP signals and that researchers should be aware of these potential effects when incorporating them into rodent disease model studies. Some of these effects may be at a greater level of strength or level of activation when compared to QPP results from other anesthetics. Other effects may be the result of variability between individual rats and how this may impact their results.