Anesthetic Effects on Neuronally-based Resting-state Functional Connectivity (S43.008).

Area of Science:

• Neuroscience
• Anesthesiology
• Medical Imaging

Background:

• Resting-state functional connectivity (RSFC) measures correlated brain signals during rest.
• fMRI in humans tracks blood-oxygen-level-dependent (BOLD) signals for RSFC.
• Anesthetic effects on neuronal signals in mice are less understood than hemodynamic effects.

Purpose of the Study:

• Investigate how tribromoethanol, isoflurane, and ketamine/xylazine impact neuronally and hemodynamically based functional connectivity.
• Compare the effects of different anesthetics on brain activity and blood flow.
• Determine the optimal anesthetic for studying functional connectivity in mice.

Main Methods:

• Used Thy1-GCaMP6f mice with genetically encoded calcium indicators to monitor neuronal activity.
• Employed GCaMP fluorescence and optical intrinsic signal imaging.
• Administered tribromoethanol, isoflurane, and ketamine/xylazine sequentially to each mouse in a randomized order.
• Calculated bihemispheric connectivity index (BCI) and z-transformed correlation coefficients.

Main Results:

• Tribromoethanol demonstrated the highest bihemispheric connectivity index (BCI) for both neuronal and hemodynamic signals.
• Tribromoethanol's BCI was significantly higher than ketamine/xylazine and isoflurane.
• Ketamine/xylazine showed reduced variability and the highest correlation between neuronal and hemodynamic signals.
• All anesthetics exhibited high correlations between GCaMP and oxy-hemoglobin signals.

Conclusions:

• Tribromoethanol optimized BCI more effectively than ketamine/xylazine and isoflurane.
• Isoflurane exhibited significant variability in functional connectivity measures.
• Anesthetic selection is crucial for accurate functional connectivity studies in mice.