Hemodynamic Signals Reshape Biological Inference in Widefield Calcium Imaging

Area of Science:

• Neuroscience
• Physiology
• Biophysics

Background:

• Widefield calcium imaging is crucial for studying cortex-wide neural dynamics.
• Fluorescence signals in this technique are susceptible to hemodynamic fluctuations (blood volume/oxygenation changes).
• The impact of hemodynamic correction on biological interpretations remains unclear.

Purpose of the Study:

• To investigate how hemodynamic correction reshapes inferences of cortical dynamics.
• To compare uncorrected and corrected signals across different mouse lines and analytical domains.
• To assess the influence of vascular signals under healthy and glioblastoma conditions.

Main Methods:

• Dual-wavelength imaging was employed across mouse lines (GCaMP6s, GCaMP6f, jGCaMP8m).
• Analyses included functional parcellation, connectivity, spectral structure, brain-behavior coupling, and network-state dynamics.
• Signals were systematically compared between uncorrected and corrected datasets.

Main Results:

• Correction reduced global functional connectivity and slow-frequency spectral power, while increasing network modularity.
• Vascular signals introduce organized variance, not just noise, affecting interpretations across analyses.
• In glioblastoma, correction revealed disease-specific alterations obscured in uncorrected data, highlighting tumor-associated vascular remodeling impacts.

Conclusions:

• Hemodynamic correction is critical for accurate biological interpretation in mesoscale calcium imaging.
• Vascular signals systematically bias estimates of functional organization, network architecture, and disease phenotypes.
• The study underscores that hemodynamic correction is more than a preprocessing step; it's a determinant of biological insight.