Spatial extent of CBF response during whisker stimulation using trial averaged laser Doppler imaging.

Area of Science:

• Neuroscience
• Cerebrovascular Physiology

Background:

• The somatosensory cortex processes sensory input, including whisker information in rodents.
• Understanding the spatial dynamics of cerebral blood flow (CBF) responses to sensory stimulation is crucial for mapping neural activity.

Purpose of the Study:

• To investigate the spatial patterns of cerebral blood flow (CBF) changes in the rat somatosensory cortex during multiple whisker stimulation.
• To characterize the reproducibility and trial-dependent nature of these CBF responses using high-resolution laser Doppler imaging.

Main Methods:

• Utilized high-resolution laser Doppler (LD) imaging in urethane-anesthetized rats to measure CBF changes.
• Analyzed LD flux changes from single trials and averaged trials following multiple whisker stimulation.
• Quantified spatial overlap and reproducibility of activation patterns across trials.

Main Results:

• Single-trial CBF activation predominantly occurred over microvessels, forming reproducible diffuse circular patterns (400-800 microm) in layer IV of the somatosensory cortex.
• Activation patterns showed low trial-to-trial overlap (9-10%) but were consistent within and across rats.
• Trial averaging increased the number of activated pixels within diffuse circular regions, suggesting distinct responses in septal and barrel areas, with lower signal-to-noise ratio in barrel cores.

Conclusions:

• Diffuse circular activation patterns represent a reproducible neurovascular response to whisker stimulation at the barrel level.
• Trial averaging enhances the detection of subtle CBF changes within specific cortical regions, differentiating barrel and septal responses.
• Laser Doppler imaging provides high-resolution insights into the spatiotemporal dynamics of sensory-evoked CBF in the rodent brain.