Mapping function in the tree shrew visual system using functional ultrasound imaging.

Area of Science:

• Neuroscience
• Systems Neuroscience
• Vision Science

Background:

• The northern tree shrew is an emerging model organism for vision research, offering a unique bridge between rodent and primate systems.
• Understanding visual processing in tree shrews requires advanced functional neuroimaging techniques capable of high spatial and temporal resolution.

Purpose of the Study:

• To adapt and validate functional ultrasound imaging (fUSI) for functional brain mapping in awake, head-fixed northern tree shrews.
• To generate high-resolution functional maps of the visual cortex and associated subcortical structures in tree shrews.

Main Methods:

• Adapted functional ultrasound imaging (fUSI) for awake, head-fixed northern tree shrews.
• Utilized retinotopic stimuli, full-field noise, motion localizers, and object-based contrasts to elicit visual responses.
• Achieved approximately 100 μm spatial and 100 ms temporal resolution for hemodynamic mapping.

Main Results:

• Demonstrated robust, spatially specific hemodynamic responses across visual processing areas, including cortex, superior colliculus, and subcortical structures.
• Successfully mapped retinotopic organization, laterality, and stimulus-selective modules within the visual system.
• Obtained high signal-to-noise ratio percentage changes in cerebral blood volume (%CBV), enabling efficient single-session functional mapping.

Conclusions:

• Established fUSI as a powerful and scalable tool for functional brain mapping in the northern tree shrew.
• fUSI provides mesoscale functional maps that complement high-density electrophysiology, aiding systems-level understanding of visual circuits.
• Accelerates the utility of the tree shrew model for vision research, bridging genetic insights from rodents and primate visual systems.