Bat eye movements resolve a long-standing question in gaze control.

Area of Science:

• Neuroscience
• Comparative Physiology
• Sensory Systems Biology

Background:

• Eye movements are crucial for visual information gathering and gaze stabilization via optokinetic (OKR) and vestibulo-ocular reflex (VOR) pathways.
• Bats were previously assumed to lack eye movements, a notion unsupported by empirical data.

Purpose of the Study:

• To quantitatively analyze eye movements in Seba's short-tailed bat (Carollia perspicillata) in response to visual and vestibular stimuli.
• To investigate the functional role of OKR and VOR pathways in bat gaze stabilization.

Main Methods:

• Quantitative analysis of eye movements in response to visual and vestibular stimulation.
• Micro-CT scans for semicircular canal geometry comparison between bats and mice.

Main Results:

• Bats exhibit robust, visually driven OKR (∼±10° oculomotor range) and strong otolith-mediated responses.
• Minimal semicircular canal-driven angular VOR (aVOR) was observed during passive head rotations.
• Semicircular canal anatomy in bats is similar to mice, ruling out peripheral constraints for weak aVOR.

Conclusions:

• Bats demonstrate significant eye movements and effective gaze stabilization through visual and otolith pathways.
• The limited aVOR suggests specialized vestibular processing in bats, potentially for active flight and behavioral states.