Active Dendritic Properties and Local Inhibitory Input Enable Selectivity for Object Motion in Mouse Superior...

Area of Science:

• Neuroscience
• Visual System Processing
• Cellular Electrophysiology

Background:

• Neurons exhibit feature-specific responses to sensory stimuli.
• Understanding the mechanisms of response selectivity in neural circuits is crucial for deciphering sensory processing.
• Wide-field (WF) cells in the superior colliculus (SC) are involved in visual motion detection.

Purpose of the Study:

• To investigate how wide-field (WF) cells in the mouse superior colliculus (SC) achieve selectivity for small moving objects.
• To identify the cellular and circuit mechanisms underlying this selective response.
• To elucidate the role of dendritic spikes and inhibitory inputs in shaping WF cell responses.

Main Methods:

• In vivo whole-cell recordings from WF cells in the mouse SC.
• Optogenetic manipulation of inhibitory horizontal cell activity.
• Analysis of action potential initiation sites and propagation.
• Stimulus-evoked response characterization to varying object sizes and motion patterns.

Main Results:

• WF cells in the SC demonstrate selective responses to small moving objects, not large ones or full-field motion.
• Dendritic spikes, initiated in the dendrites of WF cells, reliably propagate to the soma and drive action potentials.
• Inhibitory input from SC horizontal cells, which prefer large or rapidly moving stimuli, plays a critical role in refining WF cell selectivity.
• Reducing horizontal cell activity broadens WF cell tuning and diminishes movement selectivity.

Conclusions:

• Strongly propagating dendritic spikes are essential for enabling small stimuli to drive WF cell output.
• Local inhibition, mediated by horizontal cells, restricts WF cell responses to stimuli that are both small and moving.
• These mechanisms collectively contribute to the emergence of response selectivity in the visual SC.