A Non-canonical Excitatory PV RGC-PV SC Visual Pathway for Mediating the Looming-evoked Innate Defensive Response.

Area of Science:

• Neuroscience
• Visual System
• Cell Biology

Background:

• Parvalbumin-positive retinal ganglion cells (PV+ RGCs) are vital for visual processing.
• Their specific role in visual information transmission and behavioral output is not well understood.

Purpose of the Study:

• To characterize PV+ RGCs in the retina.
• To investigate the downstream targets and functional role of the PV+ RGC-mediated visual pathway.

Main Methods:

• Multiple viral tracing strategies were employed to map PV+ RGC projections.
• Transcriptome expression profiling and immunofluorescence colocalization were used.
• Functional assays assessed the impact of PV+ RGC manipulation on behavior.

Main Results:

• PV+ RGCs project directly to PV+ excitatory neurons in the superior colliculus (SC).
• Ablation of SC-projecting PV+ RGCs impaired flight responses to looming stimuli but not visual acuity.
• PV+ RGCs were identified as predominantly glutamatergic neurons.

Conclusions:

• PV+ RGCs play a critical role in innate defensive responses, specifically the flight reaction to looming visual stimuli.
• A non-canonical subcortical visual pathway involving excitatory PV+ RGCs and PV+ SC neurons regulates this defensive behavior.
• This circuit represents a potential therapeutic target for neurological disorders like schizophrenia and autism.