Pathway-specific inputs to the superior colliculus support flexible responses to visual threat

Area of Science:

• Neuroscience
• Sensory processing
• Behavioral circuits

Background:

• Behavioral flexibility depends on precise sensory information routing.
• The superior colliculus (SC) uses divergent outputs for visual threat responses, but its circuit organization for flexible routing is unclear.
• Inhibitory Gad2 neurons in the SC are key to this process.

Purpose of the Study:

• To elucidate the circuit organization enabling flexible routing of sensory information in the superior colliculus.
• To investigate the role of Gad2 neurons projecting to the LGN and PBG in visual threat responses.

Main Methods:

• Trans-synaptic tracing to identify neuronal connectivity.
• Neuronal recordings to assess neural activity.
• Inhibitory and optogenetic manipulation of Gad2 neuron populations.

Main Results:

• Gad2 neurons projecting to the LGN and PBG constitute separate populations with distinct non-retinal inputs.
• Inhibiting LGN-projecting Gad2 neurons increased freezing, while inhibiting PBG-projecting neurons increased escape probability to visual looming.
• Optogenetic activation of specific inputs to these Gad2 populations predictably modulated threat responses.

Conclusions:

• Projection-specific sampling of brain-wide inputs is a circuit design principle in the SC.
• This mechanism enables selective routing of visual information to produce context-specific behaviors.
• Gad2 neurons play a critical role in mediating behavioral flexibility to visual threats.