Whisker-related afferents in superior colliculus

Area of Science:

• Neuroscience
• Sensory processing
• Whisking behavior

Background:

• The superior colliculus (SC) is crucial for processing whisker-mediated sensory information in rodents.
• Its intermediate layers integrate inputs from the trigeminal complex (trigeminotectal) and barrel cortex (corticotectal).

Purpose of the Study:

• To investigate the synaptic organization and response properties of trigeminotectal and corticotectal afferents in the mouse SC.
• To understand how these inputs contribute to whisker sensory processing and adaptation.

Main Methods:

• Histological analysis of synaptic overlap in the mouse SC.
• In vivo electrophysiological recordings and optogenetics in anesthetized mice.
• In vitro slice electrophysiology and optogenetics in adult mice.

Main Results:

• Trigeminotectal and corticotectal synapses show partial overlap in the intermediate granular layer of the SC.
• Whisker deflections elicit successive trigeminotectal and corticotectal responses in the SC.
• Trigeminotectal inputs are more efficacious but depress more strongly with frequency than corticotectal inputs.

Conclusions:

• The SC's intermediate layers are tuned to process strong, infrequent trigeminal inputs and weak, persistent cortical inputs.
• This differential tuning explains rapid sensory adaptation observed in whisker responses within the SC.