Structure, function, and cortical representation of the rat submandibular whisker trident

Area of Science:

• Neurobiology
• Sensory systems
• Somatosensory cortex

Background:

• Rodent facial whiskers are well-studied, but other vibrissae, like the chin whisker trident, remain under-investigated.
• The rat's whisker trident is a three-whisker array with a distinct midline whisker.

Purpose of the Study:

• To investigate the function and neurobiology of the rat's under-utilized whisker trident.
• To explore the sensory capabilities of the trident vibrissae during locomotion and ground contact.

Main Methods:

• Biomechanical analysis of trident whisker movement during simulated ground contact.
• Identification and characterization of whisker barrels in the somatosensory cortex.
• Electrophysiological recordings of cortical responses to whisker stimulation.

Main Results:

• Trident whiskers exhibit smooth ground tracking and reduced deflection angles with increased ground velocity.
• A significantly larger and elongated whisker barrel for the midline trident whisker was identified in the somatosensory cortex.
• Trident whisker cortical responses show lower temporal precision compared to facial whiskers, suggesting a non-object-detection role.

Conclusions:

• The whisker trident's unique biomechanics and neural representation suggest a primary role in idiothetic sensing (self-motion detection) and heading direction.
• Trident whiskers may function as a tactile speedometer, providing continuous ego-motion information from ground interactions.
• The midline position of the trident enhances its utility for sensing directional information.