Superior colliculus control of vibrissa movements

Area of Science:

• Neuroscience
• Motor Control
• Sensory-Motor Integration

Background:

• The superior colliculus is implicated in sensorimotor functions.
• Whisking, a key sensory behavior in rodents, involves complex motor control.

Purpose of the Study:

• To investigate the superior colliculus's role in generating mystacial vibrissae movements (whisking).
• To compare whisking kinematics evoked by the superior colliculus versus the motor cortex.
• To determine if the superior colliculus functions as a simple sensory-driven reflex loop.

Main Methods:

• Comparing whisking kinematics evoked by microstimulation of the superior colliculus and motor cortex in anesthetized rats.
• Analyzing neuronal responses and field potentials of tecto-facial neurons to sensory vibrissa stimulation.

Main Results:

• Superior colliculus stimulation evoked sustained vibrissa protraction; motor cortex stimulation produced rhythmic protractions.
• Superior colliculus-generated movements were independent of the motor cortex, occurring at lower thresholds and shorter latencies.
• Most tecto-facial neurons did not receive sensory input, and sensory inputs did not spatially overlap with these neurons.

Conclusions:

• The superior colliculus plays a pivotal role in regulating vibrissa movement set point and whisking amplitude.
• The superior colliculus does not operate as a simple reflex loop for whisking.
• Superior colliculus control of set point and amplitude, combined with motor cortex control of frequency, accounts for voluntary whisking parameters.