Phase-to-rate transformations encode touch in cortical neurons of a scanning sensorimotor system

Area of Science:

• Neuroscience
• Sensory Perception
• Motor Control

Background:

• Sensory perception requires integrating external stimuli with self-generated motion.
• Body position changes can significantly alter the sensory field, posing a challenge for accurate perception.
• Understanding how the brain combines sensory input with motor commands is crucial for explaining adaptive behaviors.

Purpose of the Study:

• To investigate neural mechanisms in the primary somatosensory cortex that integrate sensory signals from external stimuli and motor activity.
• To determine how rats use vibrissal (whiskers) information to locate objects during active exploration.
• To elucidate the computational principles underlying sensory-motor integration in tactile perception.

Main Methods:

• Electrophysiological recordings from neurons in the primary somatosensory cortex of rats.
• Training rats to perform a rhythmic vibrissa sweeping task to find a target.
• Analyzing neuronal responses in relation to tactile stimuli and the phase of the whisking cycle.

Main Results:

• A subset of neurons in the primary somatosensory cortex exhibited transient excitation.
• This excitation occurred at the convergence of vibrissal touch and specific phases of the whisking cycle.
• Neuronal responses were phase-dependent, indicating a neural code normalized to motor output trajectory.

Conclusions:

• Rodents can estimate object position in a coordinate frame normalized to their motor output (whisking phase).
• This neural computation allows for robust object localization irrespective of the vibrissa's angle relative to the face.
• The findings suggest a computational mechanism involving inhibitory gating for sensory-motor integration in tactile processing.