Fast cortical dynamics encode tactile grating orientation during active touch

Area of Science:

• Neuroscience
• Sensory Perception
• Computational Neuroscience

Background:

• Touch-based object recognition involves perceiving tactile features like roughness and orientation.
• Neural encoding of tactile features, beyond roughness, remains poorly understood.
• The barrel cortex is crucial for processing whisker-dependent tactile information.

Purpose of the Study:

• To investigate how neural activity in the barrel cortex encodes tactile orientation.
• To differentiate between slow and fast neural dynamics in tactile perception.
• To link neural coding to behavioral decisions in a tactile discrimination task.

Main Methods:

• Developed a cortex-dependent perceptual task for mice to discriminate tactile grating orientation using whiskers.
• Performed multielectrode recordings in the barrel cortex during tactile exploration.
• Analyzed neural activity at different time scales (500 ms and 100 ms) and correlated it with psychophysical data.

Main Results:

• Average firing rates in the barrel cortex showed weak orientation tuning during grating exploration.
• Fast cortical dynamics (100-ms timescale) contained significant orientation information, closely matching psychophysical performance.
• This temporal code encoded both stimulus properties and choice-related information.

Conclusions:

• Fast neural dynamics, rather than average firing rates, are critical for encoding tactile orientation.
• A temporal code in the barrel cortex reflects physical stimuli and influences behavioral decisions.
• This highlights the importance of rapid neural fluctuations in tactile perception and action.