Slip-Based Coding of Local Shape and Texture in Mouse S1.

Area of Science:

• Neuroscience
• Sensory Systems
• Somatosensation

Background:

• Active touch involves encoding both local geometry and macroscopic texture.
• The neural mechanisms for simultaneous encoding of spatial scales during touch remain unclear.
• The rodent whisker system provides a model for investigating tactile information processing.

Purpose of the Study:

• To investigate how whisker micromotions (stick-slips) and subsequent neural spikes encode tactile object properties.
• To determine if a shared neural code exists for local shape and broader texture.
• To explore the role of the somatosensory cortex (S1) in processing this tactile information.

Main Methods:

• Mice were trained to discriminate between smooth and rough surfaces using active touch.
• Whisker movements, specifically stick-slips, and neural activity in S1 were recorded.
• Analysis focused on the temporal precision of slip-evoked spikes and their correlation with surface features.

Main Results:

• Whisker slips precisely locked to surface ridges, evoking temporally precise spikes in S1 with <10 ms jitter.
• These slip-evoked spikes enabled accurate resolution of features approximately 1 mm apart.
• Both slip-evoked spikes and a non-slip signal contributed to a population firing rate code for roughness, allowing accurate texture discrimination.

Conclusions:

• Stick-slips generate spatially and temporally precise neural signals in S1.
• These signals simultaneously encode local shape (ridges) and contribute to a macroscopic firing rate code for texture.
• The whisker system demonstrates an integrated neural strategy for processing tactile information across multiple spatial scales.