Neural correlates for roughness choice in monkey second somatosensory cortex (SII)

Area of Science:

• Neuroscience
• Sensory Perception
• Computational Neuroscience

Background:

• Tactile perception of roughness is crucial for object interaction.
• The second somatosensory cortex (SII) is implicated in processing tactile information.
• Understanding the neural basis of tactile decision-making is essential.

Purpose of the Study:

• To investigate the relationship between neural activity in SII and roughness discrimination.
• To determine the influence of tactile variables (groove width, force, speed) on neural firing and behavior.
• To explore how neural firing patterns correlate with classification errors.

Main Methods:

• Monkeys classified tactile grating roughness based on groove width.
• Computer-controlled device delivered gratings with varying groove width, contact force, and scanning speed.
• Recorded neural firing patterns from 32 SII cells and analyzed behavioral performance.

Main Results:

• Contact force significantly disrupted roughness classification more than scanning speed.
• SII cell firing rates correlated with changes in groove width and force.
• Classification errors occurred when SII cell firing rates failed to distinguish gratings, particularly at specific force-groove width combinations.

Conclusions:

• Neural firing rates in SII appear to guide monkeys' tactile roughness classifications.
• Findings support existing human psychophysical data and extend tactile roughness models.
• The study provides evidence for SII's role in tactile decision-making based on neural coding of surface properties.