The neural substrate for working memory of tactile surface texture.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Sensory Perception

Background:

• Fine surface texture discrimination relies heavily on touch, unlike macro geometric features.
• Understanding the neural basis of tactile working memory is essential for explaining sensory processing.

Purpose of the Study:

• To investigate the neural substrates supporting working memory for tactile surface texture using functional magnetic resonance imaging (fMRI).
• To differentiate brain activity related to encoding and maintaining tactile texture information versus spatial location.

Main Methods:

• Participants performed a delayed match-to-sample task involving encoding tactile textures or locations of sandpaper stimuli.
• fMRI was used to measure brain activity during encoding and delay phases, with varying task demands (texture vs. location) and memory load.
• Analyses of variance examined percent signal change in sensorimotor and prefrontal regions.

Main Results:

• Encoding tactile texture engaged contralateral sensorimotor regions, while memory load affected bilateral postcentral sulcus (BA2), secondary somatosensory cortex (S2), pre-SMA, dorsolateral prefrontal cortex (dlPFC), and superior parietal lobule (SPL).
• Both encoding and delay phases showed task effects (texture > location) in the central sulcus, S2, pre-SMA, dlPFC, and SPL.
• Specific regions (BA2, S2) showed hand- and modality-specific effects, while other regions (dlPFC, pre-SMA, SPL) demonstrated hand- and modality-unspecific cognitive control functions.

Conclusions:

• The secondary somatosensory cortex (S2) plays a critical role in encoding and maintaining tactile surface texture information.
• Parieto-frontal networks exhibit supramodal characteristics, contributing to cognitive control in tactile working memory.
• Findings highlight the distinct and overlapping neural mechanisms for processing tactile features and cognitive control.