Abstract
Our sense of touch confers to us the ability to perceive textural features over a broad range of spatial scales and material properties, giving rise to a complex sensory experience. To understand the neural basis of texture perception requires that somatosensory neurons be stimulated with textures that tile the space of spatial scales and material properties experienced during everyday interactions with objects. We have previously shown that neurons in early stages of somatosensory processing – the nerves and somatosensory cortex (S1) – are highly sensitive to texture and carry a representation of texture that is highly informative about the surface but also predicts the evoked sensory experience. In contrast, the texture signals in higher order areas – secondary somatosensory cortex (S2) and the parietal ventral area (PV) – have never been investigated with a rich and naturalistic textural set. To fill this gap, we recorded single-unit activity in S2/PV of macaques while they performed a texture discrimination task. We then characterized the neural responses to texture and compared these to their counterparts in somatosensory cortex (S1). We found that texture responses in S2/PV differ from their S1 counterparts in several ways. First, texture responses are far sparser in S2/PV than in S1: While individual S1 neurons respond promiscuously to most textures, S2/PV neurons tend to respond to only a few textures. Second, S2/PV responses co-vary only weakly with roughness, the dominant perceptual axis of texture. Third, S2/PV signals carry information about task variables – the animal’s perceptual decision. Fourth, the millisecond scale temporal patterning in the texture response observed in S1 has all but disappeared in S2/PV.
Competing Interest Statement
The authors have declared no competing interest.
