BCIwiki (bciwiki.com) — A collaboration involving the California Institute of Technology, US, posted a preprint to bioRxiv on October 11, 2026. It compared links between cortical activity and touch perception using human single-neuron recordings. Primary somatosensory cortex (S1) responses closely tracked physical stimulus amplitude, whereas posterior parietal cortex (PPC) activity covaried more strongly with awareness and confidence. The preprint has not been peer reviewed.
The study involved three participants with tetraplegia. Natural vibrotactile stimuli were delivered to a sensate upper-limb region while chronic intracortical recordings simultaneously monitored large ensembles of single neurons in grasp-related cortical areas. During near-threshold trials, identical stimuli were sometimes felt and sometimes missed, allowing comparison of subjective perception under similar physical input. Coordinated neural activity emerged across the distributed grasp-related parietal-frontal network.
The researchers then focused on PPC and S1, comparing their associations with stimulus amplitude, awareness, and confidence. The authors interpreted the findings as complementary neural codes, proposing that PPC transforms physical stimulation into conscious perception while S1 is more sensitive to stimulus amplitude. That functional interpretation is distinct from the observations: the recordings show correlations between neural activity and perceptual measures, which alone do not establish causality.
The full text reports that participants indicated whether they felt the stimulus after each trial. Two participants additionally rated their confidence from 1 to 10; confidence analysis of non-felt trials used data from only one participant. The participant sample therefore differed across analyses.