Fig. 3: Layer-specific somatosensory maps.

a Location of neural recordings across cortical layers (left). Cortical surface maps determined using graphene electrodes were compared to cortical layer 1/2, and four maps were produced using penetrating electrodes (middle). Color-coded somatosensory maps were constructed using the response amplitudes and overlapped with the homunculus (right). b Cortical responses and maps were recorded following the stimulation of each body part. Notably, the response amplitude and area stimulated by various somatosensory stimuli gradually decreased and expanded from layer 4 to layer 1/2 and to the cortical surface, respectively. c Response amplitude and area across cortical layers were quantified by the size and location of LFPs. The area was normalized to the area recorded using graphene electrodes because of the different geographical locations of each somatosensory part. The response amplitude and area gradually decreased and expanded, respectively, as the electrodes were moved from cortical layer 4 to superficial layer 1/2 and to the cortical surface. Cortical-surface recordings obtained using graphene arrays show weaker responses and less stimulus selectivity than those obtained with penetrating electrodes. Data are presented as the mean ± standard error (SEM). **p < 0.01; ^n.s.p > 0.05.