Visually-Driven Maps in Area 3b

• Published in: The Journal of neuroscience 2018-01, Vol.38 (5), p.1295-1310
• Main Authors: Kuehn, Esther, Haggard, Patrick, Villringer, Arno, Pleger, Burkhard, Sereno, Martin I
• Format: Article
• Language: English
• Subjects: Adult; Brain; Brain mapping; Brain Mapping - methods; Cortex (somatosensory); Counterflow; Electromyography; Female; Fingers; Fingers - innervation; Fingers - physiology; Functional magnetic resonance imaging; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Mechanical stimuli; Medical imaging; Muscle, Skeletal - innervation; Muscle, Skeletal - physiology; Neuroimaging; Neurology; Observation; Photic Stimulation; Physical Stimulation; Sensory perception; Somatosensory Cortex - diagnostic imaging; Somatosensory Cortex - physiology; Tactile; Topographic mapping; Touch - physiology; Young Adult
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/jneurosci.0491-17.2017

Sensory perception relies on the precise neuronal encoding of modality-specific environmental features in primary sensory cortices. Some studies have reported the penetration of signals from other modalities even into early sensory areas. So far, no comprehensive account of maps induced by "foreign sources" exists. We addressed this question using surface-based topographic mapping techniques applied to ultra-high resolution fMRI neuroimaging data, measured in female participants. We show that fine-grained finger maps in human primary somatosensory cortex, area 3b, are somatotopically activated not only during tactile mechanical stimulation, but also when viewing the same fingers being touched. Visually-induced maps were weak in amplitude, but overlapped with the stronger tactile maps tangential to the cortical sheet when finger touches were observed in both first- and third-person perspectives. However, visually-induced maps did not overlap tactile maps when the observed fingers were only approached by an object but not actually touched. Our data provide evidence that "foreign source maps" in early sensory cortices are present in the healthy human brain, that their arrangement is precise, and that their induction is feature-selective. The computations required to generate such specific responses suggest that counterflow (feedback) processing may be much more spatially specific than has been often assumed. Using ultra-high field fMRI, we provide empirical evidence that viewing touches activates topographically aligned single finger maps in human primary somatosensory cortical area 3b. This shows that "foreign source maps" in early sensory cortices are topographic, precise, and feature-selective in healthy human participants with intact sensory pathways.