Functional imaging of perceptual learning in human primary and secondary somatosensory cortex.
Cellular mechanisms underlying synaptic plasticity are in line with the Hebbian concept. In contrast, data linking Hebbian learning to altered perception are rare. Combining functional magnetic resonance imaging with psychophysical tests, we studied cortical reorganization in primary and secondary somatosensory cortex (SI and SII) and the resulting changes of tactile perception before and after tactile coactivation, a simple type of Hebbian learning. Coactivation on the right index finger (IF) for 3 hr lowered its spatial discrimination threshold. In parallel, blood-oxygen level-dependent (BOLD) signals from the right IF representation in SI and SII enlarged. The individual threshold reduction was linearly correlated with the enlargement in SI, implying a close relation between altered discrimination and cortical reorganization. Controls consisting of a single-site stimulation did not affect thresholds and cortical maps. Accordingly, changes within distributed cortical networks based on Hebbian mechanisms alter the individual percept.
Pleger
Burkhard
B
Department of Neurology, Ruhr-University Bochum, BG-Kliniken Bergmannsheil, D-44789 Bochum, Germany.
Foerster
Ann Freya
AF
Ragert
Patrick
P
Dinse
Hubert R
HR
Schwenkreis
Peter
P
Malin
Jean Pierre
JP
Nicolas
Volkmar
V
Tegenthoff
Martin
M
D000328:Adult; D001931:Brain Mapping; D002755:Choice Behavior; D004056:Differential Threshold / Q000502:physiology; D005260:Female; D005385:Fingers / Q000098:blood supply / Q000294:innervation / Q000502:physiology; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007858:Learning / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010465:Perception / Q000502:physiology*; D010812:Physical Stimulation; D011603:Psychophysiology; D017603:Signal Detection, Psychological; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000502:physiology*; D013223:Statistics as Topic
D010100:Oxygen