title: BOLD adaptation in vibrotactile stimulation: neuronal networks involved in frequency discrimination.
abstract: The present functional magnetic resonance imaging (fMRI) study investigated human brain regions subserving the discrimination of vibrotactile frequency. An event-related adaptation paradigm was used in which blood-oxygen-level-dependent (BOLD) responses are lower to same compared with different pairs of stimuli (BOLD adaptation). This adaptation effect serves as an indicator for feature-specific responding of neuronal subpopulations. Subjects had to discriminate two vibrotactile stimuli sequentially applied with a delay of 600 ms to their left middle fingertip. The stimulus frequency was in the flutter range of 18-26 Hz. In half of the trials, the two stimuli possessed identical frequency (same), whereas in the other half, a frequency difference of +/-2 Hz was used (diff). As a result, BOLD adaptation was observed in the contralateral primary somatosensory cortex (S1), precentral gyrus, superior temporal gyrus (STG); ipsilateral insula as well as bilateral secondary somatosensory cortex and supplementary motor area. When statistically comparing the BOLD time courses between same and diff trials in these cortical areas, it was found that the vibrotactile BOLD adaptation is initiated in the contralateral S1 and STG simultaneously. These findings suggest that the cortical areas responsive to the frequency difference between two serially presented stimuli sequentially process the frequency of a vibrotactile stimulus and constitute a putative neuronal network underlying human vibrotactile frequency discrimination.
authors.affiliation: Institute of MedicalPsychology and Behavioral Neurobiolopgy, and MEG-Center, International Max Planck Research School, Otfried-Müller-Strasse 47, 72076 Tübingen, Germany. yiwen.li@med.uni-tuebingen.de
authors.forename: Yiwen
authors.initials: Y
authors.lastname: Li  Hegner
authors.forename: Ralf
authors.initials: R
authors.lastname: Saur
authors.forename: Ralf
authors.initials: R
authors.lastname: Veit
authors.forename: Raymond
authors.initials: R
authors.lastname: Butts
authors.forename: Susanne
authors.initials: S
authors.lastname: Leiberg
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Grodd
authors.forename: Christoph
authors.initials: C
authors.lastname: Braun
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005071:Evoked Potentials / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D009415:Nerve Net / Q000033:anatomy & histology / Q000502:physiology*; D009434:Neural Pathways / Q000033:anatomy & histology / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D010812:Physical Stimulation; D014110:Touch / Q000502:physiology*; D014732:Vibration