title: Altered Onset Response Dynamics in Somatosensory Processing in Autism Spectrum Disorder.
abstract: Abnormalities in cortical connectivity and evoked responses have been extensively documented in autism spectrum disorder (ASD). However, specific signatures of these cortical abnormalities remain elusive, with data pointing toward abnormal patterns of both increased and reduced response amplitudes and functional connectivity. We have previously proposed, using magnetoencephalography (MEG) data, that apparent inconsistencies in prior studies could be reconciled if functional connectivity in ASD was reduced in the feedback (top-down) direction, but increased in the feedforward (bottom-up) direction. Here, we continue this line of investigation by assessing abnormalities restricted to the onset, feedforward inputs driven, component of the response to vibrotactile stimuli in somatosensory cortex in ASD. Using a novel method that measures the spatio-temporal divergence of cortical activation, we found that relative to typically developing participants, the ASD group was characterized by an increase in the initial onset component of the cortical response, and a faster spread of local activity. Given the early time window, the results could be interpreted as increased thalamocortical feedforward connectivity in ASD, and offer a plausible mechanism for the previously observed increased response variability in ASD, as well as for the commonly observed behaviorally measured tactile processing abnormalities associated with the disorder.
authors.affiliation: Department of Neurology, Massachusetts General HospitalBoston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA; Harvard Medical SchoolBoston, MA, USA; McGovern Institute for Brain Research, Massachusetts Institute of TechnologyCambridge, MA, USA.
authors.forename: Sheraz
authors.initials: S
authors.lastname: Khan
authors.affiliation: Department of Neurology, Massachusetts General HospitalBoston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA; Harvard Medical SchoolBoston, MA, USA.
authors.forename: Javeria A
authors.initials: JA
authors.lastname: Hashmi
authors.affiliation: Department of Neurology, Massachusetts General HospitalBoston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA; Harvard Medical SchoolBoston, MA, USA.
authors.forename: Fahimeh
authors.initials: F
authors.lastname: Mamashli
authors.affiliation: Department of Neurology, Massachusetts General HospitalBoston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA; Harvard Medical SchoolBoston, MA, USA.
authors.forename: Hari M
authors.initials: HM
authors.lastname: Bharadwaj
authors.affiliation: Department of Neurology, Massachusetts General HospitalBoston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA.
authors.forename: Santosh
authors.initials: S
authors.lastname: Ganesan
authors.affiliation: Department of Computer Science, Rutgers University Piscataway, NJ, USA.
authors.forename: Konstantinos P
authors.initials: KP
authors.lastname: Michmizos
authors.affiliation: Department of Neurology, Massachusetts General HospitalBoston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA; Harvard Medical SchoolBoston, MA, USA.
authors.forename: Manfred G
authors.initials: MG
authors.lastname: Kitzbichler
authors.affiliation: Department of Neurology, Massachusetts General HospitalBoston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA.
authors.forename: Manuel
authors.initials: M
authors.lastname: Zetino
authors.affiliation: Department of Neurology, Massachusetts General HospitalBoston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA.
authors.forename: Keri-Lee A
authors.initials: KL
authors.lastname: Garel
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA; Harvard Medical SchoolBoston, MA, USA; Department of Radiology, Massachusetts General HospitalBoston, MA, USA; Department of Neuroscience and Biomedical Engineering, Aalto University School of ScienceEspoo, Finland.
authors.forename: Matti S
authors.initials: MS
authors.lastname: Hämäläinen
authors.affiliation: Department of Neurology, Massachusetts General HospitalBoston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, MGH/MIT/HarvardBoston, MA, USA; Harvard Medical SchoolBoston, MA, USA.
authors.forename: Tal
authors.initials: T
authors.lastname: Kenet
keywords: autism spectrum disorders (ASD); biomarker; cortical connectivity; feedback; feedforward; magnetoencephalography (MEG); somatosensory cortex; tactile sensing