title: Layer-specific interhemispheric functional connectivity in the somatosensory cortex of rats: resting state electrophysiology and fMRI studies.
abstract: The spontaneous cerebral hemodynamic fluctuations observed during the resting state have been frequently visualized using functional magnetic resonance imaging (rsfMRI). However, the neuronal populations and neuroelectric characteristics underlying the functional connectivity of cerebrohemodynamic activities are poorly understood. We investigated the characteristics of bi-hemispheric functional connectivity via electrophysiology and rsfMRI in the primary sensory cortex of rats anesthetized by α-chloralose. Unlike the evoked responses, the spontaneous electrophysiological activity was concentrated in the infragranular layers and could be classified into subtypes with distinctive current sources and sinks. Both neuroelectric and rsfMRI signals were interhemispherically correlated in a layer-specific manner, suggesting that there are independent neural inputs to infragranular and granular/supragranular layers. The majority of spontaneous electrophysiological activities were bilaterally paired with delays of up to ~50 ms between each pair. The variable interhemispheric delay implies the involvement of indirect, multi-neural pathways. Our findings demonstrated the diverse activity patterns of layer-specific electrophysiological substrates and suggest the recruitment of multiple, non-specific brain regions in construction of interhemispheric functional connectivity.
authors.affiliation: Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701, South Korea.|Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 13th St., Charlestown, MA, 02129, USA.
authors.forename: Kwangyeol
authors.initials: K
authors.lastname: Baek
authors.affiliation: Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701, South Korea.|Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 13th St., Charlestown, MA, 02129, USA.
authors.forename: Woo Hyun
authors.initials: WH
authors.lastname: Shim
authors.affiliation: Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 305-701, South Korea. jsjeong@kaist.ac.kr.
authors.forename: Jaeseung
authors.initials: J
authors.lastname: Jeong
authors.affiliation: Center for Neural Engineering, Pennsylvania State University, University Park, PA, USA.
authors.forename: Harsha
authors.initials: H
authors.lastname: Radhakrishnan
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 13th St., Charlestown, MA, 02129, USA.|Harvard Medical School, Boston, MA, USA.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Rosen
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 13th St., Charlestown, MA, 02129, USA.|Harvard Medical School, Boston, MA, USA.
authors.forename: David
authors.initials: D
authors.lastname: Boas
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 13th St., Charlestown, MA, 02129, USA.|Harvard Medical School, Boston, MA, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Franceschini
authors.affiliation: Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA.
authors.forename: Bharat B
authors.initials: BB
authors.lastname: Biswal
authors.affiliation: Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 13th St., Charlestown, MA, 02129, USA. spmn@nmr.mgh.harvard.edu.|Harvard Medical School, Boston, MA, USA. spmn@nmr.mgh.harvard.edu.|Ulsan National Institute of Science and Technology, Ulsan, South Korea. spmn@nmr.mgh.harvard.edu.
authors.forename: Young R
authors.initials: YR
authors.lastname: Kim
mesh_terms: D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D000818:Animals; D001931:Brain Mapping; D002698:Chloralose / Q000008:administration & dosage; D005552:Forelimb / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D010812:Physical Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000187:drug effects / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*
chemical_list: D018686:Anesthetics, Intravenous; D002698:Chloralose
keywords: Cortical layers; Interhemispheric connectivity; Local field potential; Resting state fMRI; Spontaneous activity