title: An Internet-Based Real-Time Audiovisual Link for Dual MEG Recordings.
abstract: Most neuroimaging studies of human social cognition have focused on brain activity of single subjects. More recently, "two-person neuroimaging" has been introduced, with simultaneous recordings of brain signals from two subjects involved in social interaction. These simultaneous "hyperscanning" recordings have already been carried out with a spectrum of neuroimaging modalities, such as functional magnetic resonance imaging (fMRI), electroencephalography (EEG), and functional near-infrared spectroscopy (fNIRS).
  We have recently developed a setup for simultaneous magnetoencephalographic (MEG) recordings of two subjects that communicate in real time over an audio link between two geographically separated MEG laboratories. Here we present an extended version of the setup, where we have added a video connection and replaced the telephone-landline-based link with an Internet connection. Our setup enabled transmission of video and audio streams between the sites with a one-way communication latency of about 130 ms. Our software that allows reproducing the setup is publicly available.
  
  
  RESULTS
  We demonstrate that the audiovisual Internet-based link can mediate real-time interaction between two subjects who try to mirror each others' hand movements that they can see via the video link. All the nine pairs were able to synchronize their behavior. In addition to the video, we captured the subjects' movements with accelerometers attached to their index fingers; we determined from these signals that the average synchronization accuracy was 215 ms. In one subject pair we demonstrate inter-subject coherence patterns of the MEG signals that peak over the sensorimotor areas contralateral to the hand used in the task.
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland; MEG Core, Aalto Neuroimaging, Aalto University, Espoo, Finland; BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Andrey
authors.initials: A
authors.lastname: Zhdanov
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Nurminen
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Pamela
authors.initials: P
authors.lastname: Baess
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Lotta
authors.initials: L
authors.lastname: Hirvenkari
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Veikko
authors.initials: V
authors.lastname: Jousmäki
authors.affiliation: BioMag Laboratory, HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
authors.forename: Jyrki P
authors.initials: JP
authors.lastname: Mäkelä
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Anne
authors.initials: A
authors.lastname: Mandel
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Lassi
authors.initials: L
authors.lastname: Meronen
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Riitta
authors.initials: R
authors.lastname: Hari
authors.affiliation: Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Lauri
authors.initials: L
authors.lastname: Parkkonen
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology; D001931:Brain Mapping / Q000379:methods*; D058256:Brain Waves / Q000502:physiology*; D003142:Communication; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006801:Humans; D020407:Internet; D007398:Interpersonal Relations; D008279:Magnetic Resonance Imaging / Q000379:methods; D015225:Magnetoencephalography / Q000295:instrumentation / Q000379:methods*; D008297:Male; D059906:Neuroimaging / Q000379:methods*; D019265:Spectroscopy, Near-Infrared / Q000379:methods; D014741:Video Recording; D055815:Young Adult