Scientific RepoRts | 7: 172 | DOI:10.1038/s41598-017-00293-7
Multimodal brain imaging with
method for measuring blood
pressure and cardiorespiratory
, Norman Zacharias
, Vesa Korhonen
, Aleksandra Zienkiewicz
, Vesa Kiviniemi
& Martin Walter
Studies with magnetoencephalography (MEG) are still quite rarely combined simultaneously with
methods that can provide a metabolic dimension to MEG investigations. In addition, continuous
blood pressure measurements which comply with MEG compatibility requirements are lacking. For
instance, by combining methods reecting neurovascular status one could obtain more information
on low frequency uctuations that have recently gained increasing interest as a mediator of functional
connectivity within brain networks. This paper presents a multimodal brain imaging setup, capable to
non-invasively and continuously measure cerebral hemodynamic, cardiorespiratory and blood pressure
oscillations simultaneously with MEG. In the setup, all methods apart from MEG rely on the use of
bre optics. In particular, we present a method for measuring of blood pressure and cardiorespiratory
oscillations continuously with MEG. The potential of this type of multimodal setup for brain research
is demonstrated by our preliminary studies on human, showing eects of mild hypercapnia, gathered
simultaneously with the presented modalities.
Combining dierent brain imaging techniques enables us to study the causality between complex neurological
mechanisms and variables. For instance, an increase in neuronal activity causes a metabolic demand for glucose
and oxygen, which increases cerebral blood ow to the active brain region. is kind of process is impossible to
study accurately by any single imaging modality, but requires simultaneous use of hemodynamic and electro-
magnetic based imaging techniques. In consequence, multimodal imaging, such as electroencephalogram (EEG)
with magnetoencephalography (MEG) or functional magnetic resonance imaging (fMRI) is a common practice
in modern day neuroimaging. In addition, such imaging techniques would draw an advantage if cardiovascular
and cerebral hemodynamic related signals are recorded comprehensive and in synchrony. is would extend our
possibilities to acquire detailed knowledge of the functional interconnections between the brain and other organs
and, for example, to study autoregulation of blood pressure (BP).
MEG, closely related to EEG, measures the magnetic elds created by the electric currents, whereas EEG
measures electric potentials by electrodes placed at certain points on the scalp. e main dierence between
the sources of EEG and MEG signals is that MEG only picks signals from the dendrites tangential to the head
surface. Both of these methods can directly measure neuronal activity with a time resolution of less than one mil-
lisecond and with a high amount of channels, commonly MEG from 100 to 300
. In general, EEG has a relatively
modest spatial resolution, on the centimetre scale, whereas MEG has a higher spatial accuracy, few millimetres
University of Oulu, Optoelectronics and Measurement Techniques Research Unit, Health & Wellness Measurements
Group, Oulu, Finland.
Leibniz Institute for Neurobiology, Magdeburg, Germany.
Charité – Universitätsmedizin
Berlin, Department of Anesthesiology, Neuroimaging Research Group, Berlin, Germany.
Oulu University Hospital,
Department of Diagnostic Radiology, Oulu, Finland.
University of Oulu, Research Unit of Medical Imaging, Physics
and Technology, Oulu Functional NeuroImaging Group, Oulu, Finland.
University Hospital Magdeburg, Clinic
for Neurology, Magdeburg, Germany.
University of Tübingen, Department of Psychiatry, Tübingen, Germany.
Correspondence and requests for materials should be addressed to T.M. (email: teemu.myllyla@oulu.)
Received: 6 June 2016
Accepted: 17 February 2017
Published: xx xx xxxx