DC-magnetoencephalography and time-resolved near-infrared spectroscopy combined to study neuronal and vascular brain responses

Physiol Meas. 2007 Jun;28(6):651-64. doi: 10.1088/0967-3334/28/6/004. Epub 2007 May 3.

Abstract

The temporal relation between vascular and neuronal responses of the brain to external stimuli is not precisely known. For a better understanding of the neuro-vascular coupling changes in cerebral blood volume and oxygenation have to be measured simultaneously with neuronal currents. With this motivation modulation dc-magnetoencephalography was combined with multi-channel time-resolved near-infrared spectroscopy to simultaneously monitor neuronal and vascular parameters on a scale of seconds. Here, the technique is described, how magnetic and optical signals can be measured simultaneously. In a simple motor activation paradigm (alternating 30 s of finger movement with 30 s of rest for 40 min) both signals were recorded non-invasively over the motor cortex of eight subjects. The off-line averaged signals from both modalities showed distinct stimulation related changes. By plotting changes in oxy- or deoxyhaemoglobin as a function of magnetic field a characteristic trajectory was created, which was similar to a hysteresis loop. A parametric analysis allowed quantitative results regarding the timing of coupling: the vascular signal increased significantly slower than the neuronal signal.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brain / blood supply*
  • Brain / physiology*
  • Humans
  • Magnetoencephalography / methods*
  • Neurons / physiology*
  • Spectroscopy, Near-Infrared / methods*
  • Time Factors