Biological Cybernetics

, Volume 103, Issue 6, pp 415–432

Applying double-magnetic induction to measure head-unrestrained gaze shifts: calibration and validation in monkey

  • Peter Bremen
  • Robert F. Van der Willigen
  • Marc M. Van Wanrooij
  • David F. Schaling
  • Marijn B. Martens
  • Tom J. Van Grootel
  • A. John van Opstal
Open Access
Original Paper

DOI: 10.1007/s00422-010-0408-4

Cite this article as:
Bremen, P., Van der Willigen, R.F., Van Wanrooij, M.M. et al. Biol Cybern (2010) 103: 415. doi:10.1007/s00422-010-0408-4

Abstract

The double magnetic induction (DMI) method has successfully been used to record head-unrestrained gaze shifts in human subjects (Bremen et al., J Neurosci Methods 160:75–84, 2007a, J Neurophysiol, 98:3759–3769, 2007b). This method employs a small golden ring placed on the eye that, when positioned within oscillating magnetic fields, induces orientation-dependent voltages in a pickup coil in front of the eye. Here we develop and test a streamlined calibration routine for use with experimental animals, in particular, with monkeys. The calibration routine requires the animal solely to accurately follow visual targets presented at random locations in the visual field. Animals can readily learn this task. In addition, we use the fact that the pickup coil can be fixed rigidly and reproducibly on implants on the animal’s skull. Therefore, accumulation of calibration data leads to increasing accuracy. As a first step, we simulated gaze shifts and the resulting DMI signals. Our simulations showed that the complex DMI signals can be effectively calibrated with the use of random target sequences, which elicit substantial decoupling of eye- and head orientations in a natural way. Subsequently, we tested our paradigm on three macaque monkeys. Our results show that the data for a successful calibration can be collected in a single recording session, in which the monkey makes about 1,500–2,000 goal-directed saccades. We obtained a resolution of 30 arc minutes (measurement range [−60,+60]°). This resolution compares to the fixation resolution of the monkey’s oculomotor system, and to the standard scleral search-coil method.

Keywords

DMI Search coil Simulation Eye movements Saccade Macaca mulatta 

Copyright information

© The Author(s) 2010

Authors and Affiliations

  • Peter Bremen
    • 1
    • 3
  • Robert F. Van der Willigen
    • 1
  • Marc M. Van Wanrooij
    • 1
  • David F. Schaling
    • 2
  • Marijn B. Martens
    • 1
  • Tom J. Van Grootel
    • 1
  • A. John van Opstal
    • 1
  1. 1.Donders Institute for Brain, Cognition and Behaviour, Department of BiophysicsRadboud University NijmegenNijmegenThe Netherlands
  2. 2.Department of OphthalmologyRadboud University Nijmegen Medical CenterNijmegenThe Netherlands
  3. 3.Laboratory of Auditory Neurophysiology, Department of NeurosciencesKU LeuvenLeuvenBelgium

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