Human Threshold Research Group and Testing Facility

This research group and facility, associated with the Bioelectromagnetics (BEMS) group has an international reputation and expertise in research regarding the biological effects of low frequency time-varying magnetic field (MF) exposures in humans.

The group is studying magnetic field levels higher than to what the general population is usually exposed, using mathematical modeling to simulate the potential effects on the human brain. 

For instance, using a multimodality experimental approach, we have suggested an effect of 1.8 and 3 mT 60 MF on neuroprocessing in humans (via synaptic plasticity). These results are being used by international agencies such as ICNIRP (International Commission on Non-Ionizing Radiation Protection) to develop and support international guidelines regulating human exposure to electromagnetic fields. Current projects are investigating thresholds for systematic neurophysiological responses in humans using stimuli at 20, 50, 60 and 100 Hz of up to 50 mT (high enough to induce flickering visual perception called magnetophosphenes).

These are pictures, showing on the far left, our global head exposure system (top) with a scaled coronal view of a human anatomical image superimposed to the corresponding field distribution (bottom). The head of the subject is exposed to a homogeneous 50 mT MF (5 mT contour lines). On the immediate left our local exposure coil is presented (top) with a scaled representation of a human head transversal slice superimposed to the field distribution (bottom). In this example, the eyeball is non-homogeneously exposed to 50 mT. Both these human exposure devices are CSA Medical Grade approved. 

The group continues to strengthen and extend its fundamental research effort, and new projects aiming to establish thresholds at which a systematic neurophysiological response is induced by a magnetic stimulus are being developed and initiated. For instance, our current projects are successfully establishing the threshold for human magnetophosphene perception, and new developments targeting the investigation of exposures of up to 100 mT on the human vestibular system are in process.

This scientific expertise now allows us to investigate, in association with the Bioelectromagnetics group, the potential avenues of translational applications targeting symptom improvements in movement disorders such as in Parkinson’s disease. With this strategy, we have been successful with the St. Joseph's Foundation in the acquisition of a state of the art Transcranial Magnetic Stimulation (TMS) system with Neuronavigation capability, and we have been successful in recruiting Dr. Julien Modolo as a Scientist at Lawson.

Neurocomputational modeling is being promoted as a new promising window to understand the underlying electromagnetic interactions; for example, this modeling approach offers a mechanistic hypothesis supporting reported effects on synaptic plasticity. Both these experimental and theoretical insights are integrated within an emerging research effort; potential translation to therapeutic strategies in neuromotor disorders.

This facility is also available on contract to test other stimuli and for patient/study diagnostic use as a wide-range test facility for human sensory/motor and neurocognitive testing. The facility contains a wide assortment of testing capability all housed within an available hypoxia-controlled (monitored artificial hypoxic atmosphere to 4500m altitude) environment. Equipment includes 32 channel ambulatory EEG, 64 and 128 channel fixed-lead EEG/EMG, 6 degrees-of-freedom force plate, 16 channel Polhemus, fingertip micro-tremor monitoring, HR, BOP, audio/video, PC-controlled psychometrics, hot/cold neurosensory stimulation.  Most of the above equipment, including a 128 channel EEG/EMG, is also available within our 3T mMR/PET/EEG/EMG hybrid imaging facility.

Investigators
Alexandre Legros, PhD, BEMS, Kinesiology, Director
Julien Modolo, PhD, Computational Neuroscience
Alex Thomas, PhD, BEMS, Co-leader

Collaborators
Lynn Keenliside, Medical Device Prototyping
Frank Prato, PhD, Imaging Director/Physicist Chief
Robert Stodilka, PhD, Nuclear Medicine Physics
Jean Théberge, PhD, Magnetic Resonance Physics
Terry Thompson, PhD, MR Spectroscopy