Study type: Medical/biological study (experimental study)

Magnetosensory evoked potentials: consistent nonlinear phenomena. med./bio.

Published in: Neurosci Res 2008; 60 (1): 95-105

Aim of study (acc. to author)

To develop and describe a nonlinear signal-processing technique (recurrence quantification analysis) for EEG. Examined were evoked potentials in individual subjects exposed to a magnetic field.

Background/further details

Fifteen subjects were studied (seven males, eight females). There were two periods during which a magnetic field was presented and an intervening period during which no stimulus was applied (sham exposure). The role of the stimulus frequency and vector direction in determining the response were evaluated.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 30–60 Hz
Exposure duration: 50 ms stimulus with an inter-stimulus period of 2.95 s

Exposure 1

Main characteristics
Frequency 30–60 Hz
Type
Waveform
Exposure duration 50 ms stimulus with an inter-stimulus period of 2.95 s
Exposure setup
Exposure source
Setup test person sitting in an isolation chamber; field applied in the coronal or the sagittal plane
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 200 µT effective value - - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

The magnetosensory evoked potentials were independent of the frequency and the direction of the field, and were not detected using the traditional linear method of analysis (time averaging). When the results obtained within subjects were avaraged across subjects, the evoked potentials could not be detected, indicating how real nonlinear phenomena can be averaged away when the incorrect method of analysis is used.
Recurrence quantification analysis, but not linear analysis, permitted consistent demonstration of magnetosensory evoked potentials.

Study character:

Related articles