Let me begin by noting that Australia's duck-bill platypus hunts by sensing the faint electrical impulses generated by their prey. If I can find where I've written down that research, I'll post it.
------
Both the eye and brain generate magnetic fields when stimulated with a variety of visual cues. These magnetic fields can be measured with a magnetometer; a device which uses superconducting technology. Magnetic field variation from the human brain produced by visual stimulation have been observed in a normal laboratory setting with a superconducting quantum interference device and no magnetic shielding of the subject. Previously unknown temporal and spatial features of the field near the scalp are reported [(1975)].
With the development of multichannel magnetoencephalographs biomagnetic signals can be recorded over large areas at the same time. It allows determination of the magnetic field outside the head. The technology works by measuring the extremely faint magnetic fields producted when nerve cells in the brain fire electrical signals to communicate one another. Biomagnetometers, which look like…beauty-parlor hair dryers, measure brain-generated magnetic fields that are one ten-millionth the strength of Earth's magnetic field. The biomagnetic signals originating from a[]…discharge is, however, mixed with biomagnetic signals generated by the background activity in the brain.
A long auditory stimulus [also] elicits a magnetic evoked response in the human brain, consisting of transient deflections followed by a sustained response. The distributions of the magnetic fields indicate that the auditory evoked transient response at a latency of 100 ms as well as the auditory sustained response are generated at and around the primary auditory cortex. These fields exhibit features with a clear spatial symmetry which can be accounted for by assuming that their source consists of two vertically oriented neuronal complexes symmetrically located deep in the temporal lobes. This assignment, which is also consistent with the available electrical data, places the sources within the auditory cortex near the sylvian fissure.
In…right-handed male adults,…[when] stimulating the right ear the averaged magnetic field from the left hemisphere is approx. twice as great as that from the right hemisphere, whereas stimulating the left ear no difference in magnitude is found. The responses from contralateral stimulation are approx. 9 ms earlier than those from ipsilateral stimulation with no interhemispheric differences. [When] the component of the magnetic field normal to the skull was measured; in some cases this component was oriented in the outward direction (group 1 and some group 2 subjects), in the other cases in the inward direction (group 2).
By recording the magnetic field of the human brain while simultaneously presenting light to the eye and sound to the ear we have identified a brain region where auditory and visual signals converge. The location of this region is close to primary auditory cortex and far from primary visual cortex.
magnetoencephalography, Richard P. Brennan, Dictionary of Scientific Literacy, (NY: John Wiley & Sons, Inc., 1992).
Op. cit.