Abstract: An optical interface incorporated into a multi-channel telemetry device used principally to provide data representing physiological conditions in a human subject. Information is transmitted without the need of a bio-compatible electrical connection via an optical link which conveys calibration parameters and commands to control the operation of the telemeter. The optical link is configured to reside completely on an integrated circuit chip. Of the three channels designed into the chip by means of appropriate electronic circuitry, one of the channels measures temperature and the other two channels are dedicated to develop generic information selectively derived from other physiological conditions. Calibration information that is programmed into the telemeter by means of the optical interface is retrieved by time division multiplexing with one of the generic channels.

Abstract: A multi-channel circuit for telemetering signals representing physiological values from a point in a human body to a receiver (24) outside of the body. The two signals (S.sub.1, S.sub.2) other than the temperature signal (27') are used to provide two frequency modulated signals (14, 16) summed by an amplifier (18) with the summed FM signal then being applied to amplitude modulate (21) a carrier (8) whose frequency varies as a function of temperature. The resulting FM/AM signal (22) is telemetered inductively outside of the body to an external receiver (24). Appropriate demodulation, filter, and shaping circuits within the external circuit detect the FM signals (14, 16) and thus produce three independent frequencies two of which are the original physiological variables and the third a function of local temperature. Real time plot of the two physiological variables can be obtained using FM discriminators while the temperature dependent frequency is best monitored by a counter.

Abstract: A magnetic nerve stimulator comprises a capacitor which is charged to a high voltage, then discharged through a coil placed near the head. The magnetic field produced induces eddy currents in the brain that stimulate neurons. When the capacitor is fully discharged, the discharge path is broken by opening a switch. The inductive action of the coil forces a diode to turn on and the energy from the collapsing magnetic field around the coil charges a second capacitor. The charge on the second capacitor is augmented by a power source to make up for any losses, and the process is repeated. The stimulator of the invention can pulse rapidly, does not cause excessive heating of the coil, and uses comparatively little energy. As a result, high level cognitive functions in the brain can be disrupted for diagnostic purposes.

Abstract: An apparatus and method for the passive, non-invasive magnetoencephalographic (MEG) localization and tracking of sources of magnetic signals in the brain is disclosed. The apparatus and method uses a multi-axis magnetic gradiometer to detect the magnetic field, field gradient, and polarization emanating from neuronal sources in the brain under either normal or pathological conditions.