Abstract A means for monitoring electrophysiological activity is described having electrodes connected to an animal body with the output therefrom coupled to an amplifier which in turn feeds the amplified physiologically generated signal to a band pass filter network. The band pass filter is adapted to pass only those portions of the signals from the electrodes which occur in a predetermined frequency band. The filtered signal is coupled to an absolute value detector which produces a unidirectional output current signal the instantaneous amplitude of which corresponds to the instantaneous amplitude of the filter output signals. The detector output signal is coupled to a reversible microcoulometer which plates a metal from one electrode to another. The plating activity of the reversible microcoulometer produces a mass of plated material which is equivalent to the current-time integral, hence the average value, of the filter output signal. A readout device may be provided which causes the microcoulometer to operate in a reverse direction at a predetermined flow rate thereby causing a current of a predetermined value to flow. The value of the current-time integral may then be determined by determining the time required for the microcoulometer to operate in the reverse direction at the known current value. As an alternative, an event detection means may be provided which receives the signal from the electrodes and produces an output current signal of a known amplitude and duration or any signal producing a fixed, known charge for each occurrence of a predetermined wave form. In this mode of operation the reversible microcoulometer in effect operates as a counter with the amount of plating being equivalent to the number of occurrences of the predetermined wave form.
Apparatus for obtaining a quantitative measure of electrophysiological activity in a predetermined frequency band comprising means for receiving a physiologically generated electrical signal, filter means electrically connected to said means for receiving to provide a filtered output signal which consists of only those frequency components of said received signal occurring within a predetermined band of frequencies, detector means electrically connected to said filter means for receiving said filtered output signal and for producing a unidirectional electrical current output signal, the instantaneous amplitude of said output current signal being proportional to the instantaneous amplitude of said filtered output signal, said detector means comprising a rectifier means for accomplishing half wave rectification of said filter output signal, summing means for adding said half wave rectified signal to said filter output signal and means for producing from said added signal a current signal having an amplitude equal to the negative of twice the amplitude of said half wave rectified signal plus the negative of the amplitude of said filter output signal, and integrating means electrically connected to said detector means for receiving said output current signal and generating a quantum equivalent to the time integral of said detector output current signal and for indefinitely storing said quantum.
Claim 2
Dependent Claim
204 words
Apparatus for obtaining a quantitative measure of electrophysiological activity in a predetermined frequency band comprising means for receiving a physiologically generated electrical signal, filter means electrically connected to said means for receiving to provide a filtered output signal which consists of only those frequency components of said received signal occurring within a predetermined band of frequencies, detector means electrically connected to said filter means for receiving said filtered output signal and for producing a unidirectional electrical current output signal, the instantaneous amplitude of said output current signal being proportional to the instantaneous amplitude of said filtered output signal, said detector means comprising a rectifier means for accomplishing half wave rectification of said filter output signal, summing means for adding said half wave rectified signal to said filter output signal and means for producing from said added signal a current signal having an amplitude equal to the negative of twice the amplitude of said half wave rectified signal plus the negative of the amplitude of said filter output signal, and integrating means electrically connected to said detector means for receiving said output current signal and generating a quantum equivalent to the time integral of said detector output current signal and for indefinitely storing said quantum.