Circuit Models and Experimental Noise Measurements of Micropipette Amplifiers for Extracellular Neural Recordings from Live Animals
Figure 1
(a) Equivalent circuit model of a micropipette used for in vivo extracellular neural recordings of conscious animals. : neural voltage of target neuron; : neural voltage of non-target neurons; : equivalent resistance between target neuron and the micropipette tip; : equivalent resistance between nontarget neurons and the micropipette tip; : equivalent resistance between the micropipette tip and the ground; : micropipette tip voltage; : liquid junction potential and half-cell potential; : distributed resistance of the electrolyte; : equivalent capacitance of the glass pipette wall; : overall input impedance of the amplifier; : input voltage of the amplifier. (b) Illustrations of using a sharp micropipette and a blunt micropipette. (c) Equivalent noise model of a glass micropipette connected to a neural amplifier. (: thermal noise generated from equivalent resistor between target neuron and the micropipette tip; : noise generated from nontarget neurons; : thermal noise generated from equivalent resistor between the micropipette tip and the ground; : dielectric noise of the micropipette wall; : environmental noise; : thermal noise generated by the distributed resistance of the electrolyte; : intrinsic noise of the neural amplifier; : equivalent impedance between the amplifier and the power line. : total noise of the micropipette neural amplifier).
