High Density, Miniaturized, Zero Switching, Stimulation and Recording Headstage for Small Animals

Project Summary Abstract Combining high channel count electrophysiological recording of neural activity with patterned electrical microstimulation has been severely constrained by technical limitationsForemost among these limitations are the problems associated with simultaneous recording and micro stimulationStimulation artifacts are up to four orders of magnitude larger than the neural signal being sensedThe large signal drives the amplifiers outside of their linear range and traditional AC coupled amplifiers require long settling times to recoverThese long settling times are due to long time constants created by low frequency high pass filtersOne traditional approach to avoid amplifier saturation is to employ switches for electrodeheadstage amplifierand stimulator connections to rapidly switch between recording and stimulationSwitches must be employed to disconnect the stimulator when recording to avoid amplifier saturation and degrading the high impedance electrode signal from parasitic cable capacitances and interference sourcesThis project will develop a research tool for neuroscientists that will achieve electrical stimulation and neural signal recording from the same microelectrodeMultiple channels of simultaneous recording and micro stimulation from the same electrode are combined on the same integrated circuitICfor integration in a headstageThe integration in an IC eliminates signal degradation and interference from cabling and switching parasitic effectsAdditionallythe low noise amplifier circuitrystimulation circuitry and local control may be intimately tied to mitigate the electrode polarization recovery Project Narrative A greater understanding of the neuronal mechanisms underlying cognitive function is unlikely to emerge until several technical hurdles can be overcomeNew instruments are needed to characterize the relationships between cognitive behaviors and the spatiotemporal patterns of neuronal activity in the distributed circuits that mediate those behaviorsThese approaches must be combined with the ability to make specific and targeted manipulations of neuronal activity to establish causal physiological links between behavior and network dynamics