Independently movable multielectrode array to record multiple fast-spiking neurons in the cerebral cortex during cognition

Abstract A multiple microelectrode carrier system is described that allows each of 16 microelectrodes in a high-density array to be manipulated in the brain independently by remote control during a cognitive task. Descriptions of the carrier system, advancing techniques, and microelectrode design are presented that allow high-fidelity, extracellular recordings of multiple cerebral cortex neurons with high signal-to-noise ratio and day-to-day repeatability. The motivation for the new carrier system was to provide a method to target multi-microelectrode recordings to a distinct population of fast-spiking neurons in the cerebral cortex during a behavioral task to assess their involvement in selective attention. Recent work using intracellular recording in vitro and single-neuron extracellular recordings in vivo has demonstrated that subpopulations of cortical interneurons can be identified on the basis of their action potential waveform and response to sensory input, and that such interneurons play a fundamental role in generating cortical rhythmicity associated with vigilant wakefulness. A new behavioral paradigm is presented, based on Pavlov’s and Kamin’s classic work on compound conditioning, that permits the electrophysiological patterns of selective attention among neuronal ensembles to be distinguished from those of sensation without attention in a primary sensory cortex. Our approach of multiple, individually guided cerebral cortical recordings in behaving rats during a complex cognitive task is beginning to provide new support for the role of fast cerebral rhythms in selective attention.