Implantable microelectrode arrays for simultaneous electrophysiological and neurochemical recordings

Abstract

Implantable microfabricated microelectrode arrays represent a versatile and powerful tool to record electrophysiological activity across multiple spatial locations in the brain. Spikes and field potentials, however, correspond to only a fraction of the physiological information available at the neural interface. In urethane-anesthetized rats, microfabricated microelectrode arrays were implanted acutely for simultaneous recording of striatal local field potentials, spikes, and electrically-evoked dopamine overflow on the same spatiotemporal scale. During these multi-modal recordings we observed 1) that the amperometric method used to detect dopamine did not significantly influence electrophysiological activity, 2) that electrical stimulation in the medial forebrain bundle (MFB) region resulted in electrochemically-transduced dopamine transients in the striatum that were spatially heterogeneous within at least 200 µm, and 3) following MFB stimulation, dopamine levels and electrophysiological activity within the striatum exhibited similar temporal profiles. These neural probes are capable of incorporating customized microelectrode geometries and configurations, which may be useful for examining specific spatiotemporal relationships between electrical and chemical signaling in the brain.

Real-time simultaneous recording of electrophysiological activities and dopamine overflow in the deep brain nuclei of a non-human primate with Parkinson’s disease using nano-based microelectrode arrays

“…However, the connections between the chemical transmitters and electrical activities are still not well understood in vivo. Therefore, dual-mode detection of PD-related neuroelectrical and neurochemical information is essential for pathologic research, early diagnosis, therapeutic effect assessments, and new treatment developments of the disease 17,18 . Previous neural information detections in parkinsonian animal models were based on traditional implantable devices.…”

An implantable microelectrode array for simultaneous L-glutamate and electrophysiological recordings in vivo

“…The centre-tocentre site separation was 170 μm between two adjacent electrochemical sites, 80 μm between two adjacent electrophysiological sites, and 150 μm between an electrophysiological site and an adjacent electrochemical site. Maintaining a 50-200 μm distance between recording sites was reasonable as a shorter inter-electrode separation could result in possible crosstalk artefacts, whereas a larger separation would miss cross-correlations between neuron pairs 18,34 . The MEA probe was wire bonded to a printed circuit board (PCB) holder for handling and connecting to the recording equipment ( Figure 1b).…”

“…Local field potential (LFP) integrates predominantly synaptic input signals from a large population of neurons, whereas spikes or action potentials are output signals of a single neuron [15][16][17] . Thus, investigating the extracellular electrophysiological signals corresponding to these activities may enable better understanding of glutamatergic processes 16,18 .…”

Nanostructured Coatings for Improved Charge Delivery to Neurons

“…As described in an earlier chapter, nanostructured coatings on metals like platinum and iridium can be used to detect neurotransmitters and pH in the brain [137,149,150]. These detection methods utilize a small electrical potential to detect redox reactions of target molecules at the surface of the microelectrode.…”