A simultaneous optical and electrical in-vitro neuronal recording system to evaluate microelectrode performance

Abstract

Objectives In this paper, we aim to detail the setup of a high spatio-temporal resolution, electrical recording system utilising planar microelectrode arrays with simultaneous optical imaging suitable for evaluating microelectrode performance with a proposed ′performance factor′ metric. Methods Techniques that would facilitate low noise electrical recordings were coupled with voltage sensitive dyes and neuronal activity was recorded both electrically via a customised amplification system and optically via a high speed CMOS camera. This technique was applied to characterise microelectrode recording performance of gold and poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT/PSS) coated electrodes through traditional signal to noise (SNR) calculations as well as the proposed performance factor. Results Neuronal activity was simultaneously recorded using both electrical and optical techniques and this activity was confirmed via tetrodotoxin application to inhibit action potential firing. PEDOT/PSS outperformed gold using both measurements, however, the performance factor metric estimated a 3 fold improvement in signal transduction when compared to gold, whereas SNR estimated an 8 fold improvement when compared to gold. Conclusion The design and functionality of a system to record from neurons both electrically, through microelectrode arrays, and optically via voltage sensitive dyes was successfully achieved. Significance The high spatiotemporal resolution of both electrical and optical methods will allow for an array of applications such as improved detection of subthreshold synaptic events, validation of spike sorting algorithms and a provides a robust evaluation of extracellular microelectrode performance.

Imaging the Efficiency of Poly(3,4‐ethylenedioxythiophene) Doped with Acid‐Functionalized Carbon Nanotube and Iridium Oxide Electrode Coatings for Microstimulation

“…By coating CPs onto metal substrates, we have drastically reduced electrical impedance and improved neurophysiological recording capabilities. [ 31 , 32 , 33 , 34 , 35 , 36 ] The increased electrochemical surface area and decreased impedance make PEDOT an ideal candidate for electrical stimulation. [ 37 , 38 , 39 , 40 , 41 , 42 ] Functionalized carbon nanotubes (CNTs) have been increasingly popular for their intriguing properties as a dopant for PEDOT.…”

A Subdural Bioelectronic Implant to Record Electrical Activity from the Spinal Cord in Freely Moving Rats

“…These differences in spike magnitude may be related to varying distance between source and electrode. [ 36 ] Similarly, Figure 6d shows lower amplitude voltage spikes that are localized to individual channels. Figure 6e shows repetitive voltage spikes that reach between ≈1 and 2 mV below the baseline and oscillate in rapid succession.…”

“…These differences in spike magnitude may be related to varying distance between source and electrode. [36] Similarly, Figure 6d shows lower amplitude voltage spikes that are localized to individual channels. Figure 6e…”

Electrical activity recorded from the spinal cord in freely moving rats using a subdural bioelectronic implant

“…The electrical activity varies greatly in magnitude with a few higher amplitude spikes evident in the range of 1 – 6 mV, whereas the majority of signals have an amplitude below 2 mV. These differences in spike magnitude may be related to varying distance between source and electrode ( 27 ). Three characteristic voltage waveforms were observed throughout the recording ( Figure 8B ).…”