Simultaneous Neuronal Activity Measurement Using a Microelectrode Array Recording and Voltage Sensitive Dye Imaging

Abstract

Event Abstract Back to Event Simultaneous Neuronal Activity Measurement Using a Microelectrode Array Recording and Voltage Sensitive Dye Imaging Raeyoung Kim1* and Yoonkey Nam1 1 Korea Advanced Institute of Science and Technology, Dept. of Bio and Brain Engineering, Korea Motivation To study the electrophysiological property of neurons, various measurement techniques have been developed. Microelectrode array (MEA) system is useful for monitoring neuronal network activity in large scale with high temporal resolution. However, it detects extracellular signals generated by the neurons near an electrode so that it is difficult to isolate the source of the signal or the membrane potential variance of each neuron. Optical measurement techniques, such as membrane potential imaging using organic voltage sensitive dyes (VSDs), can supplement the problem of MEA recording since it shows the membrane potential fluctuations in subcellular level. Here, we measured and analyzed the neuronal activity by simultaneous MEA recording and VSD imaging. Material and Methods Hippocampal neurons were dissociated from E18 Sprague Dawley rat embryos and cultured on MEA for more than 14 days (platinum black electrode, diameter 30 ¥ìm, cell density: 1000 cells/mm2). The surface of MEAs was coated with poly-d-lysine. The MEA recording system and VSD imaging system were connected by the TTL signal generated from an sCMOS camera (Andor Neo 5.5 sCMOS) such that the simultaneous recording and imaging were conducted. For MEA recording, the sampling rate was 25 kHz. For membrane potential imaging, Di-8-ANEPPS, a widely used organic VSD, was loaded to cultured neuronal networks. The imaging speed was 1000 frame per second. The field of view was focused on the cell body upon the active electrode of the MEA. The VSD signal was calculated from the relative fluorescence intensity variance and linearly fitted using MATLAB. Results The spontaneous activities of cultured neurons were measured from both MEA recording and VSD imaging simultaneously (figure 1). The electrical signals were in the range of 30 to 140 ¥ìVpp. The optical signals were the averaged fluorescence signal of a cell body, which implies the direct membrane potential change of a neuron. The change of the magnitude of optical signals and the rms noise was around 0.2 % and 0.05%, respectively. The whole view of imaging was 80 x 80 pixel, which was 20 x 20 ¥ìm with a 20x lens. The VSD signals were highly correlated with the burst signals of the MEA. When a burst signal was recorded from the MEA, a VSD signal was also occurred at the same time. In case of a spike signal, a VSD signal was appeared or disappeared depending on the field of view of imaging. Therefore, the source of a spike signal tracing was possible by controlling the imaging site. Subtle optical signals were often detected although no electrical activity was recorded from the MEA. Discussion There was a clear correlation between the electrical signal and the optical signal. A burst signal and a VSD signal occurred simultaneously. Due to the frame rate limitation of the imaging system, which was 1000 Hz at maximum, it was difficult to verify an action potential with precise temporal resolution from optical signals. However, finding a source of a spike was roughly possible by optical signal imaging. Minute VSD signals without accompanying MEA signal should be verified whether they are neuronal signals or not by additional drug tests. Conclusion We were able to measure the neuronal activity by using the two different modalities. There was a high correlation between electrical and optical signals, especially when bursts were generated from the cultured neuronal network. In addition, the spike source verification was possible by changing the imaging site. The simultaneous electrical and optical measurement of neuronal activities will provide additional information which enables profound understanding of the electrophysiological property of neurons. Figure 1. (a) VSD loaded cultured neurons on MEA (b) MEA recording and VSD signal data from the same region of interest (hippocampus, 16 DIV) Figure 1 Acknowledgements This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2015R1A2A1A09003605). Keywords: microelectrode array, Membrane potential imaging, voltage sensitive dye, dissociated culture Conference: MEA Meeting 2016 | 10th International Meeting on Substrate-Integrated Electrode Arrays, Reutlingen, Germany, 28 Jun - 1 Jul, 2016. Presentation Type: Poster Presentation Topic: MEA Meeting 2016 Citation: Kim R and Nam Y (2016). Simultaneous Neuronal Activity Measurement Using a Microelectrode Array Recording and Voltage Sensitive Dye Imaging. Front. Neurosci. Conference Abstract: MEA Meeting 2016 | 10th International Meeting on Substrate-Integrated Electrode Arrays. doi: 10.3389/conf.fnins.2016.93.00007 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 22 Jun 2016; Published Online: 24 Jun 2016. * Correspondence: Dr. Raeyoung Kim, Korea Advanced Institute of Science and Technology, Dept. of Bio and Brain Engineering, Daejeon, Korea, ry_kim@kaist.ac.kr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Raeyoung Kim Yoonkey Nam Google Raeyoung Kim Yoonkey Nam Google Scholar Raeyoung Kim Yoonkey Nam PubMed Raeyoung Kim Yoonkey Nam Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.