Large-Scale Juxtacellular Recordings from Cultured Hippocampal Neurons by an Array of Gold-Mushroom Shaped Microelectrodes
The Hebrew University of Jerusalm, Neurobiology, Israel
Extracellular recordings by substrate integrated planar microelectrode arrays (MEAs) are considered the "gold standard" for millisecond-resolution, long-term, large-scale, cell noninvasive electrophysiological recordings and stimulation of in vitro and in vivo neuronal networks. Although planar MEA platforms are used extensively, they suffer from a low signal to noise ratio and low source resolution. These drawbacks are solved by tedious spike-detecting, spike-sorting and signal averaging techniques which rely on estimated parameters and require user supervision to correct errors, merge clusters and remove outliers. Averaging of recorded field potentials (FPs) leads to loss of essential information as to the relevance of changes in FPs shapes, amplitudes and patterns over short or long experimental sessions as well as in relations to behavioral tasks. Planar electrode-based MEA are "blind" to sub-threshold synaptic potentials generated by individual neurons. The neglect of silent neuron, due to the technical limitation of currently used planar MEA goes on in spite of clear documentation that meaningful subthreshold signaling between neighboring neurons plays a critical role in neuronal network computations. In recent years our laboratory has developed a new approach in which micrometer-sized, extracellular gold mushroom-shaped microelectrodes (gMµEs) record attenuated synaptic and action potentials with characteristic features of intracellular recordings (the IN-CELL recording method). Earlier attempts by our laboratory to apply the IN-CELL recordings method to cultured mammalian neurons by gMµEs-MEAs were only partially successful. In the present study, we report on the progress made in applying gMµE-MEA for multisite recordings from cultured mammalian neurons. Embryonic rat hippocampal neurons grown on micrometer size gold mushroom-shaped microelectrode array (gMµE-MEA) simply functionalized by poly-ethylene-imine/laminin undergo a process to form juxtacellular junctions between the neurons and the gMµEs. Hippocampal neurons grown on gMµE-MEA revealed sporadic spontaneous activity from day 7 DIV. Bursting activity was detected from day 10 onward as described in earlier studies using substrate integrated planar MEA. The most striking difference between the recordings of APs by planar MEA and the gMµE-MEA is that whereas substrate integrated planar MEA record FPs dominated by negative-peak or biphasic-signals with amplitudes typically ranging between 40-100 µV and a signal to noise ratio of ≤ 5, the gMµE-MEA recordings were dominated by positive monophasic action potentials. It is important to note that monophasic high peak amplitudes ≥ 100 µV are rarely obtained using planar electrodes arrays, whereas when using the gMµE-MEA, 34.48 % of the gMµEs recorded potentials ≥ 200 µV and 10.64 % recorded potentials in the range of 300-5,085 µV. Computer simulations of the passive analog electrical circuits depicting the neuron-gMµE juxtacellular junction predicted that in addition to positive action potentials, barrages of large synaptic potentials (~10mV) are expected to be read in the form of 100-200 µV membrane ripples. Although not conclusive some of the electrophysiological observations were consistent with reflecting such synaptic activity. This study was supported by the EU FP7 Future Emerging Technology program, a "BRAINLEAP" grant No. 306502 and The C. Smith Family and Prof. J. Elkes Laboratory for Collaborative Research in Psychobiology
gold mushroom-shaped microelectrode
MEA Meeting 2016 |
10th International Meeting on Substrate-Integrated Electrode Arrays, Reutlingen, Germany, 28 Jun - 1 Jul, 2016.
MEA Meeting 2016
(2016). Large-Scale Juxtacellular Recordings from Cultured Hippocampal Neurons by an Array of Gold-Mushroom Shaped Microelectrodes.
MEA Meeting 2016 |
10th International Meeting on Substrate-Integrated Electrode Arrays.
22 Jun 2016;
24 Jun 2016.