1,720,974 research outputs found
A low-noise, modular, and versatile analog front-end intended for processing in vitro neuronal signals detected by microelectrode arrays
Full text linkThe collection of good quality extracellular neuronal spikes from neuronal cultures coupled to Microelectrode Arrays (MEAs) is
a binding requirement to gather reliable data. Due to physical constraints, low power requirement, or the need of customizability,
commercial recording platforms are not fully adequate for the development of experimental setups integrating MEA technology
with other equipment needed to perform experiments under clima
te controlled conditions, like environmental chambers or cell
culture incubators. To address this issue, we developed a custom MEA interfacing system featuring low noise, low power, and
the capability to be readily integrated inside an incubator-like environment. Two stages, a preamplifier and a filter amplifier, were
designed, implemented on printed circuit boards, and tested. The system is characterized by a low input-referred noise (
<
1
휇
V
RMS), a high channel separation (
>
70 dB), and signal-to-noise ratio values of neuronal recordings comparable to those obtained
with the benchmark commercial MEA system. In addition, the system was successfully integrated with an environmental MEA
chamber, without harming cell cultures during experiments and without being damaged by the high humidity level. The devised
system is of practical value in the development of
in vitro
platforms to study temporally extended neuronal network dynamics by
means of MEAs
Development of a custom front-end for long-term multichannel recordings of in vitro neuronal activity
No full textA framework for the comparative assessment of neuronal spike sorting algorithms towards more accurate off-line and on-line microelectrode arrays data analysis
Full text linkNeuronal spike sorting algorithms are designed to retrieve neuronal network activity on a single-cell level from extracellular multiunit recordings with Microelectrode Arrays (MEAs). In typical analysis of MEA data, one spike sorting algorithm is applied indiscriminately to all electrode signals. However, this approach neglects the dependency of algorithms' performances on the neuronal signals properties at each channel, which require data-centric methods. Moreover, sorting is commonly performed off-line, which is time and memory consuming and prevents researchers from having an immediate glance at ongoing experiments. The aim of this work is to provide a versatile framework to support the evaluation and comparison of different spike classification algorithms suitable for both off-line and on-line analysis. We incorporated different spike sorting "building blocks" into a Matlab-based software, including 4 feature extraction methods, 3 feature clustering methods, and 1 template matching classifier. The framework was validated by applying different algorithms on simulated and real signals from neuronal cultures coupled to MEAs. Moreover, the system has been proven effective in running on-line analysis on a standard desktop computer, after the selection of the most suitable sorting methods. This work provides a useful and versatile instrument for a supported comparison of different options for spike sorting towards more accurate off-line and on-line MEA data analysis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The Influence of Neuronal Density and Maturation on Network Activity of Hippocampal Cell Cultures: A Methodological Study
No full textIt is known that cell density influences the maturation process of in vitro neuronal networks. Neuronal cultures plated with different cell densities differ in number of synapses per neuron and thus in single neuron synaptic transmission, which results in a density-dependent neuronal network activity. Although many authors provided detailed information about the effects of cell density on neuronal culture activity, a dedicated report of density and age influence on neuronal hippocampal culture activity has not yet been reported. Therefore, this work aims at providing reference data to researchers that set up an experimental study on hippocampal neuronal cultures, helping in planning and decoding the experiments. In this work, we analysed the effects of both neuronal density and culture age on functional attributes of maturing hippocampal cultures. We characterized the electrophysiological activity of neuronal cultures seeded at three different cell densities, recording their spontaneous electrical activity over maturation by means of MicroElectrode Arrays (MEAs). We had gather data from 86 independent hippocampal cultures to achieve solid statistic results, considering the high culture-to-culture variability. Network activity was evaluated in terms of simple spiking, burst and network burst features. We observed that electrical descriptors were characterized by a functional peak during maturation, followed by a stable phase (for sparse and medium density cultures) or by a decrease phase (for high dense neuronal cultures). Moreover, 900 cells/mm(2) cultures showed characteristics suitable for long lasting experiments (e.g. chronic effect of drug treatments) while 1800 cells/mm(2) cultures should be preferred for experiments that require intense electrical activity (e.g. to evaluate the effect of inhibitory molecules). Finally, cell cultures at 3600 cells/mm(2) are more appropriate for experiments in which time saving is relevant (e.g. drug screenings). These results are intended to be a reference for the planning of in vitro neurophysiological and neuropharmacological experiments with MEAs
Selective Biochemical Manipulation of Twin Neuronal Networks on Microelectrode Arrays
No full textComparability of responses to neuroactive compounds and spatially and temporally resolved delivery of soluble factors are two major key features for pharmacological assays. Here, we describe the fabrication and the use of a device for long-term growth of twin neuronal networks and for their controlled biochemicalstimulation. The device is formed by a PDMS microfl uidic chamber coupled to a fl at Microelectrode Array (MEA), which provides the electrophysiological readout of the pharmacological stimulation. A partial physical barrier divides the chamber in two sub-compartments, where two functionally independent but fl uidically connected neuronal networks can be grown. This platform improves biological comparability between cultures and allows to perform selective and temporally controlled stimulations to neurons, running parallel pharmacological tests on the same device
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