Journal of neuroscience methods
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J. Neurosci. Methods · Jun 2008
Multicenter StudyDefault mode network as revealed with multiple methods for resting-state functional MRI analysis.
Recently, human brain activity during a resting-state has attracted increasing attention. Several studies have found that there are two networks: the default mode network and its anti-correlation network. Some studies have subsequently showed that the functions of brain areas within the default mode network are crucial in human mental activity. ⋯ Our results showed the existence of these two networks prominently and consistently during a resting- and conscious-state across the three methods. This consistency was exhibited in four independent groups of normal adults. Moreover, the current results provided evidences that the brain areas within the two anti-correlated networks are highly integrated at both the intra- and inter-regional level.
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J. Neurosci. Methods · Jun 2008
A voltage-controlled current source with regulated electrode bias-voltage for safe neural stimulation.
A current source for neural stimulation is presented which converts arbitrary voltage signals to current-controlled signals while regulating the offset-voltage across the stimulation electrodes in order to keep the electrodes in an electrochemical state that allows for injecting a maximum charge. The offset-voltage can either be set to 0V or to a bias-voltage, e.g. of a few 100mV, as it can be advantageous for fully exploiting the charge injection capacity of iridium oxide electrodes.
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J. Neurosci. Methods · May 2008
A novel stimulus artifact removal technique for high-rate electrical stimulation.
Electrical stimulus artifact corrupting electrophysiological recordings often makes the subsequent analysis of the underlying neural response difficult. This is particularly evident when investigating short-latency neural activity in response to high-rate electrical stimulation. We developed and evaluated an off-line technique for the removal of stimulus artifact from electrophysiological recordings. ⋯ This technique required only that artifact events be identifiable and that the artifact duration remained less than both the inter-stimulus interval and the time course of the action potential. We have demonstrated that this computationally efficient sample-and-interpolate technique removes the stimulus artifact with minimal distortion of the action potential waveform. We suggest that this technique may have potential applications in a range of electrophysiological recording systems.
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J. Neurosci. Methods · May 2008
Automatic positioning and sensing microelectrode array (APSMEA) for multi-site electrophysiological recordings.
Technological improvement of measurements for the electrical recordings from individual neurons within network is essential in neuroscience today. Here, we present a novel automatic positioning and sensing microelectrode array (APSMEA), which simultaneously positioned desired number of neurons onto 48 recording microelectrodes automatically and scathelessly by use of negative dielectrophoretic (DEP) forces, and facilitated the measurement of the electrophysiological activities of neuronal populations after functional synaptic connections formed between neurons. The results of multi-site electrophysiological recordings during drug administration also demonstrated the application of APSMEA in bioassay with cultured rat cortical neurons. Therefore, this device should benefit the investigation of neuronal networks in vitro with more comprehensive electrophysiological experiments, and also promise the possibility of a modular device for both cell manipulation and cell-based biosensor on microchip.
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J. Neurosci. Methods · May 2008
Identifying repeating motifs in the activation of synchronized bursts in cultured neuronal networks.
Cultured neuronal networks cultivated on micro-electrode arrays are a widely used tool for the investigation of network mechanisms, providing structural framework for long-term recordings of network electrical activity, as well as the network reaction to electrical or chemical stimulations. The typical activity pattern of the culture takes the form of synchronized bursting events (SBEs), in which a large fraction of the recorded neurons simultaneously fire trains of action potentials in short bursts of several hundreds of a millisecond. We developed a method that identifies clusters of bursts that share a similar activation motif throughout the culture based on the fact that the culture morphology remains relatively unchanged for an extended time interval and that neurons fire in a recognizable and precise manner during a burst initiation. ⋯ Clustered networks showed more motifs on average than uniform cultures. The algorithm was able to show high fidelity to artificial noise. We also compare the results of our method with another method based on a correlation measure.