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At least 1,099 records · Page 61Linked to original sources
PubMed1995

A simple and reliable method for construction of parallel multibarrel microelectrodes.

A modification to the method of construction of parallel or "piggy-back" electrodes for extracellular single-unit recording combined with iontophoresis is described that facilitates the alignment of the two components of the array. The method involves the use of an orthogonal viewing device (a pair of mirrors mounted symmetrically at 45 degrees to the horizontal), which produces a pair of virtual images of the electrode components that can be viewed with a microscope. A slight displacement between the electrodes is easily detected as an uneven separation between the electrode images. The positions of the electrode components are adjusted until there is no visible separation of the electrodes or their virtual images.

Animals↗
PubMed2006

Microelectrode recording can be a good adjunct in magnetic resonance image-directed subthalamic nucleus deep brain stimulation for parkinsonism.

BACKGROUND: The contribution of MER to improving bilateral STN-DBS is debatable. To resolve the controversy and elucidate the role of MER in DBS, we compared the outcome of bilateral STN-DBS surgery with and without MER in parkinsonian patients. METHODS: From February 2002 to November 2002, the first 7 of 13 consecutive parkinsonian patients received STN-DBS without MER (group A), and the last 6 received STN-DBS with MER (group B). Pre- and postoperative assessments included scoring of UPDRS with video taping, and MR images. RESULTS: The mean Hoehn and Yahr stage was 3.6 in group A and 4.0 in group B. The mean follow-up was 7.4 months for group A and 5.3 months for group B. The mean coordinates of the tip of the permanent electrode relative to the mid-commissural point were x = 8.1 mm, y = 4.3 mm, and z = 5.9 mm for group A and x = 10.6 mm, y = 4.1 mm, and z = 6.9 mm for group B. When levodopa was withdrawn from group A for 12 hours at follow-up, the postoperative UPDRS total score improved by 27.6% (P = .01) and the motor score by 25.4% (P = .02); their LEDD decreased by 17.5% (P = .03). In group B, the postoperative UPDRS total score improved by 49.3% (P = .00002) and the motor score by 45.2% (P = .0004); LEDD decreased by 48.5% (P = .01). CONCLUSIONS: Although STN-DBS is a promising surgical modality for advanced parkinsonian patients, there is an inevitable learning curve associated with adopting this new procedure. Intraoperative MER is an effective way to ensure correct electrode placement in the STN. With the assistance of intraoperative MER, the outcome of STN-DBS can be improved significantly.

Aged↗
PubMed2001

Acute toxicity screening of novel AChE inhibitors using neuronal networks on microelectrode arrays.

Spontaneously active neuronal networks grown from embryonic murine frontal cortex on substrate integrated electrode arrays with 64 recording sites were used to assess acute neurobiological and toxic effects of a series of seven symmetrical, bifunctional alkylene-linked bis-thiocarbonate compounds designed to possess anticholinesterase activity. Acute functional neurotoxicity in the absence of cytotoxicity was defined as total collapse of spontaneous activity. All of the compounds were characterized as mixed inhibitors of AChE, with K(i)'s in the 10(-7)-10(-6) M range. The neuronal network assays revealed high repeatability for each compound, but surprisingly diverse effects among these closely related compounds. Six of the seven compounds produced changes in network activity at concentrations of 10-350 microM. Three of the compounds were excitatory, two were biphasic (excitatory at lower concentrations, inhibitory at higher), and one was solely inhibitory. Two of the inhibitory compounds produced irreversible inhibition of activity. Responses of cortical cultures to eserine were compared to the effects produced by the test compounds, with only one of seven providing a close match to the eserine profile. Matching of response patterns allows the classification of new drugs according to their response similarity to well-characterized agents. Spontaneously active neuronal networks reflect the interactions of multiple neurotransmitter and receptor systems, and can reveal unexpected side effects due to secondary binding. Utilizing such networks holds the promise of greater research efficiency through a more rapid recognition of physiological tissue responses.

Animals↗
PubMed2001

Multiple microelectrode-recording system for human intracortical applications.

The human brain is dominated by the neocortex, a large folded surface, whose cellular and synaptic elements are arranged in layers. Since cortical structure is relatively constant across its surface, local information processing can be inferred from multiple laminar recordings of its electrical activity along a line perpendicular to its surface. Such recordings need to be spaced at least as close together as the cortical layers, and need to be wideband in order to sample both low frequency synaptic currents as well as high-frequency action potentials. Finally, any device used in the human brain must comply with strict safety standards. The current paper presents details of a system meeting these criteria, together with sample results obtained from epileptic subjects undergoing acute or chronic intracranial monitoring for definition of the epileptogenic region.

Action Potentials↗
PubMed1996

A novel carbon fiber bundle microelectrode and modified brain slice chamber for recording long-term multiunit activity from brain slices.

The fabrication and characteristics of a novel multiunit recording electrode and modified brain slice chamber suitable for long-term recording from brain slices are described. The electrode consisted of an electrolyte-filled glass micropipette with a 20-50 microns thick wax-coated bundle of 5-micron diameter carbon fibers extending 2.5 cm from the tapered end and an AgCl-coated silver wire inserted into the open end and connected to a preamplifier. Both ends of the electrode were sealed with wax to prevent evaporation of the electrolyte. The brain slice was maintained over this extended period in an interface-type brain slice chamber modified to completely surround the slice with medium. Using this electrode, regular 24-h oscillations of spontaneous multiunit activity were recorded for 3 days from a single location in a 500 microns thick rat suprachiasmatic nucleus brain slice. Preliminary data suggest that this novel carbon fiber bundle electrode will be a favorable alternative to traditional metal electrodes for long-term recording of multiunit activity from brain slices.

Animals↗
PubMed1996

Metallized polymer fibers as leadwires and intrafascicular microelectrodes.

We have developed a process for producing fine, very flexible microwires suitable for use as small signal leadwires or nerve electrodes. The process incorporates metallization of high-performance monofilament polymer fibers to yield electrically conductive fibers with greatly improved flexibility over solid metal wires of similar strength. The metallization layers are produced by serial vacuum deposition of a 0.3 micron thick coating of three metals, titanium-tungsten (Ti/W), gold (Au), and platinum (Pt), onto monofilament, poly-p-phenyl-terephthalate aramid fibers (Kevlar). The metallized fibers are then insulated with an approx. 1 micron thick layer of silicone elastomer. The result is a microlead with high electrical conductivity (linear resistance = 30 omega/cm), desirable interfacial properties, excellent mechanical stability and extremely high flexibility. These physical characteristics are appropriate for application as signal leadwires or recording/stimulating electrodes where small size and high flexibility are paramount. In this paper we report on the electrical and mechanical properties of these metallized fibers and demonstrate their use as intrafascicular electrodes for recording multi-unit neural activity in feline peripheral nerves.

Animals↗