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Topic: Extracellular field potential

	Extracellular field potential - Wikipedia, the free encyclopedia
		The extracellular field potential is the electrical potential produced by cells, e.g.
		In these experiments the extracellular field potential will be detected as an electrical potential whose source and composition is often ambiguous, making its interpretation difficult.
		For individual cells, the time course of the extracellular potential theoretically is inversely proportional to the transmembrane current.
	en.wikipedia.org /wiki/Extracellular_field_potential (203 words)

	Physiological origins of evoked magnetic fields and extracellular field potentials produced by guinea-pig CA3 ...
		Extracellular currents were not considered in the present analysis since their contribution to the magnetic field was negligible in a mathematical model in which the assumption of isopotential in the revised model was removed and the extracellular potentials were explicitly calculated (S. Murakami and Y. Okada, unpublished results).
		Field potentials were measured along the longitudinal axis of the pyramidal cells with respect to the soma (units in µm, basal negative).
		Empirically, the field potentials close to a pair of stimulating electrodes (direct stimulation) exhibited a negative extracellular potential between 1 and 4 ms in the apical region and a corresponding negativity in the soma region, indicating a dipolar current.
	jp.physoc.org /cgi/content/full/544/1/237 (10065 words)

	Tetrode - Wikipedia, the free encyclopedia
		A tetrode is a group of wire bundles used in electrophysiological studies in the neurosciences to record extracellular field potentials from nervous tissue, e.g.
		The idea is that the wires are spaced close enough to each other to 'see' overlapping populations of neurons, but wide enough so that the exact waveform of the signal recorded would be different on each of the wires.
		These differences would then be used to distinguish the contributions of different neurons based on the shape of their spikes (the extracellular correlates of their action potential) by spike sorting.
	en.wikipedia.org /wiki/Tetrode (409 words)

	Neuronal mechanisms of the anoxia-induced network oscillations in the rat hippocampus in vitro -- Dzhala et al. 536 ...
		A multiple unit activity in extracellular field recordings was phase locked to the negative and ascending phases of ANOs.
		Whole-cell and extracellular field recordings were performed in the CA3 area in the middle part of hippocampus except for the study of the longitudinal propagation.
		The transition to the second phase is manifested by a rapid neuronal depolarisation and a negative deflection in the extracellular field recordings.
	jp.physoc.org /cgi/content/full/536/2/521 (5435 words)

	Depth Recording of Averaged Evoked Potential of Olfactory Bulb (Site not responding. Last check: 2007-11-04)
		The analysis further demonstrated that the subsequent field of potential (phase III in their terminology) was compatible not with the geometry of the mitral cell pool, but with that of the granule cell population.
		The fields described experimentally were planar dipoles restricted to the lateral wall of the bulb with their axes normal to the bulbar surface.
		The spatial structure of the field was that of an asymmetric planar dipole with the zero isopotential surface located in or near the mitral cell layer.
	sulcus.berkeley.edu /FreemanWWW/manuscripts/IIIA4/72.html (7492 words)

	Extracellular field potential Definition / Extracellular field potential Research (Site not responding. Last check: 2007-11-04)
		Electrophysiological studies electrophysiologyElectrophysiology is the science and branch of physiology that pertains to the flow of ions in biological tissues and, in particular, to the electrical recording techniques that enable the measurement of this flow.
		lumps of nervous or muscular tissue, will produce signals commonly named local field potentials (LFP) that can be recorded with suitable equipment at the body surface as, e.g., electroencephalogramElectroencephalography is the neurophysiologic exploration of the electrical activity of the brain by the application of electrodes to the scalp.
		extracellular field potential is the electrical potential produced by cells, eg nerve or muscle cells, outside of the cell.
	www.elresearch.com /Extracellular_field_potential (457 words)

	Quantal Potential Fields around Individual Active Zones of Amphibian Motor-Nerve Terminals -- Bennett et al. 78 (3): ...
		of the equations for the quantal potential field in cylindrical
		is concluded that quantal potential fields at the neuromuscular
		In all cases, potentials and currents are shown at points no closer than 1 µm to the source; at closer distances the calculated values are not physically meaningful because of the singularity at the source point (see Appendix).
	www.biophysj.org /cgi/content/full/78/3/1106 (6768 words)

	Hippocampal brain slice electrophysiology - in vitro (Site not responding. Last check: 2007-11-04)
		Extracellular field potential was recorded from a population of IMHV neurons through a differential amplifier (AC-coupled and filtered at 10 Hz - 3 kHz, gain x1000; DAM-50, WPI).
		To obtain evoked extracellular synaptic responses in the CA1 region, Schaffer collateral&endash;comissural fibers were stimulated with electrical pulses at a frequency of 0.033 Hz and 100 µs duration, with several intensities (0&endash;20 V).
		Afferent fiber volleys and field excitatory postsynaptic potentials (EPSPs) were recorded from the stratum radiatum of the CA1 region using a glass micropipette.
	www.adinstruments.com /research/rapps/brain_slice.html (1179 words)

	Functional GABAergic Synaptic Connection in Neonatal Mouse Barrel Cortex -- Agmon et al. 16 (15): 4684 -- Journal of ...
		Field potentials were recorded at a gain of 1000× and filtered between 0.1 Hz and 5 KHz.
		Extracellular stimuli, at the intensity determined previously when recording the field potential, were delivered with interstimulus intervals of 20-300 sec, and synaptic currents were recorded at several different holding potentials.
		Extracellular field potential responses were recorded simultaneously with the current responses.
	www.jneurosci.org /cgi/content/full/16/15/4684 (7076 words)

	British Journal of Pharmacology - Potent depression of stimulus evoked field potential responses in the medial ... (Site not responding. Last check: 2007-11-04)
		Effects of serotonin on stimulus-induced field potentials in the superficial EC Stimulation in the lateral entorhinal cortex resulted in complex field potential responses in the superficial layers II and III of the medial entorhinal cortex.
		These potentials are composed of anti- and orthodromic components reflecting the efferent and afferent circuitry of the superficial EC (Figure 1).
		An altered paired pulse ratio of complex field potential responses might not be exclusively indicative for a presynaptic mechanism, since the different components of a complex shaped field potential show different paired pulse characteristics (Clark et al., 1994).
	www.nature.com /bjp/journal/v128/n1/full/0702788a.html (3942 words)

	Effects of Cerebral Ischemia on N-Methyl-D-Aspartate and Dihydropyridine-Sensitive Calcium Currents : An ...
		or pneumatic ejection, and extracellular field potential and
		Depression of the evoked activity by ischemia was expressed as percent decrease in the peak amplitude of hippocampal field potential evoked by fimbrial/commissural stimulation.
		Elevation of the extracellular concentrations of glutamate and aspartate in rat hippocampus during transient cerebral ischemia monitored by intracerebral microdialysis.
	stroke.ahajournals.org /cgi/content/full/27/1/127 (4041 words)

	Modeling Field potential using Genesis neural simulator: Complexity of potential behavior (Site not responding. Last check: 2007-11-04)
		Using GENESIS, a powerfull and versatile modular object oriented general neural simulator [1], we have implemented a field potential model and examined the effect of different network topologies on the simulated extracellular signal.
		Under the assumption that the extracellular environment has properties of a homogenous and noncapacitative conductor, the extracellularly measured field potential can be described analytically as a function of intensities and locations of a finite number of discrete current sources.
		We have written an additional extended object which represents the extracellular space and calculates continuously the field potential at the given recording site.
	www.lf2.cuni.cz /physiolres/feps/wittner.htm (229 words)

	British Journal of Pharmacology - Abstract of article: Potent depression of stimulus evoked field potential responses ... (Site not responding. Last check: 2007-11-04)
		The potentials are composed of an early antidromic and a late orthodromic component reflecting the efferent and afferent circuitry.
		Depression of field potential responses by serotonin was associated with a significant increase in paired-pulse facilitation from 1.15 to 1.88.
		The effects of serotonin on field potential responses were mimicked by 5-HT -receptor agonists (8-OH-DPAT, 5-CT) and partially prevented by the 5-HT -receptor antagonist (S-UH-301).
	www.nature.com /bjp/journal/v128/n1/abs/0702788a.html (387 words)

	Transition from Interictal to Ictal Activity in Limbic Networks In Vitro -- Dzhala and Staley 23 (21): 7873 -- Journal ...
		Extracellular field potential recording (wide band, 0.1 Hz to 4 kHz) at the CA3 pyramidal cell layer before filtering (left trace) and after filtering (right traces) for EEG components of IED (1-100 Hz bandpass filter) and IED-related fast field ripple (200-500 Hz bandpass filter).
		B, Simultaneous extracellular field potential records in the pyramidal cell layer of the CA3a, CA3b, CA3c, CA1, and granular cell layer (G. C.) of the dentate gyrus regions.
		Examples of simultaneous extracellular records from the CA3a and CA3c pyramidal cell layer represent consecutive interictal epileptiform discharges from the steady-state interictal (A), primary IED and secondary afterdischarges from the pre-ictal (B), and ictal-sustained discharges from the ictal (C) states.
	www.jneurosci.org /cgi/content/full/23/21/7873 (5567 words)

	Modulation of Burst Frequency, Duration, and Amplitude in the Zero-Ca2+ Model of Epileptiform Activity -- Bikson et al. ...
		Fields were generated across individual slices by passing current between 2 parallel AgCl-coated silver wires.
		Slices were always aligned such that the dendritic-somatic axis was parallel to the direction of the field (dotted lines) with bias as indicated in the diagram.
		The potential at electrode 2 was subtracted from electrode 1 to eliminate the applied field artifact.
	jn.physiology.org /cgi/content/full/82/5/2262 (4971 words)

	Anxiety Drugs, Anxiety Disorders in Children and Adolescents, Anxiety Drug side effects Buspar, Buspirone
		In fact, it can be concluded that the waveform of the extracellular signals differ from the one of the intracellular, which is related in part to the fact that the depolarization wave in the living tissues is not static.
		Equation [1.1] indicates that the extracellular potential would repeat the waveshape of the intracellular one only if the cell is considered isolated from the outside world.
		If the waveform of the extracellular signals was found to be close to the waveform of the first derivative of a typical intracellular signal, the waveform of these bipolar signals can be estimated with the second derivative of the intracellular signal.
	www.usahealthstore.com /stomach.html (2544 words)

	Cortical Spreading Depression and Migraine -- Neurotransmitter.net
		It is shown that propranolol, sumatriptan, methysergide, paracetamol and acetylsalicyclic acid decrease the propagation velocity of retinal spreading depression waves, accelerate the recovery of the optical and electrical signal and reduce the amplitude of the negative potential shift, concomitant with the spreading depression.
		SB-220453 (1, 3 and 10 mg/kg i.p.) produced a dose-related inhibition of this activity and at the highest dose tested, the median duration of changes in extracellular field potential and NO release were reduced to 4 min (25-75% range, 4-5 min) and 5 min (25-75% range, 5-5 min), respectively.
		SD is accompanied by a slow negative extracellular voltage and ion movements that are greatest in the inner plexiform layer of the retina.
	www.neurotransmitter.net /migrainecsd.html (17511 words)

	Choas in the CNS Paper - sec3 (Site not responding. Last check: 2007-11-04)
		When the extracellular field potential is properly recorded, it provides a basis to estimate the strength of the local mean field activity in the neighborhood of the neuronal population from the amplitude of its EEG.
		Other methods currently under development include measurement of cortical electric fields with voltage-sensitive dyes and optical recorders, (T'so et al., 1990) or with magnetic sensors to measure the magnetic components of the fields of dendritic current (Williamson and Kaufmann, 1989; Llinas et al., 1991).
		At present their instrumental noise levels are so high that they cannot be used without time ensemble averaging or narrow band pass filtering, so the use of these methods is restricted to measuring time ensemble averaged evoked potentials and not the unaveraged traces.
	sulcus.berkeley.edu /FLM/MS/WJF_man1.text/WJF_man1.sec3.html (1208 words)

	Multimodal characterization of population responses evoked by applied electric field in vitro: extracellular potential, ...
		Multimodal characterization of population responses evoked by applied electric field in vitro: extracellular potential, magnetic evoked field, transmembrane potential, and current-source density analysis -- Lopez et al.
		Multimodal characterization of population responses evoked by applied electric field in vitro: extracellular potential, magnetic evoked field, transmembrane potential, and current-source density analysis
		potentials occurring at the proximal pole of the Purkinje cell dendrites
	www.jneurosci.org /cgi/content/abstract/11/7/1998 (372 words)

	Nanotechnology Is BIG at NIST
		As the nation’s premier measurement laboratory, NIST is a key contributor to the National Nanotechnology Initiative (NNI), a long-term federal effort to speed the advance of the emerging fields of nanoscale science, engineering, and technology.
		Because collagen has several structural forms, a standardized reference is needed to ensure that results of studies using the extracellular matrix protein—a kind of scaffolding that supports cell growth and development—can be compared.
		The field of tissue engineering promises to repair functionality destroyed by injury, disease, and aging.
	www.nist.gov /nano (5679 words)

	Donoghue Lab (Site not responding. Last check: 2007-11-04)
		), the time course of extracellular field potential is proportional to the rate of change (first derivative) of the transmembrane potential, or
		Slower events would cause a steady extracellular potential, thus this relation would not be true.
		The fact that extracellular field potential has a time course approximately equal to transmembrane current allows us to use our recording to estimate current flow.
	donoghue.neuro.brown.edu /ec5.php (127 words)

	Publications
		Harman et al, "Numerical Computation of the External Potential Field of the Isolated Active Purkinge Strand in a Volume Conductor," 1973.
		Harman et al, "A Comparison of Two Methods of Determining the Extracellular Potential Field of an Isolated Purkinge Strand in a Volume Conductor," IEEE Transactions, Biomedical Engineering, Vol.
		Clark, E. Greco and T. Harman, "Experience with a Fourier Method for Determining the Extracellular Potential Fields of Excitable Cells with Cylindrical Geometry," Critical Reviews in Bioengineering, CRC Press, Inc., 1978.
	nas.cl.uh.edu /harman/paperpub.htm (873 words)

	Activation of the Cannabinoid Receptor Type 1 Decreases Glutamatergic and GABAergic Synaptic Transmission in the ...
		The effects of CB1 activation on the activity of a population of neurons in the LA were investigated by extracellular recording
		Long-term potentiation and paired-pulse facilitation in the hippocampal CA1 region.
		Modulation of synaptic transmission and long-term potentiation: Effects on paired pulse facilitation and EPSC variance in the CA1 region of the hippocampus.
	www.learnmem.org /cgi/content/full/10/2/116 (5693 words)

	Representation of cochlea within primary auditory cortex in the cat
		Frequency receptive fields typically are determined using extracellular recordings of spike discharge in response to pure tone stimuli.
		However, the narrow receptive fields thus derived may be misleading, and underestimate the spectral breadth of inputs to cortical neurons, as evidenced by a number of studies.
		Cortical microinjection of the GABAA receptor agonist muscimol reduced the bandwidth of LFP-based receptive fields in layer 4, indicating that intracortical pathways contribute to broad receptive fields.
	www.cns.nyu.edu /events/earclub/artfiles/Kaur2004.doc (8098 words)

	APStracts 9:0087J, 2002. (Site not responding. Last check: 2007-11-04)
		To investigate the temperature sensitivity of low-Ca2+ induced nonsynaptic and low- Mg2+ induced synaptic ictogenesis under submerged and interface conditions, we compared changes of extracellular field potential and extracellular potassium concentration at room temperature (23 ± 1 °C) and at 35 ± 1 °C in hippocampal- entorhinal cortex slices.
		To investigate the different temperature effects under submerged and interface conditions, measurements of extra- and intracellular pH and extracellular space volume were performed.
		The reduced extracellular space volume under interface conditions may lead to an enlarged ephaptic transmission and therefore promotes low-Mg2+ and low-Ca2+ induced spontaneous epileptiform activity.
	www.uth.tmc.edu /apstracts/2002/jn/May/87j.html (350 words)

	Granular Cell Integration in the Mormyromast System (Site not responding. Last check: 2007-11-04)
		Although this single EPSP is not sufficient to generate an action potential in the postsynaptic granular cell, it creates a time-window within which appropriately timed afferent inputs are enhanced so that they are more likely to elicit a spike in the post-synaptic granular cell (Bell and Grant, 1992; figures III-2a, III-2b).
		The refractory period (time window following an action potential during which the neuron cannot generate another spike) in the fine central terminals of these mormyromast afferents, whose narrow axonal branches limit speed of recovery to resting potential, is large enough to allow only the first spike of an afferent burst to be relayed.
		The function of LMI inhibition is thought to be similar to lateral inhibition in the mammalian retina; an object with high conductance near one area of the skin will suppress firing in granular cells representing more distal adjacent areas of the skin.
	www.ohsu.edu /nsi/faculty/robertpa/lab/vickers02/thesis/text/granIntegration.htm (571 words)

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