scholarly journals Dipolar extracellular potentials generated by axonal projections

2017 ◽  
Author(s):  
Thomas McColgan ◽  
Ji Liu ◽  
Paula T Kuokkanen ◽  
Catherine E Carr ◽  
Hermann Wagner ◽  
...  
Keyword(s):  
Action Potentials ◽  
Brain Regions ◽  
Auditory Brainstem ◽  
Multielectrode Array ◽  
Field Potentials ◽  
Physiological Basis ◽  
Nucleus Laminaris ◽  
Axonal Projections ◽  
Terminal Zone ◽  
Source Of Information

AbstractExtracellular field potentials (EFPs) are an important source of information in neuroscience, but their physiological basis is in many cases still a matter of debate. Axonal sources are typically discounted in modeling and data analysis because their contributions are assumed to be negligible. Here, we show experimentally and theoretically that contributions of axons to EFPs can be significant. Modeling action potentials propagating along axons, we showed that EFPs were prominent in the presence of a terminal zone where axons branch and terminate in close succession, as found in many brain regions. Our models predicted a dipolar far field and a polarity reversal at the center of the terminal zone. We confirmed these predictions using EFPs from the barn owl auditory brainstem where we recorded in nucleus laminaris using a multielectrode array. These results demonstrate that axonal terminal zones produce EFPs with considerable amplitude and spatial reach.

scholarly journals Dipolar extracellular potentials generated by axonal projections

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Thomas McColgan ◽  
Ji Liu ◽  
Paula Tuulia Kuokkanen ◽  
Catherine Emily Carr ◽  
Hermann Wagner ◽  
...  
Keyword(s):  
Action Potentials ◽  
Brain Regions ◽  
Auditory Brainstem ◽  
Multielectrode Array ◽  
Field Potentials ◽  
Physiological Basis ◽  
Nucleus Laminaris ◽  
Axonal Projections ◽  
Terminal Zone ◽  
Source Of Information

Extracellular field potentials (EFPs) are an important source of information in neuroscience, but their physiological basis is in many cases still a matter of debate. Axonal sources are typically discounted in modeling and data analysis because their contributions are assumed to be negligible. Here, we established experimentally and theoretically that contributions of axons to EFPs can be significant. Modeling action potentials propagating along axons, we showed that EFPs were prominent in the presence of terminal zones where axons branch and terminate in close succession, as found in many brain regions. Our models predicted a dipolar far field and a polarity reversal at the center of the terminal zone. We confirmed these predictions using EFPs from the barn owl auditory brainstem where we recorded in nucleus laminaris using a multielectrode array. These results demonstrate that axonal terminal zones can produce EFPs with considerable amplitude and spatial reach.

scholarly journals Auditory Brainstem Response Wave III is Correlated with Extracellular Field Potentials from Nucleus Laminaris of the Barn Owl

2018 ◽  
Vol 104 (5) ◽  
pp. 874-877
Author(s):  
Paula T. Kuokkanen ◽  
Anna Kraemer ◽  
Richard Kempter ◽  
Christine Köppl ◽  
Catherine E. Carr
Keyword(s):  
Auditory Brainstem Response ◽  
Barn Owl ◽  
Auditory Brainstem ◽  
Field Potentials ◽  
Nucleus Laminaris ◽  
Brainstem Response

Epileptiform activity induced by low chloride medium in the CA1 subfield of the hippocampal slice

1990 ◽  
Vol 64 (6) ◽  
pp. 1747-1757 ◽  
Author(s):  
M. Avoli ◽  
C. Drapeau ◽  
P. Perreault ◽  
J. Louvel ◽  
R. Pumain
Keyword(s):  
Membrane Potential ◽  
Large Amplitude ◽  
Action Potentials ◽  
Hippocampal Slice ◽  
Epileptiform Activity ◽  
Field Potential ◽  
Pyramidal Cells ◽  
Input Resistance ◽  
Field Potentials ◽  
Maximal Amplitude

1. Extracellular and intracellular recordings and measurements of the extracellular concentration of free K+ ([K+]o) were performed in the CA1 subfield of the rat hippocampal slice during perfusion with artificial cerebrospinal fluid (ACSF) in which NaCl had been replaced with equimolar Na-isethionate or Na-methylsulfate (hereafter called low Cl- ACSF). 2. CAl pyramidal cells perfused with low Cl- ACSF generated intracellular epileptiform potentials in response to orthodromic, single-shock stimuli delivered in stratum (S.) radiatum. Low-intensity stimuli evoked a short-lasting epileptiform burst (SB) of action potentials that lasted 40–150 ms and was followed by a prolonged hyperpolarization. When the stimulus strength was increased, a long-lasting epileptiform burst (LB) appeared; it had a duration of 4–15 s and consisted of an early discharge of action potentials similar to the SB, followed by a prolonged, large-amplitude depolarizing plateau. The refractory period of the LB was longer than 20 s. SB and LB were also seen after stimulation of the alveus. 3. Variations of the membrane potential with injection of steady. DC current modified the shape of SB and LB. When microelectrodes filled with the lidocaine derivative QX-314 were used, the amplitudes of both SB and LB increased in a linear fashion during changes of the baseline membrane potential in the hyperpolarizing direction. The membrane input resistance, as measured by injecting brief square pulses of hyperpolarizing current, decreased by 65-80% during the long-lasting depolarizing plateau of LB. 4. A synchronous field potential and a transient increase in [K+]o accompanied the epileptiform responses. The extracellular counterpart of the SB was a burst of three to six population spikes and a small increase in [K+]o (less than or equal to 2 mM from a resting value of approximately 2.5 mM). The LB was associated with a large-amplitude, biphasic, negative field potential and a large increase in [K+]o (up to 12.4 mM above the resting value). Changes in [K+]o during the LB were largest at the border between S. oriens and S. pyramidale. This was also the site where the field potentials measured 2–5 s after the stimulus attained their maximal amplitude. Conversely, field potentials associated with the early component of the LB or with the SB displayed a maximal amplitude in the S. radiatum. 5. Spontaneous SBs and LBs were at times recorded in the CA1 and in the CA3 subfield.(ABSTRACT TRUNCATED AT 400 WORDS)

Synaptic and intrinsic responses of medical entorhinal cortical cells in normal and magnesium-free medium in vitro

1988 ◽  
Vol 59 (5) ◽  
pp. 1476-1496 ◽  
Author(s):  
R. S. Jones ◽  
U. Heinemann
Keyword(s):  
Entorhinal Cortex ◽  
Action Potentials ◽  
Membrane Conductance ◽  
Nmda Receptor Antagonist ◽  
Field Potentials ◽  
Cortical Cells ◽  
Medial Entorhinal Cortex ◽  
Membrane Hyperpolarization

1. Extracellular recordings were made from slices of hippocampus plus parahippocampal regions maintained in vitro. Field potentials, recorded in the entorhinal cortex after stimulation in the subiculum, resembled those observed in vivo. 2. Washout of magnesium from the slices resulted in paroxysmal events which resembled those occurring during sustained seizures in vivo. These events were greatest in amplitude and duration in layers IV/V of the medial entorhinal cortex and could occur both spontaneously and in response to subicular stimulation. Spontaneous seizure-like events were not prevented by severing the connections between the hippocampus and entorhinal cortex, but much smaller and shorter events occurring in the dentate gyrus were stopped by this manipulation. Both spontaneous and evoked paroxysmal events were blocked by perfusion with the N-methyl-D-aspartate (NMDA) receptor antagonist, DL-2-amino-5-phosphonovalerate (2-AP5). 3. Neurons in layers IV/V were characterized by intracellular recording. Injection of depolarizing current in most cells evoked a train of nondecrementing action potentials with only weak spike frequency accommodation and little or no posttrain after hyperpolarization. 4. A small number of cells displayed burst response when depolarized by positive current. The burst consisted of a slow depolarization with superimposed action potentials which decreased in amplitude and increased in duration during the discharge. The burst was terminated by a strong after hyperpolarization and thereafter, during prolonged current pulses a train of nondecrementing spikes occurred. The burst response remained if the cell was held at hyperpolarized levels but was inactivated by holding the cell at a depolarized level. 5. Depolarizing synaptic potentials could be evoked by stimulation in the subiculum. A delayed and prolonged depolarization clearly decremented with membrane hyperpolarization and, occasionally, increased with depolarization. 6. Washout of magnesium from the slices resulted in an enhancement of the late depolarization and a reversal of its voltage dependence. Eventually a single shock to the subiculum evoked a large all-or-none paroxysmal depolarization associated with a massive increase in membrane conductance. Similar events occurred spontaneously in all cells tested. The paroxysmal depolarizations, both spontaneous and evoked, were rapidly blocked by 2-AP5. 7. It is concluded that medial entorhinal cortical cells possess several intrinsic and synaptic properties which confer an extreme susceptibility to generation of sustained seizure activity.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Connections of the auditory brainstem in a Songbird,Taeniopygia guttata.I. Projections of nucleus angularis and nucleus laminaris to the auditory torus

2010 ◽  
Vol 518 (11) ◽  
pp. 2109-2134 ◽  
Author(s):  
Nils O.E. Krützfeldt ◽  
Priscilla Logerot ◽  
M. Fabiana Kubke ◽  
J. Martin Wild
Keyword(s):  
Auditory Brainstem ◽  
Nucleus Laminaris ◽  
Nucleus Angularis

The Physiological Basis of Executive Function and Working Memory

1996 ◽  
Vol 2 (6) ◽  
pp. 345-352 ◽  
Author(s):  
Mark D'Esposito ◽  
Murray Grossman
Keyword(s):  
Working Memory ◽  
Executive Function ◽  
Cognitive Abilities ◽  
Brain Regions ◽  
Cognitive Domain ◽  
Distributed Network ◽  
Cortical Function ◽  
Physiological Basis ◽  
Appropriate Behavior ◽  
Prefrontal Cortical

The term “executive function” has been used to capture the highest order of cognitive abilities, including the planning, flexibility, organization and regulation necessary for the execution of an appropriate behavior. Executive function, although an elusive cognitive domain, may be highly dependent on working memory, which refers to the temporary storage and manipulation of information. The physiology of working memory is beginning to be mapped in both monkey and human studies at the neuroanatomical and neurochemical levels. Working memory is likely subserved by a distributed network of brain regions in which the prefrontal cortex is critical, subserving the process of maintaining representations across time. There is also a relationship between dopaminergic projections in the brain and working memory. Improved understanding of the physiological basis of executive functioning and working memory will provide a narrower view of prefrontal cortical function and may lead to new therapies in patients with cognitive dysfunction.

scholarly journals In-phase and in-antiphase connectivity in EEG

2021 ◽  
Author(s):  
Christian O'Reilly ◽  
John D Lewis ◽  
Rebecca J Theilmann ◽  
Mayada Elsabbagh ◽  
Jeanne Townsend
Keyword(s):  
Functional Connectivity ◽  
Local Field ◽  
Significant Proportion ◽  
Brain Regions ◽  
Field Potentials ◽  
Volume Conduction ◽  
Confounding Effect ◽  
Neuronal Communication ◽  
Neural Communication ◽  
Eeg Connectivity

Zero-lag synchrony is generally discarded from functional connectivity studies to eliminate the confounding effect of volume conduction. Demonstrating genuine and significant unlagged synchronization between distant brain regions would indicate that most electroencephalography (EEG) connectivity studies neglect an important mechanism for neuronal communication. We previously demonstrated that local field potentials recorded intracranially tend to synchronize with no lag between homotopic brain regions. This synchrony occurs most frequently in antiphase, potentially supporting corpus callosal inhibition and interhemispheric rivalry. We are now extending our investigation to EEG. By comparing the coherency in a recorded and a surrogate dataset, we confirm the presence of a significant proportion of genuine zero-lag synchrony unlikely to be due to volume conduction or to recording reference artifacts. These results stress the necessity for integrating zero-lag synchrony in our understanding of neural communication and for disentangling volume conduction and zero-lag synchrony when estimating EEG sources and their functional connectivity.

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