Electrophysiology of globus pallidus neurons in vitro

1994 ◽  
Vol 72 (3) ◽  
pp. 1127-1139 ◽  
Author(s):  
A. Nambu ◽  
R. Llinas
Keyword(s):  
Globus Pallidus ◽  
Input Resistance ◽  
Repetitive Firing ◽  
Type I ◽  
Type Ii ◽  
Low Threshold ◽  
Membrane Oscillations ◽  
Neuronal Type ◽  
A Current ◽  
Membrane Level

1. We investigated the electrical properties of globus pallidus neurons intracellularly using brain slices from adult guinea pigs. Three types of neurons were identified according to their intrinsic electrophysiological properties. 2. Type I neurons (59%) were silent at the resting membrane level (-65 +/- 10 mV, mean +/- SD) and generated a burst of spikes, with strong accommodation, to depolarizing current injection. Calcium-dependent low-frequency (1-8 Hz) membrane oscillations were often elicited by membrane depolarization (-53 +/- 8 mV). A low-threshold calcium conductance and an A-current were also identified. The mean input resistance of this neuronal type was 70 +/- 22 M omega. 3. Type II neurons (37%) fired spontaneously at the resting membrane level (-59 +/- 9 mV). Their repetitive firing (< or = 200 Hz) was very sensitive to the amplitude of injected current and showed weak accommodation. Sodium-dependent high-frequency (20-100 Hz) subthreshold membrane oscillations were often elicited by membrane depolarization. This neuronal type demonstrated a low-threshold calcium spike and had the highest input resistance (134 +/- 62 M omega) of the three neuron types. 4. Type III neurons (4%) did not fire spontaneously at the resting membrane level (-73 +/- 5 mV). Their action potentials were characterized by a long duration (2.3 +/- 0.6 ms). Repetitive firing elicited by depolarizing current injection showed weak or no accommodation. This neuronal type had an A-current and showed the lowest input resistance (52 +/- 35 M omega) of the three neuron types. 5. Stimulation of the caudoputamen evoked inhibitory postsynaptic potentials (IPSPs) in Type I and II neurons. In Type II neurons the IPSPs were usually followed by rebound firing. Excitatory postsynaptic potentials and antidromic responses were also elicited in some Type I and II neurons. The estimated conduction velocity of the striopallidal projection was < 1 m/s (Type I neurons, 0.49 +/- 0.37 m/s; Type II neurons, 0.33 +/- 0.13 m/s).

The Roles Potassium Currents Play in Regulating the Electrical Activity of Ventral Cochlear Nucleus Neurons

2003 ◽  
Vol 89 (6) ◽  
pp. 3097-3113 ◽  
Author(s):  
Jason S. Rothman ◽  
Paul B. Manis
Keyword(s):  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
Threshold Current ◽  
Repetitive Firing ◽  
Resting Membrane Potential ◽  
Type I ◽  
Type Ii Cells ◽  
Type Ii ◽  
Ventral Cochlear Nucleus ◽  
Discharge Patterns

Using kinetic data from three different K+ currents in acutely isolated neurons, a single electrical compartment representing the soma of a ventral cochlear nucleus (VCN) neuron was created. The K+ currents include a fast transient current ( IA), a slow-inactivating low-threshold current ( ILT), and a noninactivating high-threshold current ( IHT). The model also includes a fast-inactivating Na+ current, a hyperpolarization-activated cation current ( Ih), and 1–50 auditory nerve synapses. With this model, the role IA, ILT, and IHT play in shaping the discharge patterns of VCN cells is explored. Simulation results indicate that IHT mainly functions to repolarize the membrane during an action potential, and IA functions to modulate the rate of repetitive firing. ILT is found to be responsible for the phasic discharge pattern observed in Type II cells (bushy cells). However, by adjusting the strength of ILT, both phasic and regular discharge patterns are observed, demonstrating that a critical level of ILT is necessary to produce the Type II response. Simulated Type II cells have a significantly faster membrane time constant in comparison to Type I cells (stellate cells) and are therefore better suited to preserve temporal information in their auditory nerve inputs by acting as precise coincidence detectors and having a short refractory period. Finally, we demonstrate that modulation of Ih, which changes the resting membrane potential, is a more effective means of modulating the activation level of ILT than simply modulating ILT itself. This result may explain why ILT and Ih are often coexpressed throughout the nervous system.

In vitro characterization of neurons in the ventral part of the nucleus tractus solitarius. I. Identification of neuronal types and repetitive firing properties

1987 ◽  
Vol 58 (1) ◽  
pp. 195-214 ◽  
Author(s):  
M. S. Dekin ◽  
P. A. Getting ◽  
S. M. Johnson
Keyword(s):  
High Frequency ◽  
Nucleus Tractus Solitarius ◽  
State Level ◽  
Repetitive Firing ◽  
Type I ◽  
Type Ii ◽  
Steady State Level ◽  
Shaped Cell ◽  
Firing Properties

1. An in vitro brain stem slice preparation from adult guinea pigs was used to determine the properties of neurons located in the ventral part of the nucleus tractus solitarius (NTS), an area associated with the dorsal respiratory group. Based upon their morphology and their repetitive firing properties, three classes of ventral NTS neurons, termed types I, II, and III, were observed. 2. Type I neurons were multipolar with pyramidal-shaped cell bodies. These neurons responded to prolonged depolarizations from a resting level of -50 mV with a discrete, high-frequency burst of spikes, which rapidly adapted to a low steady-state level. When depolarized from levels more negative than -65 mV, the initial burst was diminished. 3. Type II neurons were multipolar with fusiform-shaped cell bodies. Type II neurons responded to depolarizations from -50 mV with an initial high spike frequency, which gradually adapted to a steady-state level. When depolarized from levels more negative than -60 mV, these neurons displayed a delay between the onset of the stimulus and the first spike. This delay has been termed “delayed excitation.” The expression of delayed excitation was modulated by both the size and duration of hyperpolarizing prepulses that preceded depolarization. 4. Type III neurons were multipolar with spherical shaped-cell bodies. In response to depolarizations from -50 mV, these neurons displayed high-frequency firing with little adaptation. The repetitive firing properties of type III neurons were not modulated by hyperpolarization. 5. Bulbospinal neurons in the ventral NTS were identified using retrograde transport of rhodamine-labeled latex beads injected into the region of the phrenic motor nucleus at spinal cord levels C4 through C6. Only type I and type II neurons were labeled in the ventral NTS (0.2-1.0 mm rostral to the obex). Both contralateral and ipsilateral projections were observed. Contralaterally, type I and II neurons were evenly distributed. Ipsilaterally, however, type II neurons accounted for two-thirds of the labeled neurons. 6. Type I and II neurons had similar input resistances and time constants: 97.0 +/- 17.6 M omega and 14.4 +/- 2.2 ms (n = 5) for type I and 107.0 +/- 11.2 M omega and 13.7 +/- 1.6 ms for type II (n = 5).(ABSTRACT TRUNCATED AT 400 WORDS)

Electrical filtering in gerbil isolated type I semicircular canal hair cells

1996 ◽  
Vol 75 (5) ◽  
pp. 2117-2123 ◽  
Author(s):  
K. J. Rennie ◽  
A. J. Ricci ◽  
M. J. Correia
Keyword(s):  
Membrane Potential ◽  
Hair Cells ◽  
Semicircular Canal ◽  
Input Resistance ◽  
Constant Current ◽  
Type I ◽  
Type Ii ◽  
Peak Voltage ◽  
Type I Cells ◽  
I Cells

1. Membrane potential responses of dissociated gerbil type I semicircular canal hair cells to current injections in whole cell current-clamp have been measured. The input resistance of type I cells was 21.4 +/- 14.3 (SD) M omega, (n = 25). Around the zero-current potential (Vz = -66.6 +/- 9.3 mV, n = 25), pulsed current injections (from approximately -200 to 750 pA) produced only small-amplitude, pulse-like changes in membrane potential. 2. Injecting constant current to hyperpolarize the membrane to around -100 mV resulted in a approximately 10-fold increase in membrane resistance. Current pulses superimposed on this constant hyperpolarization produced larger and more complex membrane potential changes. Depolarizing currents > or = 200 pA caused a rapid transient peak voltage before a plateau. 3. Membrane voltage was able to faithfully follow sine-wave current injections around Vz over the range 1-1,000 Hz with < 25% attenuation at 1 kHz. A previously described K conductance, IKI, which is active at Vz, produces the low input resistance and frequency response. This was confirmed by pharmacologically blocking IKI. This conductance, present in type I cells but not type II hair cells, would appear to confer on type I cells a lower gain, but a much broader bandwidth at Vz, than seen in type II cells.

scholarly journals Respiratory motoneuron properties during the transition from gill to lung breathing in the American bullfrog

2019 ◽  
Vol 316 (3) ◽  
pp. R281-R297 ◽  
Author(s):  
Tara A. Janes ◽  
Stéphanie Fournier ◽  
Simon Chamberland ◽  
Gregory D. Funk ◽  
Richard Kinkead
Keyword(s):  
Action Potential ◽  
Input Resistance ◽  
Type I ◽  
Type Ii ◽  
Excitatory Postsynaptic Currents ◽  
Synaptic Inputs ◽  
Postsynaptic Currents ◽  
American Bullfrog ◽  
Action Potential Threshold ◽  
Potential Threshold

Amphibian respiratory development involves a dramatic metamorphic transition from gill to lung breathing and coordination of distinct motor outputs. To determine whether the emergence of adult respiratory motor patterns was associated with similarly dramatic changes in motoneuron (MN) properties, we characterized the intrinsic electrical properties of American bullfrog trigeminal MNs innervating respiratory muscles comprising the buccal pump. In premetamorphic tadpoles (TK stages IX–XVIII) and adult frogs, morphometric analyses and whole cell recordings were performed in trigeminal MNs identified by fluorescent retrograde labeling. Based on the amplitude of the depolarizing sag induced by hyperpolarizing voltage steps, two MN subtypes (I and II) were identified in tadpoles and adults. Compared with type II MNs, type I MNs had larger sag amplitudes (suggesting a larger hyperpolarization-activated inward current), greater input resistance, lower rheobase, hyperpolarized action potential threshold, steeper frequency-current relationships, and fast firing rates and received fewer excitatory postsynaptic currents. Postmetamorphosis, type I MNs exhibited similar sag, enhanced postinhibitory rebound, and increased action potential amplitude with a smaller-magnitude fast afterhyperpolarization. Compared with tadpoles, type II MNs from frogs received higher-frequency, larger-amplitude excitatory postsynaptic currents. Input resistance decreased and rheobase increased postmetamorphosis in all MNs, concurrent with increased soma area and hyperpolarized action potential threshold. We suggest that type I MNs are likely recruited in response to smaller, buccal-related synaptic inputs as well as larger lung-related inputs, whereas type II MNs are likely recruited in response to stronger synaptic inputs associated with larger buccal breaths, lung breaths, or nonrespiratory behaviors involving powerful muscle contractions.

Groupings of nonpyramidal and pyramidal cells with specific physiological and morphological characteristics in rat frontal cortex

1993 ◽  
Vol 69 (2) ◽  
pp. 416-431 ◽  
Author(s):  
Y. Kawaguchi
Keyword(s):  
Nmda Receptor ◽  
Frontal Cortex ◽  
Morphological Characteristics ◽  
Pyramidal Cells ◽  
Input Resistance ◽  
Morphological Properties ◽  
Repetitive Firing ◽  
Current Pulses ◽  
Low Threshold ◽  
Layer V

1. Physiological and morphological properties of layer V non-pyramidal and pyramidal cells in isolated slices of frontal cortex from young rats (16-22 days postnatal) were studied by whole-cell, current-clamp recording of visualized cell bodies coupled with intracellular staining by biocytin at 26-27 degrees C. 2. Plotting of spike width at half amplitude against input resistance revealed two physiological categories of nonpyramidal cells. One class (n = 29) had input resistances lower than 400 M omega and spike widths at half amplitude shorter than 0.8 ms; the other (n = 22) had input resistances higher than 400 M omega and spike widths longer than 0.8 ms. According to their spike firing characteristics, the former are called fast-spiking (FS) cells, and the latter low-threshold spike (LTS) cells. 3. Resting potentials were more negative in FS cells than in LTS cells. Membrane time constants in LTS cells were four times larger than those of FS cells. Afterhyperpolarizations (AHPs) following action potentials consisted of a single component in FS cells, but two components with early and late peaks were observed in LTS cells. AHPs of FS cells had faster time-to-peak and larger amplitude than the early component of the AHPs of LTS cells. 4. Low-threshold spikes induced by depolarizing current pulses were observed at hyperpolarized potentials in LTS cells, but not in FS cells. The low-threshold spikes in LTS cells could be activated at hyperpolarized potentials by synaptic potentials. 5. Spike trains elicited by depolarizing current pulses in FS cells showed almost no spike-frequency adaptation, whereas those in LTS cells showed adaptation. 6. Excitatory postsynaptic potentials (EPSPs) of both groups of nonpyramidal cells contained N-methyl-D-aspartate (NMDA) receptor-mediated components. A combination of stimulation-induced EPSPs with depolarization caused repetitive firing in FS cells that was abolished by NMDA receptor blockers. Repetitive firing was not observed in LTS cells under these conditions. 7. The somal size of the two classes of nonpyramidal cells was similar. FS cells were all multipolar in shape, whereas LTS cells included both multipolar and bitufted types. The dendrites of some FS cells extended up into layers II/III, but there were also other FS cells with their dendrites restricted in layer V. Dendrites of LTS cells were mostly restricted to layer V. Dendrites of FS cells were mostly smooth, but those of LTS cells possessed a modest but consistent population of spines.(ABSTRACT TRUNCATED AT 400 WORDS)

Two Types of Neurons in the Rat Cerebellar Nuclei as Distinguished by Membrane Potentials and Intracellular Fillings

2001 ◽  
Vol 85 (5) ◽  
pp. 2017-2029 ◽  
Author(s):  
Uwe Czubayko ◽  
Fahad Sultan ◽  
Peter Thier ◽  
Cornelius Schwarz
Keyword(s):  
Firing Rate ◽  
Cerebellar Nuclei ◽  
Membrane Potentials ◽  
Burst Firing ◽  
Type I ◽  
Type Ii ◽  
Intrinsic Properties ◽  
Plateau Potentials ◽  
Lower Amplitude ◽  
Low Threshold

Classically, three classes of neurons in the cerebellar nuclei (CN), defined by different projection targets and content of transmitters, have been distinguished. However, evidence for different types of neurons based on different intrinsic properties is lacking. The present study reports two types of neurons defined mainly by their intrinsic properties, as determined by whole-cell patch recordings. The majority of cells (type I, n = 63) showed cyclic burst firing whereas a small subset (type II, n = 7) did not. Burst firing was used to distinguish the two types of neurons because, as it turned out, pharmacological interference could not be used to convert the non-bursting cells to bursting ones. Some of the membrane potentials exclusively present in type I neurons, such as sodium and calcium plateau potentials, low-threshold calcium spikes, and a slow calcium-dependent afterhyperpolarization, were found to contribute to the generation of burst firing. Other membrane potentials of type I neurons were not obviously related to the generation of bursts. These were 1) the lower amplitude and width of the action potential during spontaneous activity, 2) a sequence of afterhyperpolarization–afterdepolarization–afterhyperpolarization following each spike, and 3) the high spontaneous firing rate. In contrast, type II neurons lacked slow plateau potentials and low threshold spikes. Their action potentials showed higher amplitude and width and were followed by a single deep afterhyperpolarization. Furthermore, they showed a lower firing rate at rest. In both types of neurons, a delayed inward rectification was present. Neurons filled with neurobiotin revealed that the sizes of the somata and dendritic fields of type I neurons comprised the whole range known from Golgi studies, whereas those of the few type II neurons recovered were found to be in the lowest range. In view of their size and scarcity, we propose that type II neurons may correspond to CN interneurons.

Inward rectification and its effects on the repetitive firing properties of bulbospinal neurons located in the ventral part of the nucleus tractus solitarius

1993 ◽  
Vol 70 (2) ◽  
pp. 590-601 ◽  
Author(s):  
M. S. Dekin
Keyword(s):  
Membrane Potential ◽  
Nucleus Tractus Solitarius ◽  
Reversal Potential ◽  
Repetitive Firing ◽  
Inward Rectification ◽  
Motor Nucleus ◽  
Type I ◽  
Type Ii ◽  
Membrane Hyperpolarization ◽  
Negative Current

1. An in vitro brain stem slice from adult guinea pigs was used to study the effects of membrane hyperpolarization in two classes of bulbospinal neurons, called types I and II, from the ventral parts of the nucleus tractus solitarius (vNTS). These bulbospinal neurons project to the phrenic motor nucleus and make up the dorsal respiratory group, a sensorimotor integrating area for rhythmic breathing movements. 2. Negative current injections (1 s long) were used in the discontinuous current-clamp mode to study the input resistance (Rin) in both classes of bulbospinal vNTS neurons. The mean Rin for type I neurons was 88.7 +/- 13.8 (SD) M omega (n = 19) and for type II neurons was 92.6 +/- 14.0 M omega (n = 16). Both classes of neurons displayed a depolarizing sag and inward rectification during negative current injections to membrane-potential levels less than or equal to -70 mV. The magnitude of the depolarizing sag became larger as the size of the negative current step was increased. On release from hyperpolarization, both cell types also exhibited a large anode break hyperpolarization (ABH). 3. The ABH was abolished in the presence of 5 mM 4-amino-pyridine (4-AP), whereas the depolarizing sag and inward rectification were not affected. In the place of the ABH, a small postinhibitory rebound (PIR) depolarization was observed on release from hyperpolarization. The magnitude of PIR was dependent on the size of the depolarizing sag. In the presence of both 5 mM 4-AP and 5 mM Cs+, the depolarizing sag and PIR were completely blocked, whereas Rin was increased. 4. The ionic currents underlying the ABH and depolarizing sag were directly observed by the use of the discontinuous single-electrode voltage-clamp technique. The ABH was caused by activation of an A-current (IKA). The depolarizing sag was associated with a hyperpolarization-activated inward current (IH), which was activated at membrane-potential levels less than or equal to -70 mV. The peak amplitude of IH in type I neurons was -335 +/- 16 pA (n = 13) and in type II cells was -327 +/- 14 pA (n = 11). 5. IH currents did not display inactivation during the hyperpolarizing voltage step. The IH current became larger when [K+]o was increased from 4 mM (control) to 12 mM and was blocked in the presence of 5 mM Cs+. The estimated reversal potential for the IH current was -41.5 +/- 4.8 mV (n = 8).(ABSTRACT TRUNCATED AT 400 WORDS)

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