Repetitive firing in layer V neurons from cat neocortex in vitro

1984 ◽  
Vol 52 (2) ◽  
pp. 264-277 ◽  
Author(s):  
C. E. Stafstrom ◽  
P. C. Schwindt ◽  
W. E. Crill
Keyword(s):  
Firing Rate ◽  
Interspike Interval ◽  
Rate Of Change ◽  
Repetitive Firing ◽  
Linear Segment ◽  
Interspike Intervals ◽  
Firing Rates ◽  
Wide Range ◽  
Layer V

Input-output relations of large neurons from layer V of cat sensorimotor cortex were studied in an in vitro slice preparation using steps and ramps of intracellularly injected current. Depolarization attained during the interspike interval (ISI) was compared to the voltage levels required to activate a previously described (29) persistent sodium current (INaP). INaP was studied using a single-electrode voltage clamp in the same cells tested for firing behavior. Following an injected current step, firing rate declined smoothly to a steady level with a time course that was approximately exponential in most cells (tau, 9-43 ms). In most cells, the relation between firing rate and injected current (f-I relation) consisted of two linear segments, both for adapted, steady firing and for early intervals during adaptation. The slope of the steeper, initial (or sole) linear segment of the f-I curve averaged 26.2 Hz/nA during steady firing and was steeper when plotted for early interspike intervals. The variation of the depolarization at which spike initiation occurred (firing level) and the membrane potential between rhythmic spikes was examined during adaptation and steady firing. In most cells, firing level rose rapidly during a rhythmic train to a steady value. The steady firing level attained remained unchanged over a wide range of steady firing rates. Nevertheless, the mean depolarization during the interspike interval (V) increased approximately linearly with steady firing rate. Even at the slowest firing rates, V is sufficient to activate INaP. The use of injected current ramps demonstrated that neocortical cells were sensitive to rate of change of stimulus current (dI/dt) as well as its amplitude (I). The use of ramps followed by steady currents demonstrated that the repetitive response lagged behind changes in stimulus parameters and did not reach a steady state even during slow ramps; i.e., the response depended on time as well as on I and dI/dt. Instantaneous firing rate during the ramp increased linearly with time for a wide range of ramp slopes (dI/dt). The instantaneous firing rate of early interspike intervals was also linearly related to ramp slope for small ramp slopes. In spite of these linear relationships, quantitative analysis indicated that firing rate during ramp stimulation cannot, in general, be described by a simple linear combination of separate amplitude- and rate-dependent terms. The repetitive firing properties of the in vitro neurons are compared to those of in vivo neocortical neurons and other cell types.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Predicting the response of striatal spiny neurons to sinusoidal input

2017 ◽  
Vol 118 (2) ◽  
pp. 855-873 ◽  
Author(s):  
Charles. J. Wilson
Keyword(s):  
Firing Rate ◽  
Action Potentials ◽  
Interspike Interval ◽  
Spike Timing ◽  
Repetitive Firing ◽  
Phase Resetting ◽  
Spiny Neurons ◽  
Wide Range ◽  
Sinusoidal Input ◽  
Sinusoidal Currents

During repetitive firing, the timing of action potentials is determined by the interaction between the input and voltage-sensitive currents throughout the interspike interval. This interaction is encapsulated in the neuron’s phase-resetting curve. The phase-resetting curve predicted spike timing to small sinusoidal currents over a wide range of stimulus frequencies. Firing patterns were most sensitive to oscillatory components near the cell’s own firing rate, even in the presence of noise and other inputs.

Serotonin has different effects on two classes of Betz cells from the cat

1994 ◽  
Vol 72 (4) ◽  
pp. 1925-1937 ◽  
Author(s):  
W. J. Spain
Keyword(s):  
Firing Rate ◽  
Potassium Conductance ◽  
Membrane Conductance ◽  
Constant Current ◽  
Repetitive Firing ◽  
Calcium Dependent ◽  
Constant Current Stimulation ◽  
Ionic Mechanisms ◽  
Betz Cells

1. Intracellular recording from cat Betz cells in vitro revealed a strong correlation between the dominant effect of serotonin (5-HT) and the Betz cell subtype in which it occurred. In large Betz cells that show posthyperpolarization excitation (termed PHE cells), 5-HT evoked a long-lasting membrane depolarization, whereas 5-HT evoked an initial hyperpolarization of variable duration in smaller Betz cells that show posthyperpolorization inhibition (termed PHI cells). 2. Voltage-clamp studies revealed that 5-HT caused a depolarizing shift of activation of the cation current Ih, which resulted in the depolarization in PHE cells, whereas the hyperpolarization in PHI cells is caused by an increase in a resting potassium conductance. 3. The effect of 5-HT on firing properties during constant current stimulation also differed consistently in the two types of Betz cells. In PHE cells the initial firing rate increased after 5-HT application, but the steady firing was unaffected. The depolarizing shift of Ih activation caused the increase of initial firing rate. 4. In PHI cells 5-HT caused a decrease in spike frequency adaptation. The decrease in adaptation was caused by a combination of two conductance changes. First, 5-HT caused a slow afterdepolarization in PHI cells that could trigger repetitive firing in the absence of further stimulation. The sADP depended on calcium entry through voltage-gated channels and was associated with a decrease in membrane conductance. Second, 5-HT caused reduction of a slow calcium-dependent potassium current that normally contributes to slow adaptation. 5. In conclusion, the effect of 5-HT on excitability differs systematically in Betz cell subtypes in part because they have different dominant ionic mechanisms that are modulated. If we assume that PHE cells and PHI cells represent fast and slow pyramidal tract (PT) neurons respectively, 5-HT will cause early recruitment of fast PT cells and delay recruitment of slow PT cells during low levels of synaptic excitation.

Possible Effects of Depolarizing GABAA Conductance on the Neuronal Input–Output Relationship: A Modeling Study

2005 ◽  
Vol 93 (6) ◽  
pp. 3504-3523 ◽  
Author(s):  
Kenji Morita ◽  
Kunichika Tsumoto ◽  
Kazuyuki Aihara
Keyword(s):  
Firing Rate ◽  
Cortical Neurons ◽  
Reversal Potential ◽  
Pyramidal Cells ◽  
Resting Potential ◽  
Input Output ◽  
Wide Range ◽  
The Relationship

Recent in vitro experiments revealed that the GABAA reversal potential is about 10 mV higher than the resting potential in mature mammalian neocortical pyramidal cells; thus GABAergic inputs could have facilitatory, rather than inhibitory, effects on action potential generation under certain conditions. However, how the relationship between excitatory input conductances and the output firing rate is modulated by such depolarizing GABAergic inputs under in vivo circumstances has not yet been understood. We examine herewith the input–output relationship in a simple conductance-based model of cortical neurons with the depolarized GABAA reversal potential, and show that a tonic depolarizing GABAergic conductance up to a certain amount does not change the relationship between a tonic glutamatergic driving conductance and the output firing rate, whereas a higher GABAergic conductance prevents spike generation. When the tonic glutamatergic and GABAergic conductances are replaced by in vivo–like highly fluctuating inputs, on the other hand, the effect of depolarizing GABAergic inputs on the input–output relationship critically depends on the degree of coincidence between glutamatergic input events and GABAergic ones. Although a wide range of depolarizing GABAergic inputs hardly changes the firing rate of a neuron driven by noncoincident glutamatergic inputs, a certain range of these inputs considerably decreases the firing rate if a large number of driving glutamatergic inputs are coincident with them. These results raise the possibility that the depolarized GABAA reversal potential is not a paradoxical mystery, but is instead a sophisticated device for discriminative firing rate modulation.

In vitro diencephalic neuronal thermosensitivity in normotensive and hypertensive rats

1989 ◽  
Vol 256 (2) ◽  
pp. R560-R566
Author(s):  
K. A. Travis ◽  
J. A. Boulant
Keyword(s):  
Firing Rate ◽  
Spontaneous Activity ◽  
Tissue Temperature ◽  
Tissue Slices ◽  
Spontaneously Hypertensive ◽  
Dorsomedial Hypothalamus ◽  
Firing Rates ◽  
Wistar Kyoto ◽  
Morphological Differences

Because morphological differences exist in hypothalamic neurons from spontaneously hypertensive (SH) and normotensive Wistar-Kyoto (WKY) rats, the present study recorded neuronal spontaneous activity and thermosensitivity from diencephalic tissue slices of these two strains. With the use of extracellular recordings from horizontal tissue slices, neurons were characterized according to location, firing rate at 37 degrees C, and firing rate response to changes in local tissue temperature. Compared with WKY neurons, SH neurons had higher firing rates in the preoptic-anterior hypothalamus and lower firing rates in the dorsomedial hypothalamus. In addition, SH warm-sensitive neurons were less thermosensitive over the hyperthermic range (37-40 degrees C), and SH temperature-insensitive neurons had higher spontaneous firing rates. These differences in spontaneous activity and thermosensitivity provide a neuronal basis to explain the elevation of core temperature observed in SH rats.

Electrophysiological properties and synaptic responses in the deep layers of the human epileptogenic neocortex in vitro

1989 ◽  
Vol 61 (3) ◽  
pp. 589-606 ◽  
Author(s):  
M. Avoli ◽  
A. Olivier
Keyword(s):  
Epileptiform Activity ◽  
Equilibrium Potential ◽  
Repetitive Firing ◽  
Inward Rectification ◽  
Resting Membrane Potential ◽  
Linear Segment ◽  
Electrophysiological Properties ◽  
Deep Layers ◽  
Synaptic Responses

1. Neocortical slices of the first and second temporal gyrus and frontal lobe, removed in human epileptic patients for the relief of intractable seizures, were maintained in vitro at 35 +/- 1 degrees C. Electrophysiological properties of neurons in the deep layers (1,800–2,600 micron below the pial surface) were studied with conventional intracellular recording and stimulation techniques. Synaptic responses were evoked by extracellular focal stimuli. Intracellular injections of some cells with the fluorescent dye Lucifer yellow revealed large spiny pyramidal neurons. 2. Values of input resistance, resting membrane potential (Vm), and action-potential amplitude were similar for neurons in different cortical regions. These parameters were also similar when neurons were grouped in accordance to the degree of electrographic epileptiform activity displayed by the cortical tissue in situ. 3. Inward rectification occurred when neurons were depolarized by 5–15 mV positive to the resting Vm. This rectification was abolished by extracellular application of tetrodotoxin (TTX, 1 microM), but was still observed in the presence of the Ca2+-channel blocker Cd2+ (2 mM). Pulses of hyperpolarizing current elicited a slowly developing inward rectification, called anomalous rectification, which was insensitive to TTX, but blocked by extracellular application of Cs+ (1-2 mM). 4. Intracellular injection of depolarizing square pulses of current (0.1-4 s) evoked repetitive firing. In most cells the firing rate decreased smoothly for tens of milliseconds (i.e., it adapted) before reaching a steady level. Plots of the relation between frequency of the repetitive firing and injected current (f-I curve) displayed two linear segments for the early intervals as well as for the adapted and/or the steady firing. The slope of the initial, steeper linear segment of the f-I curve computed during the early intervals and during the adapted firing was 163 +/- 51 and 56 +/- 27 (SD) Hz/nA, respectively. 5. A long-lasting (up to 8 s) afterhyperpolarization (AHP) followed the repetitive firing induced by square pulses of depolarizing current. Its amplitude was directly proportional to the amount of current injected, it was sensitive to changes in the Vm, and it had an equilibrium potential 10–40 mV negative to the resting Vm. This value plus the fact that the AHP could be recorded with KCl-filled microelectrodes suggested that it was caused by an increase in conductance to K+ ions. Bath application of the Ca2+ channel blockers Cd2+ (2 mM) or Mn2+ (2 mM) decreased and eventually blocked the AHP.(ABSTRACT TRUNCATED AT 400 WORDS)

Jaw muscle afferent firing during an isotonic jaw-positioning task in the monkey

1983 ◽  
Vol 50 (1) ◽  
pp. 61-73 ◽  
Author(s):  
C. R. Larson ◽  
D. V. Finocchio ◽  
A. Smith ◽  
E. S. Luschei
Keyword(s):  
Firing Rate ◽  
Interspike Interval ◽  
Movement Velocity ◽  
Firing Rates ◽  
Actual Increase ◽  
Position Sensitivity ◽  
Jaw Muscle ◽  
Muscle Afferent ◽  
Position Sensitive ◽  
Jaw Position

The activity of jaw muscle receptors was studied by recording neurons in the mesencephalic nucleus of the trigeminal nerve in monkeys trained to control the position and movement of their mandible. Jaw position was measured by a weighted lever resting on the mandibular incisors. The force required to maintain the position of the lever was varied; in most cases it was either 25 or 360 g. Firing rates of neurons were related to stationary mandibular positions and to the velocity of movements during intervals when the movement velocity was constant. Of 49 neurons studied in detail, 21 fired at rates that were consistently and linearly related to static incisal openings. This static position sensitivity was typically about 5 spikes/mm of incisal opening. Most position-sensitive neurons fired at higher rates during opening movements and at lower rates during closing movements than would be accounted for by their position sensitivity. This sensitivity to the velocity of movement was not linear, however; slow closing movements sometimes did not produce a decrease in firing rate, and an actual increase during muscle shortening was seen in a few instances. The position sensitivity of eight neurons was evaluated during different loading conditions; in no case did it change substantially. Of the remaining 28 neurons, 26 fired at high rates during all opening movements and either stopped firing or fired at low, sporadic rates during closing movements. The static position sensitivity of these neurons was weak and variable both within and between neurons. The velocity sensitivity of these stretch-sensitive neurons was very nonlinear. Except for a range of slow movements (+/- 5 mm/s), the firing rate was maximal (200 spikes/s or higher) for most opening movements and zero for most closing movements. Maximal firing rates were higher when the loads being moved were increased from 25 to 360 g. The majority of position-sensitive neurons exhibited a large interspike-interval variability at wide incisal opening. In most of these neurons, this interspike-interval variability was periodic, usually at a rate of about 10 periods/s, and took the form of "saw-tooth" modulation on a record of instantaneous firing rate. Neurons that exhibited this modulation in a very prominent form also exhibited, in many instances, a substantial increase in firing rate during closing jaw movements.

scholarly journals Ion channel degeneracy enables robust and tunable neuronal firing rates

2015 ◽  
Vol 112 (38) ◽  
pp. E5361-E5370 ◽  
Author(s):  
Guillaume Drion ◽  
Timothy O’Leary ◽  
Eve Marder
Keyword(s):  
Ion Channel ◽  
Firing Rate ◽  
Ionic Currents ◽  
Neuronal Firing ◽  
Neuron Models ◽  
Firing Rates ◽  
Wide Range ◽  
Current Curve ◽  
Important Means ◽  
High Firing

Firing rate is an important means of encoding information in the nervous system. To reliably encode a wide range of signals, neurons need to achieve a broad range of firing frequencies and to move smoothly between low and high firing rates. This can be achieved with specific ionic currents, such as A-type potassium currents, which can linearize the frequency-input current curve. By applying recently developed mathematical tools to a number of biophysical neuron models, we show how currents that are classically thought to permit low firing rates can paradoxically cause a jump to a high minimum firing rate when expressed at higher levels. Consequently, achieving and maintaining a low firing rate is surprisingly difficult and fragile in a biological context. This difficulty can be overcome via interactions between multiple currents, implying a need for ion channel degeneracy in the tuning of neuronal properties.

Response to CO2 of neurons in the rostral ventral medulla in vitro

1995 ◽  
Vol 73 (3) ◽  
pp. 933-944 ◽  
Author(s):  
G. B. Richerson
Keyword(s):  
Membrane Potential ◽  
Patch Clamp ◽  
Firing Rate ◽  
Respiratory Acidosis ◽  
Repetitive Firing ◽  
Spontaneous Firing ◽  
Whole Cell ◽  
Bath Solution ◽  
Co2 Sensitivity

1. It has been hypothesized that CO2-sensitive neurons are located in the rostral ventral medulla. To demonstrate this at the cellular level, perforated patch-clamp recordings were made from rat medullary slices in vitro. The effect of respiratory acidosis/alkalosis on the electrophysiologic properties of neurons was studied by recording membrane potential while changing the CO2 of the bath solution and allowing pH to vary. 2. At baseline, most neurons in the rostral ventrolateral medulla (VLM) and rostral medullary raphe spontaneously fired repetitively at a regular rate (3.3 +/- 2.5 Hz, mean +/- SD) with a linear interspike ramp depolarization (n = 102 of 135). Spontaneous firing continued after synaptic blockade with high-magnesium, low-calcium solution (n = 14 of 15). Spontaneous firing of calcium spikes continued in tetrodotoxin (TTX; n = 13 of 13), but was blocked by TTX and cadmium (n = 4 of 4). 3. The effect of respiratory acidosis/alkalosis on neurons was examined by changing the CO2 of the bicarbonate-buffered bath solution within the range of 3-9%. Most neurons studied (n = 74 of 105) did not change their firing rate in response to this stimulus; however, some neurons were stimulated (n = 16) and other neurons were inhibited (n = 15) by increases in CO2. 4. In many CO2-stimulated neurons, the increase in firing rate caused by an increase in CO2 was associated with an increase in slope of the linear interspike ramp depolarization, whereas in many CO2-inhibited neurons the opposite occurred, i.e., an increase in CO2 resulted in a decrease in slope of the ramp depolarization. These changes occurred without a change in the level of afterhyperpolarization or spike threshold. 5. Whole cell patch-clamp recording invariably resulted in loss of spontaneous and stimulated repetitive firing over 10-40 min despite good resting potential, input resistance, and amplitude of single depolarization-evoked spikes. CO2 produced no change in membrane potential in neurons after rundown of repetitive firing. The loss of repetitive firing and CO2 sensitivity with whole cell recording required the use of perforated-patch recordings of membrane potential or cell-attached-patch recordings of spike transients to accurately study the baseline electrophysiologic properties and CO2 sensitivity of rostral medullary neurons. 6. Neuronal location was determined before each recording using direct visualization of living slices, and after some recordings using biocytin staining. CO2-stimulated and CO2-inhibited neurons were both found to have cell bodies in the rostral VLM, an area thought to contain central respiratory chemoreceptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Slow conductances in neurons from cat sensorimotor cortex in vitro and their role in slow excitability changes

1988 ◽  
Vol 59 (2) ◽  
pp. 450-467 ◽  
Author(s):  
P. C. Schwindt ◽  
W. J. Spain ◽  
R. C. Foehring ◽  
M. C. Chubb ◽  
W. E. Crill
Keyword(s):  
Voltage Clamp ◽  
Sensorimotor Cortex ◽  
Time Course ◽  
Divalent Cations ◽  
Ionic Currents ◽  
Repetitive Firing ◽  
Layer V ◽  
K Concentration

1. The electrophysiological and pharmacological properties of slow afterpotentials in large layer V neurons from cat sensorimotor cortex were studied in an in vitro slice preparation using intracellular recording and single-microelectrode voltage clamp. These properties were used to assess the role of afterpotential mechanisms in prolonged excitability changes. 2. The mean duration of a slow afterhyperpolarization (sAHP) was 13.5 s following 100 spikes evoked at 100 Hz. Its time course was best described by two exponential components, which decayed with time constants of several hundred milliseconds (the early sAHP) and several seconds (the late sAHP). The amplitude of both the early and late components were sensitive to membrane potential and raised extracellular K+ concentration [( K+]o). 3. The early sAHP was reduced when divalent cations were substituted for Ca2+, whereas the late sAHP was unaffected. We conclude that a Ca2+-mediated K+ conductance is responsible for much of the early sAHP. In the presence of tetrodotoxin (TTX), 1-s voltage-clamp steps were used to evoke slow AHPs or outward ionic currents. These AHPs and currents were abolished in Ca2+-free perfusate, but they had a maximum duration of only a few seconds. Thus the slowest outward currents we could observe during voltage clamp in TTX were responsible only for the early sAHP. 4. The possible role of an electrogenic Na+-K+ pump in the late sAHP was examined by applying ouabain to the slice. Ouabain did not reduce selectively the late sAHP, and its effect was best explained by a decrease in intracellular K+ concentration and an increase in [K+]o. 5. Muscarinic and beta-adrenergic agonists reduced or abolished the entire (early and late) sAHP. Neither type of agonist affected the Ca2+-dependent, apamin-sensitive medium-duration afterhyperpolarization (35). We conclude that both the Ca2+-mediated K+ conductance underlying the early sAHP and the Ca2+-independent mechanisms underlying the late sAHP are sensitive to at least two classes of transmitter agonists. 6. We focused on the muscarinic effects. When concentrations greater than 5 microM were employed, the entire (early and late) sAHP was replaced by a slow afterdepolarization (sADP). Muscarine reduced the sAHP directly by reducing the underlying outward ionic currents and indirectly by causing the sADP. The sADP was Ca2+-mediated, since it was abolished by Ca2+-free perfusate but not by TTX. 7. The ionic currents underlying the sAHP and the sADP influenced excitability for seconds following evoked repetitive firing.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals On Firing Rate Estimation for Dependent Interspike Intervals

2015 ◽  
Vol 27 (3) ◽  
pp. 699-724 ◽  
Author(s):  
Elisa Benedetto ◽  
Federico Polito ◽  
Laura Sacerdote
Keyword(s):  
Firing Rate ◽  
Conditional Distribution ◽  
Compartment Model ◽  
Nonparametric Estimator ◽  
Interspike Intervals ◽  
Instantaneous Rate ◽  
Two Compartment Model ◽  
Consistency Properties

If interspike intervals are dependent, the instantaneous firing rate does not catch important features of spike trains. In this case, the conditional instantaneous rate plays the role of the instantaneous firing rate for the case of samples of independent interspike intervals. If the conditional distribution of the interspikes intervals (ISIs) is unknown, it becomes difficult to evaluate the conditional firing rate. We propose a nonparametric estimator for the conditional instantaneous firing rate for Markov, stationary, and ergodic ISIs. An algorithm to check the reliability of the proposed estimator is introduced, and its consistency properties are proved. The method is applied to data obtained from a stochastic two-compartment model and to in vitro experimental data.

Sign in / Sign up

Export Citation Format

Share Document