scholarly journals Spike-Frequency Adaptation and Intrinsic Properties of an Identified, Looming-Sensitive Neuron

2006 ◽  
Vol 96 (6) ◽  
pp. 2951-2962 ◽  
Author(s):  
Fabrizio Gabbiani ◽  
Holger G. Krapp
Keyword(s):  
Time Course ◽  
Input Resistance ◽  
Spike Frequency ◽  
Membrane Properties ◽  
Inward Rectification ◽  
Movement Detector ◽  
Spike Frequency Adaptation ◽  
Current Pulses ◽  
Frequency Adaptation

We investigated in vivo the characteristics of spike-frequency adaptation and the intrinsic membrane properties of an identified, looming-sensitive interneuron of the locust optic lobe, the lobula giant movement detector (LGMD). The LGMD had an input resistance of 4–5 MΩ, a membrane time constant of about 8 ms, and exhibited inward rectification and rebound spiking after hyperpolarizing current pulses. Responses to depolarizing current pulses revealed the neuron's intrinsic bursting properties and pronounced spike-frequency adaptation. The characteristics of adaptation, including its time course, the attenuation of the firing rate, the mutual dependency of these two variables, and their dependency on injected current, closely followed the predictions of a model first proposed to describe the adaptation of cat visual cortex pyramidal neurons in vivo. Our results thus validate the model in an entirely different context and suggest that it might be applicable to a wide variety of neurons across species. Spike-frequency adaptation is likely to play an important role in tuning the LGMD and in shaping the variability of its responses to visual looming stimuli.

Spike frequency adaptation studied in hypoglossal motoneurons of the rat

1995 ◽  
Vol 73 (5) ◽  
pp. 1799-1810 ◽  
Author(s):  
A. Sawczuk ◽  
R. K. Powers ◽  
M. D. Binder
Keyword(s):  
Steady State ◽  
Time Course ◽  
Firing Frequency ◽  
Spike Frequency ◽  
Membrane Properties ◽  
Repetitive Firing ◽  
Hypoglossal Nucleus ◽  
Spike Frequency Adaptation ◽  
Frequency Adaptation ◽  
Three Phases

1. We studied spike frequency adaptation of motoneuron discharge in the rat hypoglossal nucleus using a brain stem slice preparation. The characteristics of adaptation in response to long (60 s) injected current steps were qualitatively similar to those observed previously in cat hindlimb motoneurons. The discharge rate typically exhibited a rapid initial decline, characterized by a linear frequency-time relation, followed by a gradual exponential decline that continued for the duration of current injection. However, a more systematic, quantitative analysis of the data revealed that there were often three distinct phases of the adaptation rather than two. 2. The three phases of adaptation (initial, early, and late) were present in at least one 60-s trial of repetitive firing in all but a small number of motoneurons. Initial adaptation was limited to the first few spikes except in a few trials (7%) in which there was no initial adaptation. The time course of the subsequent decline in rate could be adequately described by a single-exponential function in about half of the trials (48%). In the remaining trials this subsequent decline in frequency was better described as the sum of two exponential functions: an early phase, lasting < 2 s, and a late phase, which lasted for the duration of the discharge period. 3. The magnitude of initial adaptation was correlated with the initial firing frequency (i.e., the reciprocal of the 1st interspike interval). The magnitudes of the early and late phases of adaptation were correlated with the firing frequency reached at the end of initial adaptation. Neither the magnitudes nor the time courses of the three phases were correlated with other membrane properties such as input resistance, rheobase, or repetitive firing threshold. 4. The slope of the frequency-current (f-I) curve was steeper in the initial phase (first 2-5 spikes) than in either the early (< 2 s) or late (> 2 s) phases of adaptation as previously reported by other investigators. In the absence of early adaptation, a steady state for the f-I slope was reached by 0.7-1 s, the time typically reported in studies of repetitive discharge. However, when early adaptation was present (50% of the trials), a steady-state value for the f-I slope was not reached until the cell had discharged for > 1 s. 5. To characterize the time course of firing rate recovery from the adaptive processes, the current was turned off for periods of < or = 10 s during the course of a 60-s trial.(ABSTRACT TRUNCATED AT 400 WORDS)

Encoder Adaptation Modulates the Visual Responses of Crayfish Interneurons

2004 ◽  
Vol 92 (1) ◽  
pp. 327-340 ◽  
Author(s):  
Raymon M. Glantz ◽  
John P. Schroeter
Keyword(s):  
Firing Rate ◽  
Time Course ◽  
Light Flash ◽  
Time Derivative ◽  
Input Resistance ◽  
Spike Frequency ◽  
Visual Response ◽  
Spike Frequency Adaptation ◽  
Visual Responses ◽  
Frequency Adaptation

The responses of sustaining and dimming fibers were characterized by the time varying firing rates elicited by extrinsic current and flashes of light. These data were simulated by an adaptive integrate-and-fire model. A postimpulse shunt conductance simulated spike-frequency adaptation. The correlation between observed and model current-elicited impulse rates was 0.94–0.98. However, except for a difference in input resistance (both measured and simulated), the voltage to impulse encoders of the two cell groups was similar and exhibited comparable degrees of spike-frequency adaptation (40 to 45%). The encoder model derived from current-elicited responses (with fixed parameters) was used to simulate visual responses elicited by light flashes. These simulations included a synaptic current derived from the time course of the postsynaptic potential (PSP). The sustaining fiber visual response consisted of a large excitatory PSP and high-frequency transient burst that adapted (by ∼80%) to a low-frequency plateau discharge. The simulations indicated that spike-frequency adaptation had no effect on the transient discharge but reduced the plateau firing rate by ∼60%. Encoder adaptation enhances the sustaining fiber response to the time derivative of the stimulus. In dimming fibers, the light flash elicits an inhibitory PSP that interrupts the “dark discharge” and an off response following the end of the flash. The simulations indicated that spike-frequency adaptation reduces the firing rate of both the dark discharge and the off response. Thus the model suggests that different effects of encoder adaptation on the two cell types arise from the same encoder mechanisms, but different actions are determined by differences in impulse rate and the time course of the discharge.

Slow Adaptation in Fast-Spiking Neurons of Visual Cortex

2005 ◽  
Vol 93 (2) ◽  
pp. 1111-1118 ◽  
Author(s):  
V. F. Descalzo ◽  
L. G. Nowak ◽  
J. C. Brumberg ◽  
D. A. McCormick ◽  
M. V. Sanchez-Vives
Keyword(s):  
Time Scale ◽  
Time Course ◽  
Firing Frequency ◽  
Spike Frequency ◽  
Spike Frequency Adaptation ◽  
Slow Time ◽  
Frequency Adaptation ◽  
Slow Adaptation ◽  
Fast Spiking

Fast-spiking (FS) neurons are a class of inhibitory interneurons classically characterized as having short-duration action potentials (<0.5 ms at half height) and displaying little to no spike-frequency adaptation during short (<500 ms) depolarizing current pulses. As a consequence, the resulting injected current intensity versus firing frequency relationship is typically steep, and they can achieve firing frequencies of ≤1 kHz. Here we have investigated the properties of FS neurons discharges on a longer time scale. Twenty second discharges were induced in electrophysiologically identified FS neurons by means of current injection either with sinusoidal current or with square pulses. We found that virtually all FS neurons recorded in cortical slices do show spike-frequency adaptation but with a slow time course (τ = 2–19 s). This slow time course has precluded the observation of this property in previous studies that used shorter pulses. Contrary to the classical view of FS neurons functional properties, long-duration discharges were followed by a slow afterhyperpolarization lasting ≤23 s. During this postadaptation period, the excitability of the neurons was decreased on average for 16.7 ± 6.8 s, therefore rendering the cell less responsive to subsequent afferent inputs. Slow adaptation is also reported here for FS neurons recorded in vivo. This longer time scale of adaptation in FS neurons may be critical for balancing excitation and inhibition as well as for the understanding of cortical network computations.

scholarly journals Selective attenuation of Ether-a-go-go related K+ currents by endogenous acetylcholine reduces spike-frequency adaptation and network correlation

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Edward D Cui ◽  
Ben W Strowbridge
Keyword(s):  
Late Phase ◽  
Pyramidal Cells ◽  
Spike Frequency ◽  
Spike Frequency Adaptation ◽  
Firing Rates ◽  
Frequency Adaptation ◽  
Rat Neocortex ◽  
Persistent Firing ◽  
K Current

Most neurons do not simply convert inputs into firing rates. Instead, moment-to-moment firing rates reflect interactions between synaptic inputs and intrinsic currents. Few studies investigated how intrinsic currents function together to modulate output discharges and which of the currents attenuated by synthetic cholinergic ligands are actually modulated by endogenous acetylcholine (ACh). In this study we optogenetically stimulated cholinergic fibers in rat neocortex and find that ACh enhances excitability by reducing Ether-à-go-go Related Gene (ERG) K+ current. We find ERG mediates the late phase of spike-frequency adaptation in pyramidal cells and is recruited later than both SK and M currents. Attenuation of ERG during coincident depolarization and ACh release leads to reduced late phase spike-frequency adaptation and persistent firing. In neuronal ensembles, attenuating ERG enhanced signal-to-noise ratios and reduced signal correlation, suggesting that these two hallmarks of cholinergic function in vivo may result from modulation of intrinsic properties.

scholarly journals Slow Spike Frequency Adaptation in Neurons of the Rat Subthalamic Nucleus

2009 ◽  
Vol 102 (6) ◽  
pp. 3689-3697 ◽  
Author(s):  
David Barraza ◽  
Hitoshi Kita ◽  
Charles J. Wilson
Keyword(s):  
Firing Rate ◽  
Subthalamic Nucleus ◽  
Similar Rate ◽  
Excitatory Input ◽  
Spike Frequency ◽  
Spike Frequency Adaptation ◽  
Frequency Adaptation ◽  
Long Duration ◽  
Subthalamic Neurons

Neurons of the subthalamic nucleus (STN) are very sensitive to applied currents, firing at 10–20/s during spontaneous activity, but increasing to peak firing rates of 200/s with applied currents <0.5 nA. They receive a powerful tonic excitatory input from neurons in the cerebral cortex, yet in vivo maintain an irregular firing rate only slightly higher than the autonomous firing rate seen in slices. Spike frequency adaptation acts to normalize background firing rate by removing slow trends in firing due to changes in average input. Subthalamic neurons have been previously described as showing little spike frequency adaptation, but this was based on tests using brief stimuli. We applied long-duration depolarizing current steps to STN neurons in slices and observed a very strong spike frequency adaptation with a time constant of 20 s and that recovered at a similar rate. This adaptation could return firing to near-baseline levels during prolonged current pulses that transiently drove the cells at high rates. The current responsible for adaptation was studied in voltage clamp during and after high-frequency driving of the cell and was determined to be a slowly accumulating K+ current. This current was independent of calcium or sodium entry and could be induced with long-duration voltage steps after blockade of action potentials. In addition to the adaptation current, driven firing produced slow inactivation of the persistent Na+ current, which also contributed to the reduced excitability of STN cells during and after driven firing.

Changes in Electrophysiological Properties of Lamprey Spinal Motoneurons During Fictive Swimming

2002 ◽  
Vol 88 (5) ◽  
pp. 2463-2476 ◽  
Author(s):  
Michelle M. Martin
Keyword(s):  
Spinal Cord ◽  
Input Resistance ◽  
Spike Frequency ◽  
Calcium Currents ◽  
Quiescent State ◽  
Spike Frequency Adaptation ◽  
Free Solution ◽  
Spinal Motoneurons ◽  
Electrophysiological Properties ◽  
Frequency Adaptation

Electrophysiological properties of lamprey spinal motoneurons were measured to determine whether their cellular properties change as the spinal cord goes from a quiescent state to the active state of fictive swimming. Intracellular microelectrode recordings of membrane potential were made from motoneurons in the isolated spinal cord preparation. Electrophysiological properties were first characterized in the quiescent spinal cord, and then fictive swimming was induced by perfusion with d-glutamate and the measurements were repeated. During the depolarizing excitatory phase of fictive swimming, the motoneurons had significantly reduced rheobase and significantly increased input resistance compared with the quiescent state, with no significant changes in these parameters during the repolarizing inhibitory phase of swimming. Spike threshold did not change significantly during fictive swimming compared with the quiescent state. During fictive swimming, the slope of the spike frequency versus injected current ( F-I) relationship decreased significantly as did spike-frequency adaptation and the amplitude of the slow after-spike hyperpolarization (sAHP). Serotonin is known to be released endogenously from the spinal cord during fictive swimming and is known to reduce the amplitude of the sAHP. Therefore the effects of serotonin on cellular properties were tested in the quiescent spinal cord. It was found that, in addition to reducing the sAHP amplitude, serotonin also reduced the slope of the F-I relationship and reduced spike-frequency adaptation, reproducing the changes observed in these parameters during fictive swimming. Application of spiperone, a serotonin antagonist, significantly increased the sAHP amplitude during fictive swimming but had no significant effect on F-I slope or adaptation. Because serotonin may act in part through reduction of calcium currents, the effect of calcium-free solution (cobalt substituted for calcium) was tested in the quiescent spinal cord. Similar to fictive swimming and serotonin application, the calcium-free solution significantly reduced the sAHP amplitude, the slope of the F-I relationship, and spike-frequency adaptation. These results suggest that there are significant changes in the firing properties of motoneurons during fictive swimming compared with the quiescent state, and it is possible that these changes may be attributed in part to the endogenous release of serotonin acting via reduction of calcium currents.

Electrophysiological Classes of Cat Primary Visual Cortical Neurons In Vivo as Revealed by Quantitative Analyses

2003 ◽  
Vol 89 (3) ◽  
pp. 1541-1566 ◽  
Author(s):  
Lionel G. Nowak ◽  
Rony Azouz ◽  
Maria V. Sanchez-Vives ◽  
Charles M. Gray ◽  
David A. McCormick
Keyword(s):  
Short Duration ◽  
Cortical Neurons ◽  
Action Potentials ◽  
Low Frequency ◽  
Pyramidal Cells ◽  
Spike Frequency ◽  
Spike Frequency Adaptation ◽  
Frequency Adaptation ◽  
Layer 4

To facilitate the characterization of cortical neuronal function, the responses of cells in cat area 17 to intracellular injection of current pulses were quantitatively analyzed. A variety of response variables were used to separate the cells into subtypes using cluster analysis. Four main classes of neurons could be clearly distinguished: regular spiking (RS), fast spiking (FS), intrinsic bursting (IB), and chattering (CH). Each of these contained significant subclasses. RS neurons were characterized by trains of action potentials that exhibited spike frequency adaptation. Morphologically, these cells were spiny stellate cells in layer 4 and pyramidal cells in layers 2, 3, 5, and 6. FS neurons had short-duration action potentials (<0.5 ms at half height), little or no spike frequency adaptation, and a steep relationship between injected current intensity and spike discharge frequency. Morphologically, these cells were sparsely spiny or aspiny nonpyramidal cells. IB neurons typically generated a low frequency (<425 Hz) burst of spikes at the beginning of a depolarizing current pulse followed by a tonic train of action potentials for the remainder of the pulse. These cells were observed in all cortical layers, but were most abundant in layer 5. Finally, CH neurons generated repetitive, high-frequency (350–700 Hz) bursts of short-duration (<0.55 ms) action potentials. Morphologically, these cells were layer 2–4 (mainly layer 3) pyramidal or spiny stellate neurons. These results indicate that firing properties do not form a continuum and that cortical neurons are members of distinct electrophysiological classes and subclasses.

scholarly journals Absence of Pannexin 1 Stabilizes Hippocampal Excitability After Intracerebral Treatment With Aβ (1-42) and Prevents LTP Deficits in Middle-Aged Mice

2021 ◽  
Vol 13 ◽  
Author(s):  
Nicolina Südkamp ◽  
Olena Shchyglo ◽  
Denise Manahan-Vaughan
Keyword(s):  
Neuronal Excitability ◽  
Long Term Potentiation ◽  
Firing Frequency ◽  
Spike Frequency ◽  
Synaptic Function ◽  
Membrane Properties ◽  
Neuronal Membrane ◽  
Spike Frequency Adaptation ◽  
Control Peptide ◽  
Frequency Adaptation

Beta-amyloid protein [Aβ(1-42)] plays an important role in the disease progress and pathophysiology of Alzheimer's disease (AD). Membrane properties and neuronal excitability are altered in the hippocampus of transgenic AD mouse models that overexpress amyloid precursor protein. Although gap junction hemichannels have been implicated in the early pathogenesis of AD, to what extent Pannexin channels contribute to Aβ(1-42)-mediated brain changes is not yet known. In this study we, therefore, investigated the involvement of Pannexin1 (Panx1) channels in Aβ-mediated changes of neuronal membrane properties and long-term potentiation (LTP) in an animal model of AD. We conducted whole-cell patch-clamp recordings in CA1 pyramidal neurons 1 week after intracerebroventricular treatments of adult wildtype (wt) and Panx1 knockout (Panx1-ko) mice with either oligomeric Aβ(1-42), or control peptide. Panx1-ko hippocampi treated with control peptide exhibited increased neuronal excitability compared to wt. In addition, action potential (AP) firing frequency was higher in control Panx1-ko slices compared to wt. Aβ-treatment reduced AP firing frequency in both cohorts. But in Aβ-treated wt mice, spike frequency adaptation was significantly enhanced, when compared to control wt and to Aβ-treated Panx1-ko mice. Assessment of hippocampal LTP revealed deficits in Aβ-treated wt compared to control wt. By contrast, Panx1-ko exhibited LTP that was equivalent to LTP in control ko hippocampi. Taken together, our data show that in the absence of Pannexin1, hippocampi are more resistant to the debilitating effects of oligomeric Aβ. Both Aβ-mediated impairments in spike frequency adaptation and in LTP that occur in wt animals, are ameliorated in Panx1-ko mice. These results suggest that Panx1 contributes to early changes in hippocampal neuronal and synaptic function that are triggered by oligomeric Aβ.

Contribution of Persistent Sodium Currents to Spike-Frequency Adaptation in Rat Hypoglossal Motoneurons

2005 ◽  
Vol 93 (2) ◽  
pp. 1035-1041 ◽  
Author(s):  
Jinsong Zeng ◽  
Randall K. Powers ◽  
Gregory Newkirk ◽  
Marc Yonkers ◽  
Marc D. Binder
Keyword(s):  
Time Course ◽  
Spike Frequency ◽  
Constant Current ◽  
Repetitive Firing ◽  
Bathing Solution ◽  
Appreciable Effect ◽  
Spike Frequency Adaptation ◽  
Hypoglossal Motoneurons ◽  
Frequency Adaptation ◽  
Later Phase

In response to constant current inputs, the firing rates of motoneurons typically show a continuous decline over time. The biophysical mechanisms underlying this process, called spike-frequency adaptation, are not well understood. Spike-frequency adaptation normally exhibits a rapid initial phase, followed by a slow, later phase that continues throughout the duration of firing. One possible mechanism mediating the later phase might be a reduction in the persistent sodium current ( INaP) that has been shown to diminish the capacity of cortical pyramidal neurons and spinal motoneurons to sustain repetitive firing. In this study, we used the anticonvulsant phenytoin to reduce the INaP of juvenile rat hypoglossal motoneurons recorded in brain stem slices, and we examined the consequences of a reduction in INaP on the magnitude and time course of spike-frequency adaptation. Adding phenytoin to the bathing solution (≥50 μM) generally produced a marked reduction in the persistent inward currents (PICs) recorded at the soma in response to slow, voltage-clamp triangular ramp commands (−70 to 0 mV and back). However, the same concentrations of phenytoin appeared to have no significant effect on spike-frequency adaptation even though the phenytoin often augmented the reduction in action potential amplitude that occurs during repetitive firing. The surprising finding that the reduction of a source of sustained inward current had no appreciable effect on the pattern of spike generation suggests that several types of membrane channels must act cooperatively to insure that these motoneurons can generate the sustained repetitive firing required for long-lasting motor behaviors.

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