Ca2+-dependent K+ currents and spike-frequency adaptation in medial entorhinal cortex layer II stellate cells

In this study, we characterize the electrophysiological and morphological properties of spiny principal neurons in the rat lateral amygdala using whole cell recordings in acute brain slices. These neurons exhibited a range of firing properties in response to prolonged current injection. Responses varied from cells that showed full spike frequency adaptation, spiking three to five times, to those that showed no adaptation. The differences in firing patterns were largely explained by the amplitude of the afterhyperpolarization (AHP) that followed spike trains. Cells that showed full spike frequency adaptation had large amplitude slow AHPs, whereas cells that discharged tonically had slow AHPs of much smaller amplitude. During spike trains, all cells showed a similar broadening of their action potentials. Biocytin-filled neurons showed a range of pyramidal-like morphologies, differed in dendritic complexity, had spiny dendrites, and differed in the degree to which they clearly exhibited apical versus basal dendrites. Quantitative analysis revealed no association between cell morphology and firing properties. We conclude that the discharge properties of neurons in the lateral nucleus, in response to somatic current injections, are determined by the differential distribution of ionic conductances rather than through mechanisms that rely on cell morphology.

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Bumps, Breathers, and Waves in a Neural Network with Spike Frequency Adaptation

Physical Review Letters ◽

10.1103/physrevlett.94.148102 ◽

2005 ◽

Vol 94 (14) ◽

Cited By ~ 93

Author(s):

S. Coombes ◽

M. R. Owen

Keyword(s):

Neural Network ◽

Spike Frequency ◽

Spike Frequency Adaptation ◽

Frequency Adaptation

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Cholinergic Modulation of Spike Timing and Spike Frequency Adaptation in Neocortical Neurons

Computational Neuroscience ◽

10.1007/978-1-4615-4831-7_49 ◽

1998 ◽

pp. 291-296

Author(s):

A. C. Tang ◽

A. M. Bartels ◽

T. J. Sejnowski

Keyword(s):

Spike Timing ◽

Spike Frequency ◽

Spike Frequency Adaptation ◽

Cholinergic Modulation ◽

Neocortical Neurons ◽

Frequency Adaptation

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Spike frequency adaptation studied in hypoglossal motoneurons of the rat

Journal of Neurophysiology ◽

10.1152/jn.1995.73.5.1799 ◽

1995 ◽

Vol 73 (5) ◽

pp. 1799-1810 ◽

Cited By ~ 101

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)

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

eLife ◽

10.7554/elife.44954 ◽

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.

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