Dynamics and diversity in interneurons: a model exploration with slowly inactivating potassium currents

Saraga, Fernanda; Skinner, Frances K.

doi:10.1016/s0306-4522(02)00168-9

Cited by 10 publications

(4 citation statements)

References 48 publications

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“…While examining the properties of single action potentials in BNST ALG neurons it was noted that transient (10 ms), subthreshold, depolarizing current injection could elicit a voltage response whose decay far outlasted the normal time constant for membrane discharge. Similar slow depolarizing potentials have been observed in neurons of the entorhinal cortex and hippocampus (Saraga and Skinner 2002), where they were attributed to the activation of a slowly inactivating persistent sodium current (I NaP ). Consequently, we next examined BNST ALG neurons for the presence of the persistent sodium current (I NaP ).…”

Section: Expression Of the Inwardly Rectifying Potassium Currentsupporting

confidence: 65%

Differential Expression of Intrinsic Membrane Currents in Defined Cell Types of the Anterolateral Bed Nucleus of the Stria Terminalis

Hammack¹,

Mania²,

Rainnie³

2007

Journal of Neurophysiology

119

178

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The anterolateral group of the bed nucleus of the stria terminalis (BNST(ALG)) plays a critical role in a diverse array of behaviors, although little is known of the physiological properties of neurons in this region. Using whole cell patch-clamp recordings from rat BNST(ALG) slices in vitro, we describe three distinct physiological cell types. Type I neurons were characterized by the presence of a depolarizing sag in response to hyperpolarizing current injection that resembled activation of the hyperpolarization-activated cation current I(h) and a regular firing pattern in response to depolarizing current injection. Type II neurons exhibited the same depolarizing sag in response to hyperpolarizing current injection, but burst-fired in response to depolarizing current injection, which was indicative of the activation of the low-threshold calcium current I(T). Type III neurons did not exhibit a depolarizing sag in response to hyperpolarizing current injection, but instead exhibited a fast time-independent rectification that became more pronounced with increased amplitude of hyperpolarizing current injection, and was indicative of activation of the inwardly rectifying potassium current I(K(IR)). Type III neurons also exhibited a regular firing pattern in response to depolarizing current. Using voltage-clamp analysis we further characterized the primary active currents that shaped the physiological properties of these distinct cell types, including I(h), I(T), I(K(IR)), the voltage-dependent potassium current I(A), and the persistent sodium current I(NaP). The functional relevance of each cell type is discussed in relation to prior anatomical studies, as well as how these currents may interact to modulate neuronal activity within the BNST(ALG).

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Section: Expression Of the Inwardly Rectifying Potassium Currentsupporting

confidence: 65%

Differential Expression of Intrinsic Membrane Currents in Defined Cell Types of the Anterolateral Bed Nucleus of the Stria Terminalis

Hammack¹,

Mania²,

Rainnie³

2007

Journal of Neurophysiology

119

178

View full text Add to dashboard Cite

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“…The role of the window I Na in achieving low firing rates was considered in [13,18]. The fact that slowly inactivated K + currents can induce delay to action potential firing and bursting was also described in [13,39]. The stuttering pattern displayed by our model is an example of “elliptic bursting” [18,20,40] (also named “SubHopf/Fold cycle” [19]).…”

Section: Discussionmentioning

confidence: 99%

Mechanisms of Firing Patterns in Fast-Spiking Cortical Interneurons

et al. 2007

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Cortical fast-spiking (FS) interneurons display highly variable electrophysiological properties. Their spike responses to step currents occur almost immediately following the step onset or after a substantial delay, during which subthreshold oscillations are frequently observed. Their firing patterns include high-frequency tonic firing and rhythmic or irregular bursting (stuttering). What is the origin of this variability? In the present paper, we hypothesize that it emerges naturally if one assumes a continuous distribution of properties in a small set of active channels. To test this hypothesis, we construct a minimal, single-compartment conductance-based model of FS cells that includes transient Na+, delayed-rectifier K+, and slowly inactivating d-type K+ conductances. The model is analyzed using nonlinear dynamical system theory. For small Na+ window current, the neuron exhibits high-frequency tonic firing. At current threshold, the spike response is almost instantaneous for small d-current conductance, g d, and it is delayed for larger g d. As g d further increases, the neuron stutters. Noise substantially reduces the delay duration and induces subthreshold oscillations. In contrast, when the Na+ window current is large, the neuron always fires tonically. Near threshold, the firing rates are low, and the delay to firing is only weakly sensitive to noise; subthreshold oscillations are not observed. We propose that the variability in the response of cortical FS neurons is a consequence of heterogeneities in their g d and in the strength of their Na+ window current. We predict the existence of two types of firing patterns in FS neurons, differing in the sensitivity of the delay duration to noise, in the minimal firing rate of the tonic discharge, and in the existence of subthreshold oscillations. We report experimental results from intracellular recordings supporting this prediction.

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“…The role of the window I Na in achieving low firing rates was considered in [13,18]. The fact that slowly inactivated K þ currents can induce delay to action potential firing and bursting was also described in [13,39]. The stuttering pattern displayed by our model is an example of ''elliptic bursting'' [18,20,40] (also named ''SubHopf/Fold cycle'' [19]).…”

Section: Relation To Previous Theoretical Work and Models Of Fs Cellsmentioning

confidence: 99%

Mechanisms of Firing Patterns in Fast-Spiking Cortical Interneurons

et al. 2005

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Cortical fast-spiking (FS) interneurons display highly variable electrophysiological properties. Their spike responses to step currents occur almost immediately following the step onset or after a substantial delay, during which subthreshold oscillations are frequently observed. Their firing patterns include high-frequency tonic firing and rhythmic or irregular bursting (stuttering). What is the origin of this variability? In the present paper, we hypothesize that it emerges naturally if one assumes a continuous distribution of properties in a small set of active channels. To test this hypothesis, we construct a minimal, single-compartment conductance-based model of FS cells that includes transient Na, and slowly inactivating d-type K þ conductances. The model is analyzed using nonlinear dynamical system theory. For small Na þ window current, the neuron exhibits high-frequency tonic firing. At current threshold, the spike response is almost instantaneous for small d-current conductance, g d , and it is delayed for larger g d . As g d further increases, the neuron stutters. Noise substantially reduces the delay duration and induces subthreshold oscillations. In contrast, when the Na þ window current is large, the neuron always fires tonically. Near threshold, the firing rates are low, and the delay to firing is only weakly sensitive to noise; subthreshold oscillations are not observed. We propose that the variability in the response of cortical FS neurons is a consequence of heterogeneities in their g d and in the strength of their Na þ window current. We predict the existence of two types of firing patterns in FS neurons, differing in the sensitivity of the delay duration to noise, in the minimal firing rate of the tonic discharge, and in the existence of subthreshold oscillations. We report experimental results from intracellular recordings supporting this prediction.

show abstract

Dynamics and diversity in interneurons: a model exploration with slowly inactivating potassium currents

Cited by 10 publications

References 48 publications

Differential Expression of Intrinsic Membrane Currents in Defined Cell Types of the Anterolateral Bed Nucleus of the Stria Terminalis

Differential Expression of Intrinsic Membrane Currents in Defined Cell Types of the Anterolateral Bed Nucleus of the Stria Terminalis

Mechanisms of Firing Patterns in Fast-Spiking Cortical Interneurons

Mechanisms of Firing Patterns in Fast-Spiking Cortical Interneurons

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