15 research outputs found
The current situation and issues of the teaching of English in China
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Phase diagram of the vibrissa motoneuron model in the <i>g</i><sub>h</sub>-<i>I</i><sub>app</sub> plane.
<p>Regimes of STOs (light grey) and MMOs (dark grey) are obtained between the regimes of quiescence and tonic firing. The red line denotes Hopf bifurcation (HB), the green line denotes period doubling (PD) bifurcation, and the blue line denotes saddle-node of periodics (SNP) bifurcation.</p
Voltage fluctuations generated by stochastic noise.
<p>(A) Voltage time traces of the model neurons with <i>g</i><sub>M</sub> = 1 mS/cm<sup>2</sup>, <i>g</i><sub>NaP</sub> = 0.04 mS/cm<sup>2</sup>, <i>g</i><sub>h</sub> = 0, <i>I</i><sub>app</sub> = 1.4 µA/cm<sup>2</sup>, σ = 0.032 µA×ms<sup>1/2</sup>/cm<sup>2</sup>. For σ = 0, the model neurons are at rest for this parameter set. With noise, the membrane potential fluctuates. (B) The standard deviation of the voltage σ<sub>V</sub> as a function of the noise level σ. This figure demonstrates how the noise strength affects the magnitude of voltage fluctuations without any intrinsic STOs mechanism.</p
Phase diagrams of the vibrissa motoneuron model with <i>g</i><sub>h</sub> = 0.
<p>The dynamical states of the model neuron are plotted in the <i>g</i><sub>M</sub>-<i>I</i><sub>app</sub> plane (A) and in the <i>g</i><sub>M</sub>-<i>I</i><sub>app</sub> plane (B). A regime of STOs (light grey) is obtained between the regimes of quiescence and tonic firing. Red lines denote the Hopf bifurcation (HB), and blue lines denote the saddle-node of periodics (SNP) or period doubling (PD) bifurcations.</p
Bifurcation diagrams of the vibrissa motoneuron model with <i>g</i><sub>h</sub> = 0.
<p>The values of the membrane potential <i>V</i> (top panels) and the firing rate <i>f</i><sub>R</sub> (medium panels) are plotted as functions of <i>I</i><sub>app</sub> for fixed points (thin lines) and limit cycles (thick lines) for <i>g</i><sub>M</sub> = 0.4 mS/cm<sup>2</sup> (A), <i>g</i><sub>M</sub> = 1 mS/cm<sup>2</sup> (B) and <i>g</i><sub>M</sub> = 1.4 mS/cm<sup>2</sup> (C). For limit cycles, minimal and maximal voltages during the cycle are plotted. Solid lines denote stable solutions, and dotted lines denote unstable solutions. Stable sub-threshold oscillations are shown in blue, whereas stable tonic firing states are shown in solid thick black lines. Solid circles denote bifurcations from the following types: Hopf (HB), saddle-node of periodics (SNP) and period doubling (PD). Panels B<sub>1</sub>-B<sub>3</sub> at the bottom present the voltage time traces for <i>g</i><sub>M</sub> = 1 mS/cm<sup>2</sup> and <i>I</i><sub>app</sub> = 1.4, 1.6 and 1.8 µA/cm<sup>2</sup> respectively. These <i>I</i><sub>app</sub> values are denoted by the arrows below the abscissa in panel B (top).</p
Voltage time traces of the model neuron in response to step current injection at <i>t</i> = 0.
<p>Parameters are as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109205#pone-0109205-g003" target="_blank">Figure 3</a> (<i>g</i><sub>h</sub> = 0.3 mS/cm<sup>2</sup>). The values of <i>I</i><sub>app</sub> are written in units of µA/cm<sup>2</sup>. (A) <i>I</i><sub>app</sub> = 1.41, the membrane potential of the neuro goes to rest. (B) <i>I</i><sub>app</sub> = 1.8, the neuron exhibits sub-threshold oscillations. (C) <i>I</i><sub>app</sub> = 1.9, the neuron fires in an MMOs mode, with 3 sub-threshold oscillations between each pair of consecutive spikes. (D) <i>I</i><sub>app</sub> = 2.0, the neuron fires in an MMOs mode. The number of STOs between pairs of consecutive spikes switches alternately between 1 and 2. (E) <i>I</i><sub>app</sub> = 2.06, the neuron fires in an MMOs mode with one STO between two consecutive spikes. (F) <i>I</i><sub>app</sub> = 2.1, the neuron fires aperiodically. (G) <i>I</i><sub>app</sub> = 2.12, The neuron fires two spikes, shows one STO, and then the cycle starts again. (H) <i>I</i><sub>app</sub> = 2.2, the neuron fires tonically. The dynamical states are indicated above each panel.</p
Properties of firing patterns without and with an intrinsic MMOs-generating mechanism.
<p>The firing rate <i>f</i><sub>R</sub> (I), the coefficient of variation CV (II) and the time period <i>t</i><sub>p</sub>, computed assuming a Bernoulli process (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109205#pone.0109205.e009" target="_blank">Equation 3</a>) (III) are plotted as a function of <i>I</i><sub>app</sub> for <i>g</i><sub>h</sub> = 0 (A) and <i>g</i><sub>h</sub> = 0.3 mS/cm<sup>2</sup> (B). The colors of the lines denoting the values of σ (in µA×ms<sup>1/2</sup>/cm<sup>2</sup>) are: black – 0, red – 0.01, green – 0.032, blue – 0.1 and orange – 0.32. The vertical dotted lines denote the <i>I</i><sub>app</sub> values of the transitions between different dynamical states (quiescence, STOs, MMOs and tonic firing) of the noiseless neuron.</p
Voltage time traces of the model neuron in response to step current injection at <i>t</i> = 0.
<p>The values of <i>I</i><sub>app</sub> are indicated to the right of the traces. (A) <i>g</i><sub>h</sub> = 0, σ = 0.01 µA×ms<sup>1/2</sup>/cm<sup>2</sup>. The noiseless neuron does not exhibit MMOs, but this level of noise generates MMOs near the transition between quiescence and tonic firing. (B) <i>g</i><sub>h</sub> = 0, σ = 0.1 µA×ms<sup>1/2</sup>/cm<sup>2</sup>. For this larger noise level, MMOs are generated in a more widespread <i>I</i><sub>app</sub> regime. (C) <i>g</i><sub>h</sub> = 0.3 mS/cm<sup>2</sup>, σ = 0.01 µA×ms<sup>1/2</sup>/cm<sup>2</sup>. The noiseless neuron generates MMOs. This level of noise increases the <i>I</i><sub>app</sub> regime in which MMOs are obtained only slightly. The MMOs are less ordered, and the number of STOs between spikes varies from one inter-spike interval to another. (D) <i>g</i><sub>h</sub> = 0.3 mS/cm<sup>2</sup>, σ = 0.1 µA×ms<sup>1/2</sup>/cm<sup>2</sup>. MMOs appear in <i>I</i><sub>app</sub> regimes in which the noiseless neuron is quiescent or fires tonically, and the firing patterns look less ordered.</p
Bifurcation diagrams of the vibrissa motoneuron model with <i>g</i><sub>h</sub> = 0.3 mS/cm<sup>2</sup>.
<p>(A) The values of the membrane potential <i>V</i> (top panel) and the firing rate <i>f</i><sub>R</sub> (bottom panel) are plotted as functions of <i>I</i><sub>app</sub> for fixed points (thin lines) and limit cycles (thick lines) for <i>g</i><sub>M</sub> = 1 mS/cm<sup>2</sup>. For limit cycles, minimal and maximal voltages during the cycle are plotted. Solid lines denote stable solutions, and dotted lines denote unstable solutions. Stable sub-threshold oscillations are shown in blue, whereas stable tonic firing states are shown in solid thick black lines. Solid circles in the top panels denote bifurcations from the following types: Hopf (HB), saddle-node of periodics (SNP) and period doubling (PD). The firing rate in the MMOs state is plotted in red in the bottom panel. (B) The firing rate <i>f</i><sub>R</sub> in the MMOs state is plotted as a function of <i>I</i><sub>app</sub> at a larger scale. The types of mixed mode states (see text, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109205#pone-0109205-g004" target="_blank">Figure 4</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0109205#pone.0109205-Ermentrout1" target="_blank">[23]</a>) are indicated above the curve.</p
