We are sorry, but NCBI web applications do not support your browser and may not function properly. More information

Results: 5

1.
Fig. 1

Fig. 1. From: Multiphysics Neuron Model for Cellular Volume Dynamics.

Diagram of our neuron model: time-varying variables and the physical principles connecting them. In addition to the H-H model (indicated in gray), we employed multiple physical principles, such as conservation theory, diffusion theory, and electrochemical equilibrium, to couple newly introduced time-varying variables, such as the intracellular ion concentration and the cell volume.

Jonghwan Lee, et al. IEEE Trans Biomed Eng. 2011 October;58(10):3000-3003.
2.
Fig. 2

Fig. 2. From: Multiphysics Neuron Model for Cellular Volume Dynamics.

Representative numerical solutions of our neuron model. (A)–(D) Total (Na+K) intracellular concentration and the cell volume, as well as the membrane potential, varied during excitation. The duration of stimulation was 1 ms, and the initial cell diameter was 10 μm. The vertical gray lines indicate the moment of stimulation. (E) Various shapes of the optical signals observed experimentally in the literature are very similar to our calculated cellular volume responses. Data were extracted from the literature (left and center from [1], and right from [2]). All horizontal scale bars indicate 10 ms.

Jonghwan Lee, et al. IEEE Trans Biomed Eng. 2011 October;58(10):3000-3003.
3.
Fig. 5

Fig. 5. From: Multiphysics Neuron Model for Cellular Volume Dynamics.

Positive and negative feedbacks among variables during initiation of the action potential. The stimulation current increases the membrane potential, as well as the transition rate and the permeability of the sodium channel, while the increased sodium channel conductivity further raises the membrane potential (positive feedback), thus initiating the action potential. Our model suggests that the increased sodium current raises the intracellular sodium concentration and decreases the equilibrium potential of the sodium ion channel, while the decreased equilibrium potential inhibits the increase of membrane potential (negative feedback), thus suppressing the initiation of the action potential. This is why the threshold was slightly higher in our model than in the H-H model. The negative feedback of the volume to the ion concentration occurs with a time delay due to the finite water diffusion speed. Gray color indicates variables and feedbacks from the H-H model.

Jonghwan Lee, et al. IEEE Trans Biomed Eng. 2011 October;58(10):3000-3003.
4.
Fig. 3

Fig. 3. From: Multiphysics Neuron Model for Cellular Volume Dynamics.

Analysis of neuronal volume responses for a single stimulation. (A) Distribution of volume response patterns in the parameter space. Green, blue, and red colors indicate the patterns B, C, and D, respectively. Only points where an action potential was fired are presented. (B) Distribution of the volume response patterns for four selected initial cell diameters. (C) Peak and plateau volume changes as a function of the injected charge density. The color represents the initial cell size, ranging from 10 (cyan) to 25 μm (magenta). (D) Distribution of volume response patterns in the parameter space of the charge density and the cell size. The dashed line b indicates the threshold of action potential firing. The dashed lines c and d indicate the boundaries among the patterns B (green), C (blue), and D (red).

Jonghwan Lee, et al. IEEE Trans Biomed Eng. 2011 October;58(10):3000-3003.
5.
Fig. 4

Fig. 4. From: Multiphysics Neuron Model for Cellular Volume Dynamics.

Large-time-scale neuronal volume responses for repetitive stimulation. (A) Cellular volume change and membrane potential for two selected stimulation amplitudes. Top traces show the cell volume change during 1 min, while middle and bottom traces show the cell volume and membrane potential changes during the first 1 s. The stimulation was applied at 20 Hz for 20 s (the thick horizontal bar). (B) Behavior of the volume response in the parameter space of the stimulation amplitude and frequency. The maximum volume change with its sign (top) and the average slope of the volume change for the first 1 s (bottom) are presented. The color represents the stimulation frequency, ranging from 5 (blue) to 50 Hz (red). The dashed line a indicates the threshold current for inducing long-term volume responses. In the region between the dashed lines b and c, the maximum change was larger than zero even though the initial slope was negative. The initial cell diameter and the current pulse width were fixed at 10 μm and 1 ms, respectively.

Jonghwan Lee, et al. IEEE Trans Biomed Eng. 2011 October;58(10):3000-3003.

Supplemental Content

Recent activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...
Write to the Help Desk