cLABs - Voltage and Patch Clamp Simulation

Voltage- and Patch-Clamp Experiments in Virtual Computer Laboratories (cLABs-Neuron)

Hans A. Braun; Horst Schneider; Bastian Wollweber; Heiko B. Braun & Karlheinz Voigt

Institute of Physiology, Deutschhausstr. 2, 35037 Marburg, Germany

Introduction

  • cLABs is a series of multimedial programs for teaching dynamic biological and physiological mechanisms in an interactive and virtual environment which allows users to perform their own sets of experiments.
  • cLABs programs are equally suitable for universities and biology classes at schools as well as for private studies.
  • cLABs-Neuron, our latest cLABs-Software, demonstrates the interrelations between ion channel dynamics and membrane currents and voltages. It consists of the modules:
    1. Membrane Properties
    2. Ion Channels
    3. Voltage-/Current-Clamp Experiments

I. Membrane Properties

This module provides animations and simulations to basic functions of neuronal membrane properties which are described in terms of their electrical equivalents.

Electrical Equivalents
Illustrates the functional membrane properties (= bilipid layer and ion channels) and their electrical equivalents (= membrane capacitance and resistance).

RC-Circuit
Visualises current flows and potential changes across a resistor and a capacitor in a RC-parallel circuit.

RC-Lab
Allows experiments to examine the voltage changes that occur in a RC-parallel circuit when current pulses are applied and no active elements (e.g. ion channels) are involved.
  • Resistance and capacitance of the RC-circuit can be changed.
  • A variable number of current pulses of pre-selectable amplitude, duration and delay can be applied.

Conductance
This interactive section can be used to learn how the membrane potential can be changed with alterations of ionic conductances. For an intuitive understanding we use a simplified circuit which only consider the Na and K currents and even neglect the membrane capacitance (stationary condition).

  • You can move the sliders of the potentiometers to see how the membrane potential and currents change as a function of the ionic conductances.
  • The buttons allow pre-sets of the conductances to minimal, maximal or equal values and also simulates the changes during an action potential.

II. Ion Channels

The ion-channel module embraces the structure, gating mechanisms and pharmacological sensitivity of voltage dependent Na and K ion channels.

  • The first part of the program introduces and describes the main characteristics of one- and two-gate ion channels with a selectivity for potassium and sodium, respectively.
  • A following interactive section simulates single channel Na- and K-currents. Here, the user can de- or repolarize a virtual membrane and record the resulting ion currents, as well as watch the gating mechanisms.

Single Channel Lab
This virtual laboratory is the main part of the module and shows the time course of Na- and K-currents, according to the number of ion channels in a virtual cell membrane.

The user can stimulate a certain number of single Na- and K-ion channels and the record the respective currents, which are add up to a virtual whole cell current.

III. Voltage-/Current-clamp Experiments

The third module provides a virtual lab for voltage- and current-clamp experiments with different types of neurones and also explains background and concepts of the recording techniques.

Recording Techniques
This interactive module shows step-by-step how the generation of actions potentials on current injection leads to the concepts of current-recordings in a voltage-clamp circuit. Recording and stimulating electrodes can be inserted into virtual neurons. Voltage- and current-clamp recordings during the application of hyper- or depolarising stimuli of different amplitudes illustrate the transitions from purely passive to active neuron responses.

Voltage/Current-Clamp Lab
A virtual computer laboratory for both current- and voltage-clamp experiments with mathematically simulated neurons.

The simulations are based on simplified Hodgkin-Huxley (HH) type algorithms.

A neuron editor allows the user to change the neuron’s parameters and to develop and save his/her own favourite neurons.

Download further details of this product: PowerPoint file (3.9MB)

Price: £310 (Institutional, multi-user licence)

Supported by: BM&T Heidelberg/Marburg DAQ-Solutions, Lohra, TransMIT, Giessen

Click on one of the above screen grabs to see full size image.