6. Sample nerve cells

6.1 Cell with Dendrite-Soma-Axon

This simple three-section cell is useful for viewing and learning about impulse propagation along the full length of the cell. It was set up with a synapse in the middle of the single dendrite and a stimulating electrode at the distal end of the axon. You can:

• set either stimulus to zero to observe the cell's behavior resulting from the individual stimulii.
• change the placement of both the synapse and the electrode, and
  • the synaptic conductance,
  • the stimulating current parameters.
• use the electrode to voltage clamp any where in the cell and observe the quality of spatial uniformity (which is necessary to yield accurate and undistorted current records).

In particular, you should look at the effect of temperature and axon diameter changes. Click here toRUN this program.

6.2 Three Dendrites-Soma-Axon

A. This is a similar simple nerve cell but now with:

• three dentrites and
• 2 synapses whose locations and strengths are under cursor point control.

Click to RUN this program.

B. Another, more complete, version of this application has a structure similar to that of a motorneuron with an axon hillock, an initial segment of axon leading to a myelinated fiber. The channel densities in each of these elements have been laboriously chosen to match as many experimental observations on the spinal motorneuron of the cat. The lengths of the initial myelinated segments had to be carefully chosen to allow antidromic impulse invasion of the soma. The synaptic parameters have been collected into a simgle panel and a slider is used to locate 3 synapses on three different dendrites. The voltages in the 3 dendrites are shown in different colors in the display of spatial voltage distributions. RUN this program

This cell is also used to examine spatial and temporal integration or summation of synaptic inputs.