Many experiments in neuroscience are done using a technique called voltage clamping. In this technique, an experimenter can rapidly (within microseconds) control the voltage of the cell and measure the resultant electrical current that flows through various channels. The system will lock the voltage at the desired level regardless of the openings or closings of voltage-gated channels. The recordings thus reflect the summed total of thousands to millions of potassium, sodium and other ion-selective channels.

Imagine just the axon of a neuron voltage-clamped at -70 mV for 5 milliseconds, then %u201Cjumped%u201D to 0 mV for 5 ms, then jumped back to -70 mV. First, draw a diagram showing the voltage protocol that is being used. Next, draw in a separate diagram he summed electrical currents you would expect to see in this preparation. Be sure to label the axes. Then imagine that tetrodoxin, a toxin from puffer fish that blocks voltage-gated sodium channels, is added. Draw on a separate diagram the electrical current one would expect to see in this condition using the same voltage protocol. Now, wash out the tetrodotoxin and add tetraethylammonium (TEA), that blocks voltage-gated potassium channels. Draw on a separate diagram the electrical current one would expect to see in this condition using the same voltage protocol. Finally, add both TTX and TEA and draw on a separate diagram the electrical current one would expect to see in this condition using the same voltage protocol.