Experiment Five: Microstimulation

Since nerves use electricity to communicate, they can be

manipulated with electricity as well

Luigi Galvni discovered in the 1700s that electricity applied to the nerves of frog legs caused the large

muscles to twitch

Is “animal” electricity different than the electricity of lightening storms?

Galvani hung frog legs off his back porch during thunderstorms and watched the legs twitch.

Can electricity applied to brain modify body function?

Hitzig and Fritsch (1870): applied electrical current to dog cerebral cortex showed that stimulating different parts of brain causes

different types of movement

Present Day Neuromodulation Applications

Deep Brain Stimulation Retinal Prosthetic

Which can help the symptoms of Parkinson’s but sometimes causes increased complusive behavior like gambling

implanted chip

Exercise 1: Cockroach Leg Microstimulation Set up

Exercise 2: Response of motor neurons to amplitude and frequency

High amplitudeLow frequency

Low amplitudeHigh frequency

High amplitude = More Neural Tissue Affected

High frequency = Individual Neurons Firing More Spikes (up to a limit?)

Exercise 3: Recording and spike patterns from ganglia

Identify relationships between leg movements and ganglia spike patterns

Exercise 3B: Stimulation of metathoracic ganglion/ Effect of spike patterns and amplitude on movement

“Copy Paste” or “Read Write”

Exercise 3B: Stimulation of metathoracic ganglion/ Effect of spike patterns and amplitude on movement