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Patch Clamp Electrophysiology
One of the first things we talked about was her work with patch clamping. Emily explained the process extremely well and we wanted to include some images to further demonstrate the technique and make it easier for visual learners.
The image to the left is what you would see under the microscope using infrared light. Here you can see the pipette coming down from the left side of the image and the neuron it is patched to just below the tip near the middle of the image. Getting both the pipette and the cell in focus together is a challenge: connecting the two is extremely difficult.
Image from: Dr. Ainhara Aguado, Ruhr University Bochum, Germany
Once connected to the cell, there are a few ways to record the action potentials (the electrical current that goes through the axon). You can see these various set-ups in the image below. The set-up Emily uses is Whole-cell Recording, which is the very bottom left panel. If you notice the arrows in the image, each technique starts with the top left image where the pipette is brought to the cell’s surface, then with mild suction it moves to the image in the top middle where the pipette is attached to the surface. Emily’s technique then uses a strong suction pulse to break the surface of the cell allowing the pipette access to the inside of the cell body, or soma.
Image from: Patch me if you can – What is the patch-Clamp Technique?, puzzledponderer.wordpress.com
Once you’re connected, what does the data look like?
You can see to the right a sample data recording from a neuron. Notice that like other electricity readings you may have seen, the unit of measurement is in voltage; in this case mV (milliVolts), which is a fraction of a volt. Additionally, notice the amount of time that passes for each spike to occur. It’s not very long! The time scale is in ms (milliseconds), which is a fraction of a second. Each spike you see on this image represents one action potential (one electrical signal that passes the axon hillock and travels down the axon.
In addition to her discussion of the patch clamping technique, Emily mentioned the case of a split brain patient. See the video below for an awesome and short documentary clip about a split brain patient right here at Dartmouth.
Let us know what you thought about the episode and if there are anymore resources you’d like to see put up about this topic!