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Recording neuronal activity using electrophysiology equipment

Today in the lab I was doing an electrophysiology experiment, specifically known as the patch-clamp technique. The idea is to use an electrode to record the electrical activity of a single neuron grown in vitro. It is a relatively difficult procedure to perform at first, but once you get the hang of it, it becomes much easier. So far, for the past two months, I have been able to record from about 100 individual neurons, each one taking me approximately 20 minutes.

The below images show examples of what the neurons looked like under the microscope. More details on the experiment and the methods I was using are given below.

These are some of the neurons from which I recorded electrical activity today. Image (A) shows a neuron under a DIC microscope. Images B-D show neurons labelled with a fluorescent reporter.
These are some of the neurons from which I recorded electrical activity today. Image (A) shows a neuron under a DIC microscope. Images B-D show neurons labelled with a fluorescent reporter.

Electrophysiology involves a lot of physics and electronics knowledge, in order to understand how the neuron’s activity is recorded, and how to operate the recording equipment. An image of the various recording equipment I was using today is shown below. I labelled the major parts for those who are curious. The set-up basically involves a DIC (differential interference contrast) microscope attached to various electronic devices.

The various equipment I was using for my experiment.
The various equipment I was using for my experiment.

Detailed methods of today’s experiment

Recordings were performed using a computer-controlled patch clamp amplifier operated with specialised computer software. Whole-cell voltage clamp recordings were performed at a holding potential of -65 mV at room temperature. Whole-cell configuration was achieved by applying a light suction pulse by mouth while simultaneously delivering a brief 1 V electrical pulse. Compensation was applied for the fast and slow capacity transients. A seal test (a 10 mV test pulse) was applied through the recording electrode to measure the access resistance at the beginning of every 10-second recording.