patch-clamp technique

The patch-clamp technique is a way to eavesdrop on the tiny electrical currents that flow through a living cell's membrane. A researcher presses the polished tip of a fine glass pipette against the cell's surface and gently applies suction, forming a seal so tight that almost no current can leak around the edges. Through that little sealed patch of membrane, a sensitive amplifier can measure currents as small as those passing through a single ion channel — one of the protein pores that let charged atoms cross the membrane.

The same setup is wonderfully flexible. Left as it is, it records one channel at a time; if the researcher instead breaks through the membrane under the pipette, it reads the electrical behavior of the whole cell at once, including the voltage swings of an action potential — the brief electrical pulse a neuron uses to signal. The experimenter can also choose to hold the voltage steady and watch the current (voltage clamp), or hold the current and watch the voltage (current clamp), which together expose how a neuron's electrical machinery actually works.

Erwin Neher and Bert Sakmann developed the method in the late 1970s, and it gave neuroscience its first direct look at single ion channels opening and closing. They were awarded the 1991 Nobel Prize in Physiology or Medicine for the work.