What does it mean to “patch” a cell?
The reason scientists patch cells, or use the patch clamp technique, is
to listen in on a neuron’s activity. Neurons communicate using
electrical signals as their language, and they respond to electrical
signals from nearby neurons and cells. Using patch clamp methods to
record a neuron’s electrical activity is like eavesdropping on a
conversation happening next to you at lunch. Through a glass pipette,
researchers can monitor how a neuron communicates with the cells
around it. We can monitor these conversations to learn about the
physiology of different types of cells.
Patching a cell is the microscopic equivalent of sticking a straw into
a tennis ball, only much more delicately. Once your straw is attached to
the side of the tennis ball, you’re free to look through it and see what’s
going on inside the tennis ball. In the microscopic world, the straw is a
tiny glass tube called a pipette, and the tennis ball is the cell body of a
neuron. Researchers use microscopes and micromanipulators to place a
pipette delicately so that it gently presses into the cell body of a neuron
that is about 15-20 μm in diameter. Once the pipette is pressing on the
cell, a researcher can apply tiny amounts of negative pressure to suck
the cell membrane up against the opening of the pipette. With just the
right amount of negative pressure (basically sucking on a straw gently),
a researcher can open the portion of the membrane that’s inside the
glass pipette opening while leaving the rest of the neuron intact. Once
the membrane is open to the pipette, the neuron is considered
“patched”.
In my research, I patch neurons called Purkinje cells in brain slices
from the cerebellum of autistic mice. My goal is to look for differences
in the electrical activity of Purkinje cells and their surrounding cells
between the autistic and non–autistic mice. By finding differences in
electrical conversations in the brain slices from autistic mice, I hope to
determine what is different in the autistic brain.