Patch-Clamp Recordings from the Dendrite of a Dopaminergic Neuron in a Brain Slice

In this procedure, transfer a brain slice to the recording chamber. Anchor the slice at the bottom of the recording chamber with a platinum ring, and ensure that the slice is of good quality with a smooth, even surface. Then, select a neuron with a dendrite extending over a long distance in the same plane, and ensure that the dendrite of interest can be followed to a well-defined soma. Next, fill the patch pipette with electrode solution.

To patch the dendrite in cell-attached mode, identify and focus on a portion of the dendrite. Apply positive pressure to the pipette, and lower it using the micromanipulator. Then, position the pipette close to the membrane, and adjust the pressure in order to create a small dimple. Subsequently, release the pressure on the pipette tip and patch the dendrite while controlling the pipette resistance. Try to obtain a seal resistance larger than 1 giga ohm, at best between 3 and 10 giga ohms for cell-attached recordings.

Afterward, retract the pipette away from the membrane by a couple of micrometers to avoid deformation of the dendrite. The action currents seen here represent the spontaneous action potentials of nigral neurons. To suppress the action currents, apply calcium and sodium channel blockers to ACSF. Then, apply a voltage step of negative 90 millivolts from a holding potential of 0 millivolts to evoke the hyperpolarization-activated cation current.