A simple and effective method for obtaining stable in vivo whole-cell recordings from visual cortical neurons.

We describe a simple and effective method for obtaining stable in vivo whole-cell recordings in cat visual cortex. The core of the new approach is to prevent brain pulsation by retaining the dura mater. After being treated with an enzyme (collagenase), the dura became soft enough to allow easy penetration by a patch-clamp electrode with negligible damage to the tip. The procedure is as simple as those used for extracellular recordings, and all the intricate steps required for conventional techniques are no longer necessary. The reliability of this approach is demonstrated by stable and sustained intracellular recordings and high-quality intracellular staining. The method is especially effective for studying small neurons in the superficial layers immediately below the dura.