MEA and patch clamp recordings

Hello,

are there any recommendations how to combine MEA chips with DIC or gradient contrast for visual identification of neurones to be selected for whole cell patch clamp recordings? How do I get a good enough image despite the chip in the optical path, and how can I avoid electrical interference between the simultaneous intracellular and the field potential measurements?

Ringo

Dear Ringo,

we do have MEAs which are as thin as a standard glas coverslip (about 180µm). These offer excellent optical properties. The tracks can be made from a transparent material like Indium Tinoxide (ITO) to further enhance optical properties. However electrodes are made from Titanium nitrate for the better recording properties of this material. So you will habve to select a neuron near a MEA electrode - but not exactly above the electrode for whole cell patch clamp.

The MEA amplifier comes in a shielded housing. If placed on a microscope Table there is usually no further shielding required and it should not interfere with the patch clamp recording. However you should of course ground the perfusion and patch electrode holder to avoid "antenna" effects.

Thomas

Hello Thomas,

thank you for these helpful general suggestions.
More specifically: how do MEA and patch clamp go down with recording from acute slices? Ayanda's home page recommends the rather opaque 3D chips for acute slices, whereas they mention ITO chips for slice cultures and dissociated cell cultures. I guess that the application is a matter of trial and error, but I am worried that I have not seen a single publication where patch clamp was done with an acute slice placed on a MEA chip. Are there any alternatives?

Ringo

Dear Ringo,

You are right, that there is currently not much published about patch clamp recording from acute slices and simultaneous MEA recording. However there are several papers demonstrating that patch clamp and MEA recording can be done simultaneously (eg. Soriano FX, Papadia S, Hofmann F, Hardingham NR, Bading H, Hardingham GE. Preconditioning doses of NMDA promote neuroprotection by enhancing neuronal excitability.J Neurosci. 2006 Apr 26;26(17):4509-18.)
I think this fact clearly shows that this combination can be done from a technical side.

Acute slices can be recorded from Ayandas 3D MEAs or our standard MEAs with TiN electrodes. It is mostly a matter of personal preference, as both type of MEAs have their pros and cons in this application.
The optical properties however should not represent a serious bottleneck, as the slice itself is a bit opaque. However, if you require better optical properties, you can simply switch to MEAs with TiN electrodes as the mentioned thin MEAs.

Greetings

Thomas