Unfortunately, I don't have to help in this case because I work with the interaction between nanostructured materials and living cells. In addition, I beginning a few times to make some experiments involving hippocampal slices.

Dear Dr Grandhi,

I have not worked with MEA ever, while in conventional slice electrophysiological experiments you shall see an increase in the excitability of hippocampal CA1 neurones, possibly via blocking transient K channels. Please ensure that your slice is healthy and the signal you are measuring as spikes are sensitive to TTX (1 uM) in your system. You can add 4-AP (transient Kv channel blocker) as a positive control to check if your system is indeed capable of measuring the increase in spikes. 

Hope it helps!

Best Nand

Hello, since you get an increase in "noise" - it looks like your carbachol application is affecting hippocampal neuronal network activity, either on the level of synapses or action potential generation. The "noise's" frequency power could be tested with frequency analysis - clampfit or spike, and the "noise" should be block-able by TTX. You could retest with kainic acid.  If evoked str. pyr. located local potential is not affected, then might be stimulation strength to high, having max signal, needs a stimulation strength at spike threshold. best Thomas

Thanks for the information provided.

Best Regards,

Grandhi V Ramalingayya