How to figure out if more than 1 electrode is picking u

Hi,

I have been successful in recording multiple retinal ganglion cells using the MEA system. Now, I am trying to analyze my data using an offline spike sorting problem. I can think of 2 situations that I have to be careful about:

1) a particular electrode picks up more than 1 cell. This should be solved easily using principal component analysis, where the two or more cells should have different clusters.

2) More than 1 electrode picks up the spiking from the same cell. How do differentiate this? Please give me advice on how to do this, as if this is going on, I will be overestimating the number of ganglion cells that I am recording from.


Any help would be greatly appreciated.
Thank you,
Muhammad

Dear Muhammad,
with an electrode distance of more than 50µm, usually a spike
is not picked up by more than one electrode. This topic is
described in Egert et al., ExpBrainRes, 2002.
Algorithms that may be usefull for you are also described in
Segev et al. Nat Nsci, 2004 and other papers from Michael
Berrys lab.

Frank (MCS)

Depends of mea array type /layout, preparation,... In classical paper of Meister et al , J.Neurosci.Methods, 51, 1994 the authors were able to pick up the same cell AP at "several neighbouring electrodes" using custom MEA with 70µm spacings. I recorded ocassionally the same retinal ganglion cell activity at few channels using standard planar MEA (MCS) with 100µm spacings.