Two questions about hc-2

Thanks very much for Gautam’s reply! But I still have two questions.

1. I'm still confused about the unit of the LFP waveform in the *.eeg files. In the "crcns.org hc2 data description" pdf file, it is mentioned that the neurophysiological signals were amplified 1,000x, but you said  the voltage was amplified 20,000x, why?  Additionally, in the 16-bit coded numbers, whether it includes a sign bit?

2. I've comprehended that the spike clusters are unrelated to the number of channels, but I want to know that how a specified cluster is assigned to the corresponding electrode. In the "LoadCluRes" script, it is commented that "Map is a matrix displaying the correspondance between new cluster numbers (first column) and inital shank # (second column) and cluster # (third column)". In the matrix "Map" of "ec013.527", for example, the 9th line is " 9 1 12", what the "12" means? In otheer words, how can I find the spike train of a neuron is recorded by which electrode?

Thamks!

Hello, thanks for the follow up.

1. Sorry for the confusion. Indeed, the amplification factor is 1,000x, and not 20,000x. The 16-bit number includes a sign bit, and spans a 20 V range.

2. Since one can specify which shanks to load using LoadCluRes, the first column contains arbitrarily assigned cluster numbers. The 2nd column indicates the shank on which the spike was detected, and the 3rd column indicates the original number assigned to a given cluster. Thus, if there were 20 unique clusters detected on a shank, the 3rd column would contain values ranging from 1 to 20.

Best
Gautam

Previously unset wrote:

Thanks very much for Gautam’s reply! But I still have two questions.

1. I'm still confused about the unit of the LFP waveform in the *.eeg files. In the "crcns.org hc2 data description" pdf file, it is mentioned that the neurophysiological signals were amplified 1,000x, but you said  the voltage was amplified 20,000x, why?  Additionally, in the 16-bit coded numbers, whether it includes a sign bit?

2. I've comprehended that the spike clusters are unrelated to the number of channels, but I want to know that how a specified cluster is assigned to the corresponding electrode. In the "LoadCluRes" script, it is commented that "Map is a matrix displaying the correspondance between new cluster numbers (first column) and inital shank # (second column) and cluster # (third column)". In the matrix "Map" of "ec013.527", for example, the 9th line is " 9 1 12", what the "12" means? In otheer words, how can I find the spike train of a neuron is recorded by which electrode?

Thamks!

 

 

 

One more thing for #2 - The 3rd column does not indicate which electrodes a cluster was detected on. For this, you need to refer to the file binary file of spike waveshape (FileBase.spk.N), which is described in the documentation as containing the pattern of depolarizations detected across electrodes for each spike.