Okay, Jupyter is apparently is not working, so I can't use matlab code. So I'll just put it here. A brief description follows.

First take a look at 4shanks_plot_layout.png.

4shanks_plot_layout.mat contains a fieldtrip-style 'lay' structure. This structure is helpful in plotting the individual electrodes in their spatial organization. That is, it can be used to plot each electrode in a nice spatial configuration with shank electrode outlines surrounding them. Much more robust than using subplots, and using the syntax far below you have more direct control of how your small plots look.

The structure contains:

lay =

    pos: [34x2 double]
  label: {34x1 cell}
  width: [34x1 double]
 height: [34x1 double]
   mask: {[5x2 double]  [5x2 double]  [5x2 double]  [5x2 double]}
outline: {[6x2 double]  [6x2 double]  [6x2 double]  [6x2 double]}
    cfg: [1x1 struct]

lay.pos = contains x and y coordinates for the center of each electrode
lay.label = channel indentier of the form 'chanXX', where XX is the index of the electrode in the original matfiles
lay.width = width of the axes box
lay.height = height of the axes box
lay.mask = cell-array containing masking boxes. These areas can be used to interpolation, to plot data in a similar way as scalp topographies for EEG. (not super useful for the HC data, but included them anyway)
lay.outline = cell-array with the outline coordinates of each shank
lay.cfg = ignore this, fieldtrip-style bookkeeping

You'll notice there are 34 electrodes in there. The additional two (the last ones) are used by fieldtrip functions to plot additional info.

How to use it

The goal is to do:

axes('position',[left bottom width height])

This creates a local axes system to plot electrode specific stuff in. To get there using the x and y coordinates need to be converted to 'left' and 'bottom' (there are reasons why this isn't done by default).

For any channel with index 'ind', the [left bottom width height] will be:
[lay.pos(ind,1) - (lay.width(ind)/2) ...
lay.pos(ind,2) - (lay.height(ind)/2) ...
lay.width(ind) ...
lay.height(ind)]

The outlines of the shanks can be plotted using 'line' something like:
xline = outline{ioutline}(:,1);
yline = outline{ioutline}(:,2);
line(xline,yline,'linewidth',3)