Spike sorting algorithms use the shape(s) of waveforms collected with one or more electrodes in the brain to distinguish the activity of one or more neurons from background electrical noise.
They are thus easily separated by filtering: highpass for spikes and low pass for the synaptic mechanisms.
The synaptic current contributes to the global local field potential (LFP).
These electrodes, positioned outside of the cells in the tissue, however, often 'see' the spikes generated by several neurons in their vicinity.
Recording electrodes can be metal wires or fine print on a PCB with gold or platinum plated at their exposed tips to ensure good contact and prevent change in resistance while the experiment is going on.