Local field potential
<p>Sep 28, 2010 12:50 PM
 
low impedance just means low resistance  .
note this is an EXTRACELLULAR signal recorded by a microelectrode:
one electrode in the ECF adjacent to neurons the other is "miles away" in the fluid.
 
The signal is CUT OFF at 300 hz using a low pass filter ... that removes all the spiking (spikes are prob
abt  1000 hz = 1 msec).
 
The electrode measures slower ionic currents from .5 mm to 3 mm from the tip.
 
LFP is the sum of all local currents measured at the surface of the electrode.
 
LFP is believed to repres the synchronized INPUT into the observed area (as opposed to spike data which
is the OUTPUT of neuron's axons.   So LFP is a more sustained current typical of
somato-dendritic currents.
The major slow current is the PSP  (postsynaptic potneital)  both  EPSPSs and IPSPs.</p>