Slide 6

Antidromic Spikes in Cortical Neurons Exhibit a Strong "Kink" at Spike Onset

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Figure 6.  It is well known that antidromic spikes in cortical neurons rise rapidly from the baseline.  Here is shown three antidromic spikes in a cortical pyramidal cell initiated by stimulation of the axon.  The spikes are expanded in the upper left.  Note the two components - the IS or initial segment spike and the SD or somatodendritic spike.  From  Pare, Lang and Destexhe, Neuroscience 84: 377 (1998). 

Importantly, it is well known that cortical neurons initiate spikes in their axons under normal conditions, indicating that spikes recorded in the soma are largely "antidromic" or back-propagating.  (see Stuart et al., TINS 20:125; Palmer and Stuart, J. Neurosci. 26: 1854; Shu et al. J. Neurophysiol. in press.