FIGURE 5.

Model for the pharmacological separation of putative axonal activity from somatic activity using the GABA_A agonist Muscimol. As axons tend to have a sparse density of GABA_A receptors, axonal activity should not be inactivated by local injections of Muscimol. We record somatic action potentials and SDWs simultaneously on the same tetrode (A). Somatic action potentials are inactivated over time as Muscimol diffuses through the hippocampus (B). If SDWs are truly representative of action potential propagation along axons (example SDW shown in blue), then Muscimol should inactivate local somatic activity when it diffuses to the recording site (example pyramidal waveform shown in red) while local SDW activity should persist (B) until sufficient diffusion time has elapsed for Muscimol to inactivate the distal somatic source of the axonal action potential (C).