Slide 9

The "DOWN" state is associated with a slow afterhyperpolarization and a relative refractory period for generating persistent activity

Figure 9.  Activation of persistent activity with the local application of a pulse of glutamate at varying times from a previous pulse of glutamate revealed a relative refractory period for the "UP" state (A).  This refractory period lasts for approximately 5 seconds.  B.  In many cortical pyramidal cells, the "DOWN" state is associated with the generation of a slow afterhyperpolarization (AHP) (b1).  This ahp reduces the excitability of the neuron and suppresses its response to the intracellular injection of a depolarizing current pulse (b2).