FIGURE 5.

A-B. Neurons with resonance properties can interact in oscillatory attractor dynamics to generate coding of spatial location by relative phase similar to the OIM. A. The circuit involves a population of resonant stellate cells with excitatory connections with pyramidal cells (Pyr Cells) that receive phase-specific oscillatory input from medial septal neurons (Med Septum). B. Stellate cell numbers S1-S3 start out active and then show rebound activity that activates pyramidal cells P1-P4 according to the phase of Medial Septum (MS) input to pyramidal cells, and engages excitatory feedback between the stellates and pyramidals. Stellate cells rebound slightly faster than the frequency of MS input, activating pyramidal cells at earlier phases, causing a progressive shift in attractor dynamics to different populations. C-E. A similar model uses resonance to generate the theta cycle skipping properties of entorhinal neurons. A set of five stellate cells (C) respond to a hyperpolarizing pulse with rebound spikes (Ca) that excites a set of pyramidal cells (D) causing spiking (Db) that activates a set of inhibitory interneurons (E). The spiking of the interneurons (Ec) causes hyperpolarization in another set of stellate cells to cause rebound spiking (Cd) that induces spiking in a different group of pyramidal cells (De) and interneurons (Ef). These interneurons cause inhibition that induces rebound spiking in the first set of stellate cells (Cg) to start the cycle again. The firing on alternate cycles of theta rhythm resembles theta cycle skipping observed in unit recording from entorhinal cortex (Deshmukh et al., 2010; Brandon et al., 2013).