Linking Cellular Mechanisms to Behavior: Entorhinal Persistent Spiking and Membrane Potential Oscillations May Underlie Path Integration, Grid Cell Firing, and Episodic Memory
Figure 6
Model of episodic encoding
and retrieval of trajectories. Top:
Schematic representation of connectivity between grid cells, place cells, and
head direction (HD) cells. Bottom: example
of trajectory retrieval activity in each region. Trajectory experienced during encoding is
shown in gray. (a) The location coded by
the oscillation phase of entorhinal grid cell membrane potential is plotted as
a dashed line that follows the actual trajectory in gray. Grid cell phase is put through the inverse
head direction transformation to obtain coded location. Phase shifts are driven by retrieved head
direction until next place cell is activated, then phase moves in new direction
dependent on next active head direction cell.
(b) Sequentially activated place cell representations are shown as open
circles. (c) Each place cell activates a
corresponding head direction representation, with direction shown as a short,
straight, black line. This drives the
next period of update of the grid cell phase.