Head direction is coded more strongly than movement direction in a population of entorhinal neurons

Florian Raudies, Mark P Brandon, G William Chapman, Michael E Hasselmo

Abstract:

The spatial firing pattern of entorhinal grid cells may be important for navigation. Many
different computational models of grid cell firing use path integration based on movement
direction and the associated movement speed to drive grid cells. However, the response of
neurons to movement direction has rarely been tested, in contrast to multiple studies showing
responses of neurons to head direction. Here, we analyzed the difference between head
direction and movement direction during rat movement and analyzed cells recorded from
entorhinal cortex for their tuning to movement direction. During foraging behavior, movement
direction differs significantly from head direction. The analysis of neuron responses shows that
only 5 out of 758 medial entorhinal cells show significant coding for both movement direction
and head direction when evaluating periods of rat behavior with speeds above 10 cm/s and
7301 angular difference between movement and head direction. None of the cells coded
movement direction alone. In contrast, 21 cells in this population coded only head direction
during behavioral epochs with these constraints, indicating much stronger coding of head
direction in this population. This suggests that the movement direction signal required by most
grid cell models may arise from other brain structures than the medial entorhinal cortex.