This document discusses how head direction cells (HDCs) and grid cells (GCs) in the rat brain may support path integration through their firing patterns. Several findings suggest that HDC firing reflects angular path integration, maintaining directional firing after manipulations and depending on self-motion cues. Evidence also indicates that GC firing reflects translational path integration, preserving grid patterns across environments and rescaling grids relative to boundaries. The document concludes that HDC and GC firing patterns integrate self-motion and environmental information to reduce errors in estimating self-location.

1. How Environment and Self-motion Combine
in Neural Representations of Space
Evans. T et al
2015
J Physiol

2. Navigation
▪ Navigation based on environmental sensory input is crucial
behavior to the survival in an environment
latitude
longitude

3. Spatial Information Processing Neurons
▪ Rat has the navigation neurons that represent the place[1],
grid[2], boundary[3] and direction[4] information in the
environment
[1] O’keefe and Dostrovsky, 1971, Brain Res [3] Lever et al., 2009, J Neurosci. [5] Moser et al., 2008, Annu Rev Neurosci
[2] Fyhn et al., 2004, Science [4] Taube et al., 1990, J Neurosci. [6] Zhang et al., 2013, Philos Trans R Soc Lond B Biol Sci.
Place cell
[5]
Head direction (°)
Firingrate(Hz)
Preferred direction
Head direction cell
[4]
Boundary vector cell
[7]
[5]
Rat trajectory
Cell spikes
Grid cell

4. Boundary Vector Cell
▪ Boundary Vector Cells (BVCs) of subiculum process boundary
information in the environment [1]
[7]
[8]
Hippocampus
Receptive field Firing rate
[11]
Firing rate mapFreely moving rat
BVC’s spikes
[9]
[10]
BVC’s spikes
Rat’s trajectory
Hippocampal formation Receptive field Firing field
Subiculum
[7] Bannerman et al., 2014 [8] Drexel et al., 2013 [9] Hartley et al., 2000 [10] Lever et al., 2009 [11] Zhang et al., 2014

5. Head Direction Cell
▪ Head direction cells (HDCs) discharged as a function of the
animal’s allocentric head direction in the horizontal plane
Firing pattern
Firing rate
[13]
HDC’s spikes
Rat’s trajectory
Hippocampal formation Head direction Firing field
[12] Ding et al., 2013, J of Comparative Neurology [13] Tang et al., 2016
Subiculum
Hippocampus
Postsubiculum
[12]
Firing rate

6. Grid Cell
▪ Grid cell (GC) shows increased firing rate at multiple locations,
regularly positioned in a grid across the environment consisting of
equilateral triangles
Medial entorhinal cortex Spike response
[14] McNaughton et al., 2006, Nature Review [15] Moser and Moser, 2010, Moser group
Postrhinal cortex
Medial
entorhinal
cortex
[15]
[14]

7. Place Cell
▪ Place cell in hippocampal CA1 fires at specific one location
Hippocampal CA1 Spike response
[18] Nakazawa et al., 2004, Nature Reviews [19] 2014 Phillip Sharp Lecture in Neural Circuits Dr. May-Britt
[18]
[19]

8. Research Question
▪ The path integration is crucial navigation task for homing with the
shortest path
▪ The path integration sums the vectors of distance and direction
travelled from a start point to current position
Path integration based on
homing vector
Vector integration

9. Research Question
▪ How path integration is processed by spatial information processing
cells?
Path integration model based on GC and HDC
[18] McNaughton et al., 2006, Nature reviews

10. Head Direction Cell for Path Integration
▪ Several findings support the hypothesis that HDC firing patterns
reflect angular path integration
▫ HDCs maintain coherent firing pattern after environmental manipulations
initial
90 ° rotate
return
1
2
3
[19] Taube, 1990, J Neurosci. [20] Mizumori & Williams, 1993, J Neurosci

11. Head Direction Cell for Path Integration
▪ Several findings support the hypothesis that HDC firing patterns
reflect angular path integration
▫ HDC firing patterns are strongly dependent on self-motion inputs from the
vestibular system
[19] Jacob et al., 2014, Front. Integr Neurosci. [20] Stackman & Taube, 2006, J Neurosci.
PPTN: pedunculopontine nucleus; SMN: supramammilary nucleus;
DTN: dorsal tegmental nucleus; LMN: lateral mammilary nucleus;
ATN: anterodorsal thalamic nucleus.
HDC with ATN legion

12. Head Direction Cell for Path Integration
▪ Several findings support the hypothesis that HDC firing patterns
reflect angular path integration
▫ Shifts in the preferred firing direction (PFD) of HDCs correlate with angular
error in the homing trajectory
[19] Valerio & Taube, 2012, Nature

13. Grid Cell for Path Integration
▪ The multiple firing field of GC might track the movement of the
animal
▪ Also, there are some evidence that the firing patterns of GC reflect
translational path integration
▫ GCs maintain coherent firing pattern after environmental manipulations
[20] Hafting et al., 2005

14. Grid Cell for Path Integration
▪ There are some evidence that the firing patterns of GC reflect
translational path integration
▫ While PCs undergo re-mapping between different environments, GCs
preserve their firing patterns across all environments
[20] Stensola et al., 2012
Global re-mapping in PC Grid structure of GC in novel place

15. Grid Cell for Path Integration
▪ There are some evidence that the firing patterns of GC reflect
translational path integration
▫ The firing field of neighboring GCs share a similar scale and orientation
form cohesive functional modules
[20] Stensola et al., 2012

16. Grid Cell for Path Integration
▪ There are some evidence that the firing patterns of GC reflect
translational path integration
▫ The scale of grid firing patterns relative to the boundaries of a square
environment
[20] Barry et al., 2007, Nature Neurosci. [21] Hafting et al., 2005, Nature
Re-scaling of GC firing

17. Conclusion
▪ The evidences that the firing patterns of HDCs and GCs reflect
angular and translational path integration
▫ HDC and GC is initialized their firing pattern based on environmental
cues
▫ The firing pattern of HDC and GC reflect the self-motion and
environmental sensory information

18. Discussion
▪ The spatial information processing cells receive the environmental
sensory inputs that needs to reduce errors in estimates of self-
location for path integration
Idiothetic input
Visual area 17
Visual stream
Restosplenial cortex

19. Stable Firing of GC
▪ The BVC input from subiculum might help for stable GC firing
pattern
1.5 m * 1.5 m, 587 GCs 1.5 m * 1.5 m, 220 GCs