Different coding schemes in dorsal and ventral hippocampus

1
Different coding schemes in dorsal and ventral
hippocampus
Sebastien Royer
Jagdish Patel
2
rodent
primate
cortex
cortex
P
D
V
A
Space representation
Other-than-space representation
3
Extrapolation from existing data
dMEC
Predictiongiant place fields in VH
small
larger
?
Jung et al. Hippocampus (1994)
Hafting et al. Nature 2005
Maurer, Vanrhoads, Sutherland, Lipa, McNaughton,
Hippocampus 2005
Hafting et al. Science 2008
4
water port
7-arm radial
zig-zag maze
open field
5
Absence of place cells in the ventral hippocampus?
Dorsal CA3
1 m
Discrete place fields, high peak firing rates
6
Absence of place cells in the ventral hippocampus?
Field size ( pixels)
area
7
Dorsal CA3 neurons have small, single,
direction-specific place fields (as in
McNaughton, Barnes, OKeefe, Brain Res, 1983)
1
neuron
329
8
Ventral CA3 neurons fire on multiple-arms, in a
direction-specific manner
9
vCA3
10
Ventral CA3 neurons are arm type-specific (only
on reward-bound journeys)
11
Ventral CA3 population increases firing rate on
reward-bound travels
dorsal CA3
12
Ventral CA3 neurons in the zig-zag maze respond
to local geometrical features
dorsal CA3
13
Firing fields of vCA3 neurons are larger and less
directional
right journey
right journey
left journey
14
Firing patterns of vCA3 neurons in the zig-zag
maze reflect distances from the goal
vCA3
L
R
R
L
int
15
Paucity of theta oscillations in ventral
hippocampus
16
Paucity of theta-rhythmic vCA3 neurons
dCA3 pyramidal cells
vCA3 pyramidal cells
1313
162
17
Fewer vCA3 neurons show phase precession
vCA3 pyramidal cells
dCA3 pyramidal cell
18

• Differences between vCA3 and dCA3
• vCA3 neurons fired on multiple arms of the
  radial maze
• firing fields of vCA3 often formed a ring
  (similar mechanisms in each arm)
• vCA3 neurons differentiated between open and
  closed arms in the radial maze.
• Both arm type differentiation and arm segment
  generalization (ring) of v CA3 depended on the
  direction of travel
• vCA3 neurons showed mirror-symmetric firing
  patterns in the zig-zag maze (distance from the
  goal)
• cone-shaped place fields were exceptionally rare
  in vCA3
• LFP theta power in vCA3 was smaller than in dCA3
• Only a small fraction of vCA3 pyramidal cells and
  interneurons showed theta rhythmicity
• Only a small fraction of vCA3 neurons showed
  phase precession

19
HypothesisVentral hippocampus in the rat is
functionally similar to pes and body of the
primate hippocampusDorsal hippocampus may be
functionally similar to the tail
tail
pes/uncus
body
VH
20
CA1
Differential CA3 projections (ventral CA3
strongly projects to granule cells)
mol layer
CA1
mol layer
CA1
Li, Somogyi, Ylinen, Buzsaki, J comp Neurol 1994