Different coding schemes in dorsal and ventral hippocampus

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Different coding schemes in dorsal and ventral hippocampus Sebastien Royer Jagdish Patel

Different coding schemes in dorsal and ventral hippocampus Sebastien Royer Jagdish Patel

rodent primate cortex D V A Space representation Other-than-space representation P

rodent primate cortex D V A Space representation Other-than-space representation P

Extrapolation from existing data d. MEC Prediction: giant place fields in VH small larger

Extrapolation from existing data d. MEC Prediction: giant place fields in VH small larger ? ? ? Jung et al. Hippocampus (1994) Hafting et al. Nature 2005 Maurer, Vanrhoads, Sutherland, Lipa, Mc. Naughton, Hippocampus 2005 Hafting et al. Science 2008

water port open field 7 -arm radial zig-zag maze

water port open field 7 -arm radial zig-zag maze

Absence of place cells in the ventral hippocampus? Dorsal CA 3 Ventral CA 3

Absence of place cells in the ventral hippocampus? Dorsal CA 3 Ventral CA 3 1 m Discrete place fields, high peak firing rates Large, diffuse or multiple peak firing fields, low peak firing rates

Absence of place cells in the ventral hippocampus? Field size (# pixels) % area

Absence of place cells in the ventral hippocampus? Field size (# pixels) % area Field size (contour) % area spatial information stability (R: first half/second half) bits

Dorsal CA 3 neurons have small, single, direction -specific place fields (as in Mc.

Dorsal CA 3 neurons have small, single, direction -specific place fields (as in Mc. Naughton, Barnes, O’Keefe, Brain Res, 1983) n e u r o n # 1 329

Ventral CA 3 neurons fire on multiple-arms, in a direction-specific manner

Ventral CA 3 neurons fire on multiple-arms, in a direction-specific manner

v. CA 3 neurons fire on multiplearms % of arms # of active arms

v. CA 3 neurons fire on multiplearms % of arms # of active arms v. CA 3 neurons are more direction -specific than d. CA 3 % of cells v. CA 3 r

Ventral CA 3 neurons are arm type-specific (only on reward-bound journeys)

Ventral CA 3 neurons are arm type-specific (only on reward-bound journeys)

Ventral CA 3 population increases firing rate on reward-bound travels dorsal CA 3 ventral

Ventral CA 3 population increases firing rate on reward-bound travels dorsal CA 3 ventral CA 3

3 dorsal CA 3 Ventral CA 3 neurons in the zig-zag maze respond to

3 dorsal CA 3 Ventral CA 3 neurons in the zig-zag maze respond to local geometrical features

right journey Firing fields of v. CA 3 neurons are larger and less directional

right journey Firing fields of v. CA 3 neurons are larger and less directional left journey

Firing patterns of v. CA 3 neurons in the zig-zag maze reflect distances from

Firing patterns of v. CA 3 neurons in the zig-zag maze reflect distances from the goal v. CA 3 R L int

Paucity of theta oscillations in ventral hippocampus

Paucity of theta oscillations in ventral hippocampus

Paucity of theta-rhythmic v. CA 3 neurons d. CA 3 pyramidal cells 1313 v.

Paucity of theta-rhythmic v. CA 3 neurons d. CA 3 pyramidal cells 1313 v. CA 3 pyramidal cells 162 d. CA 3 interneurons 107 v. CA 3 interneurons 35

Fewer v. CA 3 neurons show phase precession v. CA 3 pyramidal cells d.

Fewer v. CA 3 neurons show phase precession v. CA 3 pyramidal cells d. CA 3 pyramidal cell

Differences between v. CA 3 and d. CA 3 • v. CA 3 neurons

Differences between v. CA 3 and d. CA 3 • v. CA 3 neurons fired on multiple arms of the radial maze • firing fields of v. CA 3 often formed a ring (similar mechanisms in each arm) • v. CA 3 neurons differentiated between open and closed arms in the radial maze. • Both arm type differentiation and arm segment generalization (ring) of v CA 3 depended on the direction of travel • v. CA 3 neurons showed mirror-symmetric firing patterns in the zig-zag maze (distance from the goal) • cone-shaped place fields were exceptionally rare in v. CA 3 • LFP theta power in v. CA 3 was smaller than in d. CA 3 • Only a small fraction of v. CA 3 pyramidal cells and interneurons showed theta rhythmicity • Only a small fraction of v. CA 3 neurons showed phase precession

Hypothesis: Ventral hippocampus in the rat is functionally similar to pes and body of

Hypothesis: Ventral hippocampus in the rat is functionally similar to pes and body of the primate hippocampus Dorsal hippocampus may be functionally similar to the tail pes/uncus body VH

CA 1 mol layer CA 1 Li, Somogyi, Ylinen, Buzsaki, J comp Neurol 1994

CA 1 mol layer CA 1 Li, Somogyi, Ylinen, Buzsaki, J comp Neurol 1994 Differential CA 3 projections (ventral CA 3 strongly projects to granule cells)