The hippocampal formation (upper panel, adapted from Schultz et al., 1998): The entorhinal cortex (EC), modeled as black box columns, sends perforant pathway fibres (PP) to the dentate gyrus (DG) and to CA3. DG granule cells output mossy fibres (MF) to CA3. CA3 pyramidal cells send axons recurrently into CA3 and to CA1 through the Schaffer collaterals (SC). CA1 pyramidal cells project back to EC (and to the subicular complex, not modeled). Principal cells of DG, CA3 and CA1 also receive cholinergic input from the medial septal complex (not modeled) via the septo-hippocampal pathway (SHP), modeled as a synchronous input. All the cells and the connections within DG, CA3 and CA1 will be modeled in detail (lower panel): the flat scheme of the hippocampus shows the different layers. The DG is divided into hilus/polymorphic layer (H), granule cell layer (G), and molecular layer/fascia dentata (M), which contains the granule cell dendrites. The CA fields are divided into lacunosum layer/stratutm radiatum (L), which contains the pyramidal cell basal dendrites, pyramidal cell layer, and alveus/stratum radiatum (A), which contains the pyramidal cell apical dendrites. The neurons that will be modeled, specified in each layer of the bottom panel, are reported below (each hyperlinked to its synaptic matrix), along with the estimated number of cells (Patton and McNaughton, 1995; Bernard and Wheal, 1994).
Dentate Gyrus (DG): CA3: CA1:
106 gc (granule
cells)
2x105 pc (ca3 pyramidal cells)
3x105 pc (ca1 pyramidal)
3x104 mc (mossy cells)
4x103 ri (radiatum interneurons)
4x103 bc (ca1 basket)
1.5x104 gpc (gabaergic polymorphic
cells) 4x103
oi (oriens interneurons)
4x103 lm (lacunoso-moleculare)
104 bc (dg basket cells)
103 cc (ca3 chandelier cells)
4x103 oa (oriens-alveus)
104 mopp (molecular layer perforant
path cells)
103 cc (ca1 chandelier)
103 cc (dg axoaxonic chandelier
cells)