Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity





The hippocampus receives, via the adjacent parahippocampal gyrus and entorhinal cortex inputs from virtually all association areas in the neocortex, including those in the parietal, temporal, and frontal lobes. (Rolls & Treves; Neural Networks, 107)

The hippocampus has available highly elaborated multimodal information that has already been processed extensively along different, and partially interconnected, sensory pathways. (Rolls & Treves; Neural Networks, 107)

The provision of a single network for association between any subset of neurons (the CA3 neurons) may be an important feature of what the hippocampus circuitry provides for memory. (Rolls & Treves; Neural Networks, 107)

To complement the massively convergent set of pathways into the hippocampus, there is a massively divergent set of backprojecting pathways from the hippocampus via the entorhinal cortex to the cerebral neocortical areas that provide inputs to the hippocampus. (Rolls & Treves; Neural Networks, 108)

Within the hippocampus, information is processed along a mainly unidirectional path, consisting of three major stages. (Rolls & Treves; Neural Networks, 108)

Axonal projections mainly from layer 2 of entorhinal cortex reach the granule cells in the dentate gyrus via the perforant path (PP), and also proceed to make synapses on the apical dendrites of pyramidal cells in the next stage, CA3. (Rolls & Treves; Neural Networks, 108)

A different set of fibers projects from the entorhinal cortex (mainly layer 3) directly onto the third processing stage, CA1. (Rolls & Treves; Neural Networks, 108)

The extrinsic axonal projections from CA3, the Schaffer collaterals, provide the major inputs to CA1 pyramidal cells. (Rolls & Treves; Neural Networks, 110)

Information appears to be funneled from the dentate gyrus (DG) through the CA3 bottleneck, and then spread out again into CA1. The output of CA1 returns directly, and via the subiculum, to the entorhinal cortex, from which it is redistributed to neocortical areas. (Rolls & Treves; Neural Networks, 110)


The anatomical relationships are indicated in a hippocampus diagram.


Rollsís theory of the hippocampus in which the CA3 neurons operate as an autoassociation memory to store episodic memories including object and place memories, and the dentate granule cells operate as a preprocessing stage by performing pattern separation so that the mossy fibers could act to set up different representations for each memory to be stored in the CA3 cells. (Rolls; Memory, Attention, and Decision-Making, 37)



Return to ó Hippocampus

Hippocampus Connections with Neocortex

(Rolls, Neural Networks and Brain Function, 97)