Using the Change Manager Model for the Hippocampal System to Predict Connectivity and Neurophysiological Parameters in the Perirhinal Cortex

Figure 4

The full hippocampal system model. In addition to the flow of connectivity from across the cortex to the hippocampus proper and back to the cortex, there are a number of subcortical structures that play functional roles. The thalamus has the role of releasing cortical activity between areas by placing gamma band frequency modulations on neuron spike outputs. CA1 drives receptive field expansions on the basis of inputs from CA3. While the competition to select cortical column groups for expansion is under way, the inputs from CA3 do not reflect final selections. CA3 outputs are therefore only released to CA1 when the septal nuclei detect that the competition has concluded. The release is then carried out by imposition of an additional theta band modulation. The mammillary bodies act on the competition process to bias the degree of receptive field expansion in favour of cortical regions that recommend behaviours of the general type that is currently the priority. The amygdala acts on the results of the competition process, to increase the degree of receptive field expansions in more complex cortical areas that record information about the gist of the situation. See Coward [3, 16] for more details.