FIG. 3.
Changes of the hippocampal response as a function of structural properties of cortical network. The hippocampus has one stored memory (neuron IDs 300–400), in the form of 400 additional network connections. (a) Cortex is a homogenous network (i.e., no stored memory). Six neurons in the hippocampus, IDs 315–320, are stimulated with input Istim=4 and show strong activation, whereas the activation of the homogeneous cortex due to input from hippocampus is limited. (b) The cortex has a single network heterogeneity (memory) stored in the form of 400 additional connections. The hippocampus, with the same memory stored, is stimulated by the same input current, and subsequently triggers the cortical memory, which activates strongly and depresses activation of the hippocampus. (c) Mean activation of hippocampal and cortical networks as a function of added connections. As the memory is progressively stored in the cortex (i.e., becomes more familiar), cortical activation increases while hippocampal activation is depressed.