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. Author manuscript; available in PMC: 2009 Jan 7.
Published in final edited form as: Trends Neurosci. 2006 Oct 13;29(12):662–670. doi: 10.1016/j.tins.2006.10.002

Figure 3.

Figure 3

Model of CA1 and CA3 transformations of input. Age-related changes are denoted by red dashed lines. The CA1 subregion responds in a linear manner to changes in input. In response to two inputs, CA1 processing of both young and aged individuals generates two outputs whose difference is equal to the difference between the two inputs. The CA3 region responds in a non-linear manner to changes in input. In response to two inputs, CA3 processing of aged individuals generates two outputs whose difference is relatively smaller than that generated by CA3 processing of young individuals. Thus, the CA3 of aged individuals performs excessive pattern completion. In this model, the linear responses of aged CA1, with its greater independence from CA3 (see main text), are not affected by the CA3 deficiencies. Adapted, with permission, from Ref. [28].