Figure 5. Memory Encoding in Hippocampus.

An important issue with respect to the functional significance of hierarchical encoding is whether processing eventually conforms to the overall input-output processing features of the structure involved. This is required otherwise the processed information does not get transmitted to the appropriate effector (i.e. behavioral response) system. The average peak firing rates of cells involved in hierarchical processing in CA3 and CA1 were compared and showed similar firing tendencies in the critical phases of both types of trial, as well as on error trials in which the output structure CA1 showed the same decrease as in CA3 across all task phases. Although there are other reasons why such correspondence in average firing may not occur, such as initiation of the “wrong” code as shown in Figure 4B, the substrates required for successful performance are not possible without ‘consistent utilization’ of the appropriate Conjunctive and TT cells in the CA1output region of hippocampus.