CORTICO-HIPPOCAMPAL REPRESENTATIONS IN SIMULTANEOUS ODOR DISCRIMINATION - A COMPUTATIONAL INTERPRETATION OF EICHENBAUM, MATHEWS, AND COHEN (1989)

A previous model of hippocampal region function in classical condition ing is generalized to H. Eichenbaum, A. Fagan, P. Mathews, and N. J. C ohen's (1989) and H. Eichenbaum, A. Fagan, and N. J. Cohen's (1989) si multaneous odor discrimination studies in rats. The model assumes that the hippocampal region forms new stimulus representations that compre ss redundant information while differentiating predictive information; the piriform (olfactory) cortex meanwhile clusters similar and co-occ urring odors. Hippocampal damage interrupts the ability to differentia te odor representations, while leaving piriform-mediated odor clusteri ng unchecked. The result is a net tendency to overcompress in the lesi oned model. Behavior in the model is very similar to that of the rats, including lesion deficits, facilitation of successively learned tasks , and transfer performance. The computational mechanisms underlying mo del performance are consistent with the qualitative interpretations su ggested by Eichenbaum et al. to explain their empirical data.