Abstract
This dissertation used multiple techniques and approaches to understand the neurobiology of perirhinal cortex (PR) during development, adulthood, and aging. A Golgi-Cox study shows this region develops in accordance with general cortical developmental laws. The proportion of pyramidal neurons in PR ( similar to 50%) was notably smaller than reported in neocortical regions. The frequency distribution of cell types results in an overall impression of considerable morphological diversity in PR. Single-unit recordings showed that a large proportion of individual PR neurons ( similar to 30%) were responsive to both auditory and somatosensory stimuli prior to fear conditioning and that conditioning caused changes in the firing patterns of an even larger proportion ( similar to 70%). Some of the changes in firing patterns suggested temporal encoding of the seconds-long interval between the conditional and unconditional stimuli. Aging was associated with a selective and layer-specific decrease in certain calcium-binding proteins.