Memory in hippocampal and cortico-hippocampal circuits

Abstract

The primary objective of the present thesis is to understand the principal computational processes performed by the hippocampus and the surrounding cortex in encoding and retrieval of spatial memory. First, we have shown that memory retention in the water maze depends critically on the integrity of hippocampal area CA3 and that successful retention depends on the integrity of longitudinal impulse transmission in the hippocampus. Second, hippocampal formation contains at least two functionally separable circuits with independent mnemonic capacity where the direct entorhinal– CA1 system is sufficient for recollection–based recognition memory, but recall depends on intact CA3-CA1 connectivity. Third, results from lesions made in the dorsolateral and ventromedial band of the entorhinal cortex point to a modular organization of the entorhinal cortex with an essential role for the dorsolateral band in spatial memory and the ventromedial band in control of defensive behavior.