Neuroanatomical Pathways for Learning and Memory Consolidation

Insausti, R. , Muñoz, M. , Legidos García, E. , Mohedano-Moriano, A. , Artacho Pérula, E. , Arroyo Jiménez, M. d. M. , Marcos Rabal, P. & Iñiguez de Onzoño, M.

Human Neuroanatomy Laboratory, UCLM

The Hippocampal Formation (HF) is crucial for learning and memory. Experimental and clinical lesion studies show that the HF is not a repository for memories. The hippocampal formation (HF), which includes several hippocampal fields plus the entorhinal cortex (EC), is the key player in learning and memory. It is hypothesized that memory consolidation needs, first to be processed by the HF, and second, to send the projections back to the neocortex. We present anatomical data in the nonhuman primate on return projections to the neocortex which may underlie learning and memory consolidation. Afferents to the HF are directed to the EC (polymodal association cortices of the parahippocampal region). Polymodal information is thus collected and relayed to the DG, and after a unidirectional route, ends in the deep layers (V and VI) of the EC, which also receive amygdaloid input. Layers V and VI of the EC do project back to the same visual auditory and somatosensory related neocortical regions. Interestingly, the lateral prefrontal cortex lacks afferent or efferent projections with the EC. Our data support a multisynaptic network from the EC to the neocortex supporting learning and memory consolidation. Supported by BFU 2006 12964 and BFU 2009-14705