The is an important
Memory center in the
Brain . The EC forms the main input to the
Hippocampus and is responsible for the pre-processing (familiarity) of the input signals. In the reflex
Nictitating Membrane response of classical trace conditioning, the association of impulses from the
Eye and the
Ear occurs in the entorhinal cortex. The
EC-hippocampus System plays an important role in
Memory Consolidation and
Memory Optimization in
Sleep .
Entorhinal cortex is one of the first areas to be affected in Alzheimer's Disease, and one of the first symptoms are impaired sense of direction. In 2005, it was discovered that entorhinal cortex contains a neural map of the spatial environment.
1
The entorhinal cortex show a modular organization, with different properties and connections in different areas.
Neurons in the lateral entorhinal cortex exhibit little spatial selectivity
2 while neurons of the medial entorhinal (MEA) cortex exhibit multiple "place fields" that are arranged in an hexagonal pattern, and are therefore called "
Grid Cells ". These fields and spacing between fields increase from the dorso-lateral MEA to the ventro-medial MEA.
3
In rodents, EC is located at the
Caudal end of the
Temporal Lobe and is usually divided into
Medial and
Lateral regions (with three bands with distinct properties and connectivity running perpendicular across the whole area). A distinguishing characteristic of EC is the lack of cell bodies where layer IV should be; this layer is called the ''lamina dissecans''.
The superficial layers - layers II and III - of EC project to the and hippocampal region CA3; layer III primarily projects to hippocampal region CA1 and the
Subiculum . These layers receive input from other cortical areas, especially associational, perirhinal, and parahippocampal cortices, as well as
Prefrontal Cortex . EC as a whole, therefore, receives highly-processed input from every sensory modality, as well as input relating to ongoing cognitive processes, though it should be stressed that, within EC, this information remains at least partially segregated.
The deep layers, especially layer V, receive one of the three main outputs of the
Hippocampus and, in turn, reciprocate connections from other cortical areas that project to superficial EC.
