Educational Course - Full Day (8 hours)
This lecture will review the structural and functional divisions in the medial temporal lobe, with a special focus on the hippocampus. The hippocampus is a critical region of the brain for the formation of new episodic memories. It is also a region that is vulnerable to a number of developmental, psychiatric, and neurological conditions. It is one of the most well-studied regions of the brain.
It is important to note that the hippocampus is not a singular homogeneous structure, but is a layered structure that is commonly divided into distinct subfields. Similarly, the medial temporal lobe cortex, the region of cortex just lateral to the hippocampus, is composed of the entorhinal and perirhinal cortices, anteriorly, and the parahippocampal cortex, posteriorly. Different neuroanatomists have used slightly different nomenclature to subdivide the hippocampus over the years to define these subregions. This lecture will provide a comprehensive overview of the historical developments that have led to the current definitions of the universally recognized hippocampal subfields, which include the dentate gyrus, the cornu ammonis (CA) regions 1-4, and the subiculum. I will also provide definitions of the less commonly recognized regions. For example, the transition region between CA1 and subiculum is sometimes defined as the prosubiculum and the pre- and para-subiculum regions are regions that are sometimes identified in between the subiculum and the entorhinal cortex.
I will discuss how the subfields of the hippocampus differ from one another and how they are defined anatomically. I will discuss the functional differences between these regions of the brain and how they contribute to different types of cognitive functions. I will also discuss how these regions of the brain change with advanced age and cognitive decline.
Finally, I will discuss common neuroimaging methodology to define the medial temporal lobe regions using different types of structural (e.g. T1-weighted and T2-weighted) magnetic resonance imaging (MRI). Finally, I will discuss challenges and solutions for the study of the hippocampal and MTL cortex subregions using in vivo MRI.
References:
Olsen, R. K., Carr, V. A., Daugherty, A. M., La Joie, R., Amaral, R. S., Amunts, K., ... & Hippocampal Subfields Group. (2019). Progress update from the hippocampal subfields group. Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring, 11(1), 439-449.
MazloumâFarzaghi, N., Barense, M. D., Ryan, J. D., Stark, C. E. L., & Olsen, R. K. (2024). The Effect of Segmentation Method on Medial Temporal Lobe Subregion Volumes in Aging. Human Brain Mapping, 45(15), e70054.
Baumeister, H., Wuestefeld, A., Adams, J. N., Bakker, A., Daugherty, A. M., de Flores, R., ... & Wisse, L. E. (2023). Comparison of histological delineation of the entorhinal, perirhinal, ectorhinal, and parahippocampal cortices by different neuroanatomy laboratories. Alzheimer's & Dementia, 19, e076135.