Hippocampal formation plays a prominent role in episodic memory formation and consolidation. It is likely that episodic memory representations are constructed from cortical information that is mostly funnelled through the entorhinal cortex to the hippocampus. The entorhinal cortex returns processed information to the neocortex. Retrograde tracing studies have shown that neocortical afferents to the entorhinal cortex originate almost exclusively in polymodal association cortical areas. However, the use of retrograde studies does not address the question of the laminar and topographical distribution of cortical projections within the entorhinal cortex. We examined material from 60 Macaca fascicularis monkeys in which cortical deposits of either ³H‐amino acids or biotinylated dextran‐amine as anterograde tracers were made into different cortical areas (the frontal, cingulate, temporal and parietal cortices). The various cortical inputs to the entorhinal cortex present a heterogeneous topographical distribution. Some projections terminate throughout the entorhinal cortex (afferents from medial area 13 and posterior parahippocampal cortex), while others have more limited termination, with emphasis either rostrally (lateral orbitofrontal cortex, agranular insular cortex, anterior cingulate cortex, perirhinal cortex, unimodal visual association cortex), intermediate (upper bank of the superior temporal sulcus, unimodal auditory association cortex) or caudally (parietal and retrosplenial cortices). Many of these inputs overlap, particularly within the rostrolateral portion of the entorhinal cortex. Some projections were directed mainly to superficial layers (I–III) while others were heavier to deep layers (V–VI) although areas of dense projections typically spanned all layers. A primary report will provide a detailed analysis of the regional and laminar organization of these projections. Here we provide a general overview of these projections in relation to the known neuroanatomy of the entorhinal cortex.

Our current understanding of the spread and neurodegenerative effects of tau neurofibrillary tangles (NFTs) within the medial temporal lobe (MTL) during the early stages of Alzheimer’s Disease (AD) is limited by the presence of confounding non-AD pathologies and the two-dimensional (2-D) nature of conventional histology studies. Here, we combine ex vivo MRI and serial histological imaging from 25 human MTL specimens to present a detailed, 3-D characterization of quantitative NFT burden measures in the space of a high-resolution, ex vivo atlas with cytoarchitecturally-defined subregion labels, that can be used to inform future in vivo neuroimaging studies. Average maps show a clear anterior to poster gradient in NFT distribution and a precise, spatial pattern with highest levels of NFTs found not just within the transentorhinal region but also the cornu ammonis (CA1) subfield. Additionally, we identify granular MTL regions where measures of neurodegeneration are likely to be linked to NFTs specifically, and thus potentially more sensitive as early AD biomarkers.

Obesity/overweight are important health problems due to metabolic complications. Dysregulation of peptides exerting orexigenic/anorexigenic effects must be investigated in-depth to understand the mechanisms involved in feeding behaviour. One of the most important and studied orexigenic peptides is galanin (GAL). The aim of this review is to update the mechanisms of action and physiological roles played by the GAL family of peptides (GAL, GAL-like peptide, GAL message-associated peptide, alarin) in the control of food intake and to review the involvement of these peptides in metabolic diseases and food intake disorders in experimental animal models and humans. The interaction between GAL and NPY in feeding and energy metabolism, the relationships between GAL and other substances involved in food intake mechanisms, the potential pharmacological strategies to treat food intake disorders and obesity and the possible clinical applications will be mentioned and discussed. Some research lines are suggested to be developed in the future, such as studies focused on GAL receptor/neuropeptide Y Y₁ receptor interactions in hypothalamic and extra-hypothalamic nuclei and sexual differences regarding the expression of GAL in feeding behaviour. It is also important to study the possible GAL resistance in obese individuals to better understand the molecular mechanisms by which GAL regulates insulin/glucose metabolism. GAL does not exert a pivotal role in weight regulation and food intake, but this role is crucial in fat intake and also exerts an important action by regulating the activity of other key compounds under conditions of stress/altered diet.