Recent advances in MRI and increasing knowledge on the characterization and anatomical variability of medial temporal lobe (MTL) anatomy have paved the way for more specific subdivisions of the MTL in humans. In addition, recent studies suggest that early changes in many neurodegenerative and neuropsychiatric diseases are better detected in smaller subregions of the MTL rather than with whole structure analyses. Here, we developed a new protocol using 7 Tesla (T) MRI incorporating novel anatomical findings for the manual segmentation of entorhinal cortex (ErC), perirhinal cortex (PrC; divided into area 35 and 36), parahippocampal cortex (PhC), and hippocampus; which includes the subfields subiculum (Sub), CA1, CA2, as well as CA3 and dentate gyrus (DG) which are separated by the endfolial pathway covering most of the long axis of the hippocampus. We provide detailed instructions alongside slice-by-slice segmentations to ease learning for the untrained but also more experienced raters. Twenty-two subjects were scanned (19–32 yrs, mean age = 26 years, 12 females) with a turbo spin echo (TSE) T2-weighted MRI sequence with high-resolution oblique coronal slices oriented orthogonal to the long axis of the hippocampus (in-plane resolution 0.44 × 0.44 mm2) and 1.0 mm slice thickness. The scans were manually delineated by two experienced raters, to assess intra- and inter-rater reliability. The Dice Similarity Index (DSI) was above 0.78 for all regions and the Intraclass Correlation Coefficients (ICC) were between 0.76 to 0.99 both for intra- and inter-rater reliability. In conclusion, this study presents a fine-grained and comprehensive segmentation protocol for MTL structures at 7 T MRI that closely follows recent knowledge from anatomical studies. More specific subdivisions (e.g. area 35 and 36 in PrC, and the separation of DG and CA3) may pave the way for more precise delineations thereby enabling the detection of early volumetric changes in dementia and neuropsychiatric diseases.

Episodic memory provides us with the ability to re-experience unique events in rich detail. For this to occur, we must be able to 1) behaviorally "pattern separate" or discriminate new from old experiences, and 2) "pattern complete" or reinstate memories from partial cues. I report a rare individual with a specific lesion to the dentate gyrus of his hippocampus who has difficulty distinguishing between studied targets and unstudied lures that are visually similar. In addition, he displays a heightened tendency to recognize studied scenes from degraded pictures. These results provide the first direct evidence in humans that discriminating new memories cannot wholly function without an intact dentate gyrus and that this mnemonic ability is dissociable from, but likely interacts with, completion processes in the CA3 subfield of the hippocampus.iii Acknowledgements

Even though disgust and fear are both negative emotions, they are characterized by different physiology and action tendencies. The aim of this study was to examine whether fear- and disgust-evoking images would produce different attention bias effects, specifically those related to attention (dis)engagement. Participants were asked to identify a target which was briefly presented around a central image cue, which could either be disgusting, frightening, or neutral. The interval between cue onset and target presentation varied within blocks (200, 500, 800, 1100 ms), allowing us to investigate the time course of attention engagement. Accuracy was lower and reaction times were longer when targets quickly (200 ms) followed disgust-evoking images than when they followed neutral- or fear-evoking images. For the other, longer interval conditions no significant image effects were found. These results suggest that emotion-specific attention effects can be found at very early visual processing stages and that only disgust-evoking images, and not fear-evoking ones, keep hold of our attention for longer. We speculate that this increase in early attention allocation is related to the need to perform a more comprehensive risk-assessment of the disgust-evoking images. The outcomes underline not only the importance of examining the time course of emotion induced attention effects but also the need to look beyond the dimensions of valence and arousal.

Accurate memory retrieval from partial or degraded input requires the reactivation of memory traces, a hippocampal mechanism termed pattern completion. Age-related changes in hippocampal integrity have been hypothesized to shift the balance of memory processes in favor of the retrieval of already stored information (pattern completion), to the detriment of encoding new events (pattern separation). Using a novel behavioral paradigm, we investigated the impact of cognitive aging (1) on recognition performance across different levels of stimulus completeness, and (2) on potential response biases. Participants were required to identify previously learned scenes among new ones. Additionally, all stimuli were presented in gradually masked versions to alter stimulus completeness. Both young and older adults performed increasingly poorly as the scenes became less complete, and this decline in performance was more pronounced in elderly participants indicative of a pattern completion deficit. Intriguingly, when novel scenes were shown, only the older adults showed an increased tendency to identify these as familiar scenes. In line with theoretical models, we argue that this reflects an age-related bias towards pattern completion.