The impact of ageing reveals distinct roles for human dentate gyrus and CA3 in pattern separation and object recognition memory

© 2017 The Author(s). Both recognition of familiar objects and pattern separation, a process that orthogonalises overlapping events, are critical for effective memory. Evidence is emerging that human pattern separation requires dentate gyrus. Dentate gyrus is intimately connected to CA3 where, in animals, an autoassociative network enables recall of complete memories to underpin object/event recognition. Despite huge motivation to treat age-related human memory disorders, interaction between human CA3 and dentate subfields is difficult to investigate due to small size and proximity. We tested the hypothesis that human dentate gyrus is critical for pattern separation, whereas, CA3 underpins identical object recognition. Using 3 T MR hippocampal subfield volumetry combined with a behavioural pattern separation task, we demonstrate that dentate gyrus volume predicts accuracy and response time during behavioural pattern separation whereas CA3 predicts performance in object recognition memory. Critically, human dentate gyrus volume decreases with age whereas CA3 volume is age-independent. Further, decreased dentate gyrus volume, and no other subfield volume, mediates adverse effects of aging on memory. Thus, we demonstrate distinct roles for CA3 and dentate gyrus in human memory and uncover the variegated effects of human ageing across hippocampal regions. Accurate pinpointing of focal memory-related deficits will allow future targeted treatment for memory loss

Hippocampal - diencephalic - cingulate networks for memory and emotion: An anatomical guide

This review brings together current knowledge from tract tracing studies to update and reconsider those limbic connections initially highlighted by Papez for their presumed role in emotion. These connections link hippocampal and parahippocampal regions with the mammillary bodies, the anterior thalamic nuclei, and the cingulate gyrus, all structures now strongly implicated in memory functions. An additional goal of this review is to describe the routes taken by the various connections within this network. The original descriptions of these limbic connections saw their interconnecting pathways forming a serial circuit that began and finished in the hippocampal formation. It is now clear that with the exception of the mammillary bodies, these various sites are multiply interconnected with each other, including many reciprocal connections. In addition, these same connections are topographically organised, creating further subsystems. This complex pattern of connectivity helps explain the difficulty of interpreting the functional outcome of damage to any individual site within the network. For these same reasons, Papez’s initial concept of a loop beginning and ending in the hippocampal formation needs to be seen as a much more complex system of hippocampal–diencephalic–cingulate connections. The functions of these multiple interactions might be better viewed as principally providing efferent information from the posterior medial temporal lobe. Both a subcortical diencephalic route (via the fornix) and a cortical cingulate route (via retrosplenial cortex) can be distinguished. These routes provide indirect pathways for hippocampal interactions with prefrontal cortex, with the preponderance of both sets of connections arising from the more posterior hippocampal regions. These multi-stage connections complement the direct hippocampal projections to prefrontal cortex, which principally arise from the anterior hippocampus, thereby creating longitudinal functional differences along the anterior–posterior plane of the hippocampus

Brief approaches to assessing task absorption and enhanced subjective experience: Examining 'short' and 'core' flow in diverse performance domains

The overarching aim of the present study is to expand current approaches to assessing task absorption and subjective experience by assessing two brief measures of flow: (1) ‘short’ flow, reflecting an aggregate or global measure drawn from the ‘long’ multi-item multi-factor flow instrument and (2) ‘core’ flow reflecting the phenomenology of the subjective flow experience itself. We propose that short and core flow have complementary but non-overlapping merits, purposes, and applications. Study 1 examines ‘short’ flow in work (N = 637), sport (N = 239), and music (N = 224). Study 2 examines ‘core’ flow in general school (N = 2,229), extracurricular activity (N = 2,229), mathematics (N = 378), and sport (N = 220) contexts. With few exceptions, both flow measures demonstrated: (a) acceptable model fit, reliability, and distributions, (b) associations with motivation in hypothesized ways, and (c) invariance in factor loadings across diverse samples. Where common data are available, both short and core flow are positively correlated, but with approximately half the variance unexplained they are clearly not the same construct, and so we offer guidance regarding which measure/s to use under particular circumstances. We conclude that the brief flow measures are appropriate for research examining task absorption, subjective experience, and cognate constructs such as motivation

Sozialpsychologische Mechanismen im AfD-Wahlprogramm erkennen: Ein Workshop gegen den Rechts-Populismus

Seit ihrer Gründung zieht die Partei Alternative für Deutschland eine immer größere Wählerschaft an. Sie stellt sich selbst als Protestpartei dar, die für die wahren Bedürfnisse der Bürger*innen eintrete und diese gegen das Establishment und Minderheiten verteidige. Doch was steht hinter den rechtspopulistischen Inhalten, die die Partei vermittelt? Welche Strategien verwendet die AfD um Bürger*innen anzuziehen? Und wie kann man sich diesen erwehren und auch andere zum reflektierten Umgang mit den Parteiinhalten bewegen? Um diese Fragen zu beantworten, wird in diesem Kapitel nach einer kurzen Einleitung zum Thema Populismus ein Workshop vorgestellt, der Menschen für die sozialpsychologischen Mechanismen, die im Wahlprogramm der Alternative für Deutschland wirken, sensibilisieren soll