Maladaptive bias for extrahippocampal navigation strategies in aging humans.

Efficient spatial navigation requires not only accurate spatial knowledge but also the selection of appropriate strategies. Using a novel paradigm that allowed us to distinguish between beacon, associative cue, and place strategies, we investigated the effects of cognitive aging on the selection and adoption of navigation strategies in humans. Participants were required to rejoin a previously learned route encountered from an unfamiliar direction. Successful performance required the use of an allocentric place strategy, which was increasingly observed in young participants over six experimental sessions. In contrast, older participants, who were able to recall the route when approaching intersections from the same direction as during encoding, failed to use the correct place strategy when approaching intersections from novel directions. Instead, they continuously used a beacon strategy and showed no evidence of changing their behavior across the six sessions. Given that this bias was already apparent in the first experimental session, the inability to adopt the correct place strategy is not related to an inability to switch from a firmly established response strategy to an allocentric place strategy. Rather, and in line with previous research, age-related deficits in allocentric processing result in shifts in preferred navigation strategies and an overall bias for response strategies. The specific preference for a beacon strategy is discussed in the context of a possible dissociation between beacon-based and associative-cue-based response learning in the striatum, with the latter being more sensitive to age-related changes

Methodiek Schoolverlatersinformatiesysteem 1998

Dit werkdocument gaat in op de methodiek die in het uitvoeringsjaar 1998 is gehanteerd binnen het schoolverlatersonderzoek zoals dat door het ROA wordt uitgevoerd. Dit betreft de enquêtes Registratie van Uitstroom en Bestemming van Schoolverlaters (RUBS), HBO-Monitor en WO-Monitor. Sinds 1996 is het ROA-schoolverlatersonderzoek in vergaande mate geïntegreerd. Hierdoor is een vergelijkbaar systeem ontstaan, het Schoolverlatersinformatiesysteem (SIS) genoemd, met gegevens over schoolverlaters uit vrijwel het gehele secundair en tertiair onderwijs. In het kader van het onderzoek binnen dit informatiesysteem zijn onder andere het rapport Schoolverlaters tussen onderwijs en arbeidsmarkt 1998 en een bijbehorende bijlage Statistische Bijlage gepubliceerd. Daarnaast is er een specifieke rapportage verschenen over de arbeidsmarktpositie van de afgestudeerden van het HBO. De lerarenopleidingen zullen in een aparte rapportage worden behandeld. Voor de afgestudeerden van het kunstvakonderwijs verschijnt in de loop van 2000 ook een specifiek rapport. Tevens zullen de belangrijkste resultaten van de WO-Monitor in een landelijke rapportage worden gepresenteerd. Naast de hierboven genoemde schoolverlatersonderzoeken zijn in 1998 enkele, in 1997 gestarte, ''pilot''-onderzoeken voortgezet. Dit betreft enquêtes onder schoolverlaters van de Beroepsbegeleidende leerweg (BBL) en ex-cursisten van het Voortgezet Algemeen Volwassenen Onderwijs (VAVO). Er is eveneens een éénmalige enquête verricht onder ex-cursisten van de basiseducatie (BE). Hierover zal in aparte rapportages zowel methodologisch als inhoudelijk verslag worden gedaan.labour market entry and occupational careers;

Systematic underreproduction of time is independent of judgment certainty

We recently proposed that systematic underreproduction of time is caused by a general judgment bias towards earlier responses, instead of reflecting a genuine misperception of temporal intervals. Here we tested whether this bias can be explained by the uncertainty associated with temporal judgments. We applied transcranial magnetic stimulation (TMS) to inhibit neuronal processes in the right posterior parietal cortex (PPC) and tested its effects on time discrimination and reproduction tasks. The results show increased certainty for discriminative time judgments after PPC inhibition. They suggest that the right PPC plays an inhibitory role for time perception, possibly by mediating the multisensory integration between temporal stimuli and other quantities. Importantly, this increased judgment certainty had no influence on the degree of temporal underreproduction. We conclude that the systematic underreproduction of time is not caused by uncertainty for temporal judgments

Destination choices of international students in the Netherlands:A meso‐level analysis of higher education institutions and cities

This study quantitatively investigates enrolments of international students using data that contains nearly every student in the Netherlands for the years 2016–2019. Using this data, we are able to perform a meso-level analysis where we could investigate the characteristics of higher education institutions (HEIs) and cities in international student mobility. This research contributes to the literature by studying variation between HEIs and by focusing on actual enrolments instead of relying on survey results. Such meso-level studies have thus far been very rare, especially on this scale. Although there are commonalities between types of degrees, we find mixed results for academic and city characteristics, and it appears that academic factors are more important for master students while for bachelor students city characteristics have stronger effects. The effect of having already existing stocks of international students appears to be important for all types of degrees. Aside from differences between bachelor and master students, our findings also suggest that HEIs might directly influence international student flows as this would explain some of our results. Although this study only focuses on the Netherlands, it opens up many avenues for future comparative research on the destination choices of international students and the role of HEIs

High incidence of severe ischaemic complications in patients with giant cell arteritis irrespective of platelet count and size, and platelet inhibition

Objective. Vision loss and ischaemic stroke are feared complications in GCA. We investigated how platelet count and size and platelet inhibition with ASA relate to ischaemic complications in patients with GCA. Methods. Charts of patients with GCA were retrospectively analysed. Jaw claudication, amaurosis fugax, blurred vision, ischaemic stroke and permanent visual loss were classified as ‘ischaemic events'; ischaemic stroke and permanent visual loss were sub-grouped as ‘severe ischaemic events'. The incidence of ischaemia and the association to the pre-defined covariates age, fever, ESR, platelet count and size and ASA treatment were assessed. Results. Eighty-five patients (mean age 73 yrs, 60% women, 78% biopsy-proven) were included in the analysis. Of the 85 patients, 62 (73%) presented with ischaemic events, 29/85 patients (34%) with severe ischaemic events. At the time of diagnosis 22/85 patients (26%) were treated with ASA. Of these 22 patients, 15 (68%) presented with ischaemic events, 7/22 patients (32%) with severe ischaemic events. In multivariate analysis, neither platelet count nor size or ASA treatment were significantly associated with ischaemic or severe ischaemic events. Conclusions. The incidence of severe ischaemic events in patients with GCA was high, irrespective of platelet count and size and established ASA treatmen

The Aging Navigational System

The discovery of neuronal systems dedicated to computing spatial information, composed of functionally distinct cell types such as place and grid cells, combined with an extensive body of human-based behavioral and neuroimaging research has provided us with a detailed understanding of the brain's navigation circuit. In this review, we discuss emerging evidence from rodents, non-human primates, and humans that demonstrates how cognitive aging affects the navigational computations supported by these systems. Critically, we show 1) that navigational deficits cannot solely be explained by general deficits in learning and memory, 2) that there is no uniform decline across different navigational computations, and 3) that navigational deficits might be sensitive markers for impending pathological decline. Following an introduction to the mechanisms underlying spatial navigation and how they relate to general processes of learning and memory, the review discusses how aging affects the perception and integration of spatial information, the creation and storage of memory traces for spatial information, and the use of spatial information during navigational behavior. The closing section highlights the clinical potential of behavioral and neural markers of spatial navigation, with a particular emphasis on neurodegenerative disorders

Testing of High Voltage Surge Protection Devices for Use in Liquid Argon TPC Detectors

In this paper we demonstrate the capability of high voltage varistors and gas discharge tube arrestors for use as surge protection devices in liquid argon time projection chamber detectors. The insulating and clamping behavior of each type of device is characterized in air (room temperature), and liquid argon (90~K), and their robustness under high voltage and high energy surges in cryogenic conditions is verified. The protection of vulnerable components in liquid argon during a 150 kV high voltage discharge is also demonstrated. Each device is tested for argon contamination and light emission effects, and both are constrained to levels where no significant impact upon liquid argon time projection chamber functionality is expected. Both devices investigated are shown to be suitable for HV surge protection applications in cryogenic detectors.Comment: 22 pages, 18 figures v2: reduced file size for journal submissio

The organizational principles of de-differentiated topographic maps in somatosensory cortex

Topographic maps are a fundamental feature of cortex architecture in the mammalian brain. One common theory is that the de-differentiation of topographic maps links to impairments in everyday behavior due to less precise functional map readouts. Here, we tested this theory by characterizing de-differentiated topographic maps in primary somatosensory cortex (SI) of younger and older adults by means of ultra-high resolution functional magnetic resonance imaging together with perceptual finger individuation and hand motor performance. Older adults' SI maps showed similar amplitude and size to younger adults' maps, but presented with less representational similarity between distant fingers. Larger population receptive field sizes in older adults' maps did not correlate with behavior, whereas reduced cortical distances between D2 and D3 related to worse finger individuation but better motor performance. Our data uncover the drawbacks of a simple de-differentiation model of topographic map function, and motivate the introduction of feature-based models of cortical reorganization