Objects in space: The neural basis of landmark-based navigation and individual differences in navigational ability

Contains fulltext : 119417.pdf (publisher's version ) (Open Access)Radboud Universiteit Nijmegen, 27 november 2013Promotores : Verhoeven, L.T.W., Hagoort, P. Co-promotor : Janzen, G.179 p

Neurocognitive development of memory for landmarks

Contains fulltext : 139949.pdf (publisher's version ) (Open Access)The capacity to detect landmarks in the environment and to associate each landmark with its spatial context is a fundamental operation for navigation, especially when the context is relevant for successful navigation. Recent evidence suggests robust age-related improvements in contextual memory. The current study investigated the effect of spatial context on landmark recognition memory in children and adolescents. Participants, ages 8-18, watched a video depicting a route through a virtual environment. The location at which landmarks occurred was manipulated to test the hypothesis that memory processes vary as a function of context. Functional magnetic resonance imaging data was acquired while participants performed an old-new recognition memory test of the landmarks. Old compared to new landmarks recruited a network of regions including the hippocampus and the inferior/middle frontal gyrus in all participants. Developmental differences were observed in the functional organization of the parahippocampal gyrus and the anterior cingulate cortex, such that memory representations strengthened linearly with age only when the associated spatial context was relevant for navigation. These results support the view that medial temporal lobe regions become increasingly specialized with development; these changes may be responsible for the development of successful navigation strategies.9 p

Encoding and retrieval of landmark-related spatial cues during navigation: An fMRI study

Contains fulltext : 129251.pdf (publisher's version ) (Closed access)To successfully navigate, humans can use different cues from their surroundings. Learning locations in an environment can be supported by parallel subsystems in the hippocampus and the striatum. We used fMRI to look at differences in the use of object-related spatial cues while 47 participants actively navigated in an open-field virtual environment. In each trial, participants navigated toward a target object. During encoding, three positional cues (columns) with directional cues (shadows) were available. During retrieval, the removed target had to be replaced while either two objects without shadows (objects trial) or one object with a shadow (shadow trial) were available. Participants were informed in blocks about which type of retrieval trial was most likely to occur, thereby modulating expectations of having to rely on a single landmark or on a configuration of landmarks. How the spatial learning systems in the hippocampus and caudate nucleus were involved in these landmark-based encoding and retrieval processes were investigated. Landmark configurations can create a geometry similar to boundaries in an environment. It was found that the hippocampus was involved in encoding when relying on configurations of landmarks, whereas the caudate nucleus was involved in encoding when relying on single landmarks. This might suggest that the observed hippocampal activation for configurations of objects is linked to a spatial representation observed with environmental boundaries. Retrieval based on configurations of landmarks activated regions associated with the spatial updation of object locations for reorientation. When only a single landmark was available during retrieval, regions associated with updating the location of oneself were activated. There was also evidence that good between-participant performance was predicted by right hippocampal activation. This study therefore sheds light on how the brain deals with changing demands on spatial processing related purely to landmarks.16 p

The brain-derived neurotrophic factor Val66Met polymorphism affects encoding of object locations during active navigation

Contains fulltext : 173908.pdf (publisher's version ) (Open Access)The brain-derived neurotrophic factor (BDNF) was shown to be involved in spatial memory and spatial strategy preference. A naturally occurring single nucleotide polymorphism of the BDNF gene (Val66Met) affects activity-dependent secretion of BDNF. The current event-related fMRI study on preselected groups of 'Met' carriers and homozygotes of the 'Val' allele investigated the role of this polymorphism on encoding and retrieval in a virtual navigation task in thirty-seven healthy volunteers. In each trial, participants navigated towards a target object. During encoding, three positional cues (columns) with directional cues (shadows) were available. During retrieval, the invisible target had to be replaced while either two objects without shadows (objects trial) or one object with a shadow (shadow trial) were available. The experiment consisted of blocks, informing participants of which trial type would be most likely to occur during retrieval. We observed no differences between genetic groups in task performance or time to complete the navigation tasks. The imaging results show that Met carriers compared to Val homozygotes activate the left hippocampus more during successful object location memory encoding. The observed effects were independent of non-significant performance differences or volumetric differences in the hippocampus. These results indicate that variations of the BDNF gene affect memory encoding during spatial navigation, suggesting that lower levels of BDNF in the hippocampus results in less efficient spatial memory processing.11 p

Lärande i processoperatörsarbete : möjligheter och utmaningar

Det är drygt femton år sedan Styrelsen för teknisk utveckling (STU), senare NUTEK, initierade det tioåriga forsknings- och  utvecklingsprogrammet Driftsutvecklingssystem för Processindustrin (DUP). Programmet som pågick mellan 1987–1996 omfattade 100 projekt vilka fokuserade processoperatörens arbete, och hur dennes yrkesskicklighet togs tillvara och utvecklades inom processindustrin. Särskilt betonades operatörens förmåga att styra processer och dennes roll i utveckling av effektiva processtöd för att uppnå goda produktionsresultat. DUPprogrammets inriktning mot operatörens lärande och yrkesskicklighet parallellt med utformning av teknik engagerade en rad olika forskare från ett flertal discipliner. DUP-programmet ses som en av de första satsningarna där beteendevetare gavs möjlighet att forska under samma villkor som tekniker för att lösa disciplinöverskridande problem i processindustrin (Tengblad och Walldius, 2007). Per-Erik Ellström var en av forskarna i DUP-programmet som studerade yrkeskompetens och lärande i processoperatörers arbete. I denna text är min ambition att återvända till forskning om processoperatörers arbete och lärande, och särskilt diskutera möjligheter för lärande i högautomatiserad processindustri. Jag gör dock inte anspråk på att ge en heltäckande bild utan fokuserar på några frågor. De frågor jag ställer mig drygt femton år senare är: Har den relativt stabila bild av operatörsarbete som tidigare framträtt i forskningen förändrats? Vilka möjligheter för lärande finns i processoperatörsarbetet? Vilka lärutmaningar finns i processoperatörsarbetet om man blickar framåt

Cognitieve balans: Wat is het en hoe kan het onderwijs erop inspelen?

Item does not contain fulltextCognitieve balans is de competentie te switchen tussen het focussen en het verdelen van aandacht. In hoeverre iemand hierover controle heeft is deels aangeboren. Maar dat betekent niet dat cognitieve balans een statisch gegeven is. De omgeving kan iemand prikkelen zich meer te focussen of juist niet. En we kunnen onszelf leren om meer controle te krijgen over onze cognitieve balans. Leraren en intelligente tutorsystemen kunnen dit leerproces ondersteunen.8 p

Task- and experience-dependent cortical selectivity to features informative for categorization

In this study, we bridge the gap between monkey electrophysiological recordings that showed selective responses to informative features and human fMRI data that demonstrated increased and selective responses to trained objects. Human participants trained with computer-generated fish stimuli. For each participant, two features of the fish were informative for category membership and two features were uninformative. After training, participants showed higher perceptual sensitivity to the informative dimensions. An fMRI adaptation paradigm revealed that during categorization the right inferior frontal gyrus and occipitotemporal cortex were selectively responsive to the informative features. These selective cortical responses were experience dependent; they were not present for the entire trained object, but specific for those features that were informative for categorization. Responses in the inferior frontal gyrus showed category selectivity. Moreover, selectivity to the informative features correlated with performance on the categorization task during scanning. This all suggests that the frontal cortex is involved in actively categorizing objects and that it uses informative features to do so while ignoring those features that do not contribute category information. Occipitotemporal cortex also showed selectivity to the informative features during the categorization task. Interestingly, this area showed a positive correlation of performance during training and selectivity to the informative features and a negative correlation with selectivity to the uninformative features. This indicates that training enhanced sensitivity to trained items and decreased sensitivity to uninformative features. The absence of sensitivity for informative features during a color change detection task indicates that there is a strong component of task-related processing of these features

Development of landmark use for navigation in children: Effects of age, sex, working memory and landmark type

The use of landmarks for navigation develops throughout childhood. Here, we examined the developmental trajectory of egocentric and allocentric navigation based on landmark information in an on-screen virtual environment in 39 5-6-year-olds, 43 7-8-year-olds, and 41 9-10-year-olds. We assessed both categorical performance, indicating the notion of location changes based on the landmarks, as well as metrical performance relating to the precision of the representation of the environment. We investigated whether age, sex, spatial working memory, verbal working memory, and verbal production of left and right contributed to the development of navigation skills. In egocentric navigation, Categorical performance was already above chance at 5 years of age and was positively related to visuo-spatial working memory and the production of left/right, whereas metrical performance was only related to age. Allocentric navigation started to develop between 5 and 8 years of age and was related to sex, with boys outperforming girls. Both boys and girls seemed to rely more on directional landmark information as compared to positional landmark information. To our knowledge, this study is the first to give insight into the relative contribution of different cognitive abilities to navigation skills in school-aged children

Comparison of explicit vs. implicit measurements in predicting food purchases

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The dynamics of memory consolidation of landmarks

Contains fulltext : 168730.pdf (publisher's version ) (Closed access)Navigating through space is fundamental to human nature and requires the ability to retrieve relevant information from the remote past. With the passage of time, some memories become generic, capturing only a sense of familiarity. Yet, others maintain precision, even when acquired decades ago. Understanding the dynamics of memory consolidation is a major challenge to neuroscientists. Using functional magnetic resonance imaging, we systematically examined the effects of time and spatial context on the neural representation of landmark recognition memory. An equal number of male and female subjects (males N=10, total N=20) watched a route through a large-scale virtual environment. Landmarks occurred at navigationally relevant and irrelevant locations along the route. Recognition memory for landmarks was tested directly following encoding, 24 hours later and 30 days later. Surprisingly, changes over time in the neural representation of navigationally relevant landmarks differed between males and females. In males, relevant landmarks selectively engaged the parahippocampal gyrus (PHG) regardless of the age of the memory. In females, the response to relevant landmarks gradually diminished with time in the PHG but strengthened progressively in the inferior frontal gyrus (IFG). Based on what is known about the functioning of the PHG and IFG, the findings of the current study suggest that males maintain access to the initially formed spatial representation of landmarks whereas females become strongly dependent on a verbal representation of landmarks with time. Our findings yield a clear objective for future studies.12 p