14 research outputs found
Route repetition and route retracing: effects of cognitive aging
No full textRetracing a recently traveled route is a frequent navigation task when learning novel routes or exploring unfamiliar environments. In the present study we utilized virtual environments technology to investigate age-related differences in repeating and retracing a learned route. In the training phase of the experiment participants were guided along a route consisting of multiple intersections each featuring one unique landmark. In the subsequent test phase, they were guided along short sections of the route and asked to indicate overall travel direction (repetition or retracing), the direction required to continue along the route, and the next landmark they would encounter. Results demonstrate age-related deficits in all three tasks. More specifically, in contrast to younger participants, the older participants had greater problems during route retracing than during route repetition. While route repetition can be solved with egocentric response or route strategies, successfully retracing a route requires allocentric processing. The age-related deficits in route retracing are discussed in the context of impaired allocentric processing and shift from allocentric to egocentric navigation strategies as a consequence of age-related hippocampal degeneration. - See more at: http://journal.frontiersin.org/Journal/10.3389/fnagi.2012.00007/abstract#sthash.xK4Htsfy.dpu
Metaphor explanation attenuates the right-hand preference for depictive co-speech gestures that imitate actions.
No full textDifferential activation levels of the two hemispheres due to hemispheric specialization for various linguistic processes might determine hand choice for co-speech gestures. To test this hypothesis, we compared hand choices for gesturing in 20 healthy right-handed participants during explanation of metaphorical vs. non-metaphorical meanings, on the assumption that metaphor explanation enhances the right hemisphere contribution to speech production. Hand choices were analyzed separately for: depictive gestures that imitate action (“character viewpoint gestures,” [McNeill, D. (1992). Hand and mind. What gestures reveal about thought. Chicago: University of Chicago Press.]), depictive gestures that express motion, relative locations, and shape (“observer viewpoint gestures”), and “abstract deictic gestures.” It was found that the right-hand over left-hand preference was significantly weaker in the metaphor condition than in the non-metaphor conditions for depictive gestures that imitated action. Findings suggest that the activation of the right hemisphere in the metaphor condition reduces the likelihood of left hemisphere generation of gestures that imitate action, thus attenuating the right-hand preference
Human place and response learning: navigation strategy selection, pupil size and gaze behavior.
No full textIn this study, we examined the cognitive processes and ocular behavior associated with on-going navigation strategy choice using a route learning paradigm that distinguishes between three different wayfinding strategies: an allocentric place strategy, and the egocentric associative cue and beacon response strategies. Participants approached intersections of a known route from a variety of directions, and were asked to indicate the direction in which the original route continued. Their responses in a subset of these test trials allowed the assessment of strategy choice over the course of six experimental blocks. The behavioral data revealed an initial maladaptive bias for a beacon response strategy, with shifts in favor of the optimal configuration place strategy occurring over the course of the experiment. Response time analysis suggests that the configuration strategy relied on spatial transformations applied to a viewpoint-dependent spatial representation, rather than direct access to an allocentric representation. Furthermore, pupillary measures reflected the employment of place and response strategies throughout the experiment, with increasing use of the more cognitively demanding configuration strategy associated with increases in pupil dilation. During test trials in which known intersections were approached from different directions, visual attention was directed to the landmark encoded during learning as well as the intended movement direction. Interestingly, the encoded landmark did not differ between the three navigation strategies, which is discussed in the context of initial strategy choice and the parallel acquisition of place and response knowledge
Spatial navigation from same and different directions: The role of executive functions, memory and attention in adults with Autism Spectrum Disorder
No full textTo resolve some of the inconsistencies in existing research into spatial navigation in Autism Spectrum Disorder (ASD), we tested two large age- and ability-matched groups of ASD and typically developing (TD) participants for their spatial navigation abilities in a route learning task, which has been shown to shed light on the strategies participants employ when navigating complex environments. Participants studied a route through a virtual maze by watching a short video of a first-person perspective navigating a maze. The maze included four four-way intersections that were each marked with two unique landmarks in two corners of the intersection. At test, static images of the intersections, either as seen during the video or as approached from a different direction, were presented and participants had to indicate in which direction they would need to travel (straight, left or right) in order to follow the originally studied route. On both types of test trials, the ASD group performed worse and their difficulties were related to reduced cognitive flexibility. Eye-movement data and followup item-memory tests suggested that navigation difficulties may have been related to differences in attention during encoding and less spontaneous use of landmarks as cues for navigation. Spatial navigation performance was best predicted by memory for landmarks as well as by executive functions. The results are discussed in relation to theories of underlying navigation-related brain regions. More research is needed to disentangle the influence of executive functions, memory and attention on spatial navigation
Maladaptive bias for extrahippocampal navigation strategies in aging humans.
No full textEfficient 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
Ageing specifically impairs switching to an allocentric navigational strategy
No full textNavigation abilities decline with age, partly due to deficits in numerous component processes. Impaired switching between these various processes (i.e. switching navigational strategies) is also likely to contribute to age-related navigational impairments. We tested young and old participants on a virtual plus maze task, expecting older participants to exhibit a specific strategy switching deficit, despite unimpaired learning of allocentric (place) and egocentric (response) strategies following reversals within each strategy. Our initial results suggested that older participants performed worse during place trial blocks but not response trial blocks, as well as in trial blocks following a strategy switch but not those following a reversal. However, we then separated trial blocks by both strategy and change type, revealing that these initial results were due to a more specific deficit in switching to the place strategy. Place reversals and switches to response, as well as response reversals, were unaffected. We argue that this specific ‘switch-to-place' deficit could account for apparent impairments in both navigational strategy switching and allocentric processing, and contributes more generally to age-related decline in navigation
Differences in navigation performance and postpartal striatal volume associated with pregnancy in humans.
No full textPregnancy is accompanied by prolonged exposure to high estrogen levels. Animal studies have shown that estrogen influences navigation strategies and, hence, affects navigation performance. High estrogen levels are related to increased use of hippocampal-based allocentric strategies and decreased use of striatal-based egocentric strategies. In humans, associations between hormonal shifts and navigation strategies are less well studied. This study compared 30 peripartal women (mean age 28 years) to an age-matched control group on allocentric versus egocentric navigation performance (measured in the last month of pregnancy) and gray matter volume (measured within two months after delivery). None of the women had a previous pregnancy before study participation. Relative to controls, pregnant women performed less well in the egocentric condition of the navigation task, but not the allocentric condition. A whole-brain group comparison revealed smaller left striatal volume (putamen) in the peripartal women. Across the two groups, left striatal volume was associated with superior egocentric over allocentric performance. Limited by the cross-sectional study design, the findings are a first indication that human pregnancy might be accompanied by structural brain changes in navigation-related neural systems and concomitant changes in navigation strategy
Individual differences in frequency and saliency of speech-accompanying gestures : the role of cognitive abilities and empathy
No full textThe present study concerns individual differences in gesture production. We used correlational and multiple regression analyses to examine the relationship between individuals’ cognitive abilities and empathy levels and their gesture frequency and saliency. We chose predictor variables according to experimental evidence of the functions of gesture in speech production and communication. We examined 3 types of gestures: representational gestures, conduit gestures, and palm-revealing gestures. Higher frequency of representational gestures was related to poorer visual and spatial working memory, spatial transformation ability, and conceptualization ability; higher frequency of conduit gestures was related to poorer visual working memory, conceptualization ability, and higher levels of empathy; and higher frequency of palm-revealing gestures was related to higher levels of empathy. The saliency of all gestures was positively related to level of empathy. These results demonstrate that cognitive abilities and empathy levels are related to individual differences in gesture frequency and saliency
Navigational strategy switching in ageing
No full textWith advancing age, many cognitive faculties deteriorate, and navigation abilities
may be among those most affected. The majority of previous work investigating
navigation impairments in ageing has focused on allocentric processing, attributing
deficits to hippocampal dysfunction. However, real-world navigation is dependent
upon numerous different strategies, as well as the ability to flexibly switch between
them. Outside the context of navigation, it has been demonstrated that strategy
switching, thought to be coordinated by regions of prefrontal cortex and the locus
coeruleus-noradrenergic system, is also susceptible to the effects of ageing. Deficits
in navigational strategy switching, and prefrontal or noradrenergic dysfunction, are
therefore also likely to contribute to age-related navigation impairments. The work
presented in this thesis aimed to explore age-related impairments in strategy
switching within the context of navigation, and the underlying neural mechanisms in
terms of a prefrontal-noradrenergic model of switching.
The studies presented in Chapter Three assessed the use of allocentric and egocentric
navigational strategies by young and older people. Older participants tended to use
an egocentric strategy where an allocentric strategy was required, possibly due to a
difficulty in switching to the appropriate allocentric strategy. In Chapter Four, I
provide an account of two studies directly assessing navigational strategy switching,
using two different tasks based in virtual reality. The first study utilised a virtual
adaptation of the plus maze task, involving switching between an allocentric place
strategy and an egocentric response strategy, and demonstrated that older participants
were specifically impaired at switching to the place strategy. The second study used a
more realistic task set in a virtual town environment, which involved switching from
an egocentric route-following strategy to an allocentric wayfinding strategy, and also
demonstrated an age-related deficit in switching to an allocentric strategy.
In Chapter Five, I begin to explore the mechanisms underlying impaired navigational
strategy switching in ageing. Firstly, I describe a further behavioural study that used
variants of the virtual plus maze and a navigational gambling task to demonstrate a contribution of impaired decision making to the deficit in switching to an allocentric
strategy. This indicates that the deficit can be attributed, at least in part, to prefrontal
dysfunction. A second study presented in the same chapter demonstrated that
practising orienteering does not protect against decline in navigational strategy
switching ability with ageing. Chapter Six provides an account of my direct
assessment of the neural bases of navigational strategy switching using functional
magnetic resonance imaging. In young subjects, I found some evidence in support of
the roles of prefrontal regions in navigational strategy switching. However, I was
unable to complete development of a task suitable for assessing age differences in
functional activation of brain regions involved in navigational strategy switching.
The final experimental study, included in Chapter Seven, assessed pupil size and
heart rate as physiological correlates of noradrenergic activity during performance of
the virtual plus maze. Both young and old participants demonstrated a noradrenergic
response to all strategy changes, suggesting that impairments are more likely
attributable to dysfunction of prefrontal cortex than of the locus coeruleus, although
some subtle effects suggested that noradrenergic dysfunction does have some effect
on navigational strategy switching deficits. In the same chapter, I report the results of
a meta-analysis of data from five of the preceding studies, suggesting that deficits in
both strategy switching and allocentric processing combine to produce a greater
impairment in switching to an allocentric strategy.
The main finding of this series of studies is that navigational strategy switching is
impaired in ageing, which may contribute to the more widely reported difficulties
that older people have with navigation. My work also provides evidence in support
of a prefrontal-noradrenergic model of navigational strategy switching, and suggests
that dysfunction of prefrontal cortex and, to a lesser extent, the locus coeruleus-noradrenergic system is responsible for decline in navigational strategy switching
ability with ageing. In conclusion, this thesis draws attention to the important role of
deficient executive processing and dysfunction of extra-hippocampal brain regions in
age-related navigation impairments
