PRISM :: Browsing by Author "Iaria, Giuseppe"

Browsing by Author "Iaria, Giuseppe"

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Open Access
Age and gender differences in various topographical orientation strategies
(2011) Liu, Irene; Iaria, Giuseppe
Open Access
Assessing Spatial Orientation Skills in Athletes After Sustaining a Concussion: A Pilot Study
(2019-07-03) McFarlane, Liam Heath; Iaria, Giuseppe; Yeates, Keith Owen; Schneider, Kathryn J.; Brooks, Brian L.
As a pilot study I investigated whether suffering a sport-related concussion (SRC) affected adolescent hockey participants’ abilities to form and use cognitive maps. To assess cognitive map formation and use a modified version of the Spatial Configuration Task (m-SCT), a computerized tool that has been shown to quantitatively measure an individual’s ability to form and use cognitive maps (Burles, 2014), was administered to a group of 18 adolescent hockey participants suffering from a SRC and a group of 19 adolescent controls with similar age, sex, handedness and no reported history of concussion. Using age as a covariate, an ANCOVA revealed a significant difference between athletes’ with a concussion (M = 42.61, SD = 7.22) m-SCT performances when compared to healthy controls’ (M = 48.32, SD = 8.27; F(1,34) = 5.82, p = .021, d ̂ = -0.72). As a group, adolescent participants with concussion performed significantly worse than the control group. There was no significant difference between groups average response time and no significant correlation between m-SCT performance and athlete reported symptoms on the Sport Concussion Assessment Tool, version 5 (SCAT5). However, a post hoc one-tailed Pearson’s partial correlations analysis revealed that participants with a concussion, as an independent group, show a positive relationship between average response time and performance on the m-SCT (r(15) = .51, p = .038). A discussion is provided and focuses on implications of the observed groups difference in performances on the m-SCT, the study’s limitations and recommendations for future studies wishing to investigate cognitive map formation in adolescents’ athletes with concussion. Additionally, this study also provides preliminary results showing that the Spatial Configuration Task may be modified in difficulty when assessing cognitive map formation in adolescents and children.
Open Access
Assessing Topographical Orientation Skills in Cannabis Users
(2012-01-03) Palermo, Liana; Bianchini, Filippo; Iaria, Giuseppe; Tanzilli, Antonio; Guariglia, Cecilia
The long-term effects of cannabis on human cognition are still unclear, but, considering that cannabis is a widely used substance and, overall, its potential use in therapeutic interventions, it is important to evaluate them. We hypothesize that the discrepancies among studies could be attributed to the specific cognitive function investigated and that skills subserved by the hippocampus, such as the spatial orientation abilities and, specifically, the ability to form and use cognitive maps, should be more compromised than others. Indeed it has been showed that cannabis users have a reduced hippocampus and that the hippocampus is the brain region in which cannabis has the greatest effect since it contains the highest concentration of cannabinoid receptors. To test this hypothesis we asked 15 heavy cannabis users and 19 nonusers to perform a virtual navigational test, the CMT, that assesses the ability to form and use cognitive maps. We found that using cannabis has no effect on these hippocampus-dependent orientation skills. We discuss the implications of our findings and how they relate to evidence reported in the literature that the intervention of functional reorganization mechanisms in cannabis user allows them to cope with the cognitive demands of navigational tasks.
Open Access
Brain Function in Early Childhood: Individual Differences in Age and Attentive Traits
(2023-09-22) Tansey, Ryann Claire; Bray, Signe Lauren; Dewey, Deborah Maryanne; Iaria, Giuseppe; Kopala Sibley, Daniel Cameron; Cusack, Rhodri
Children, like adults, are unique individuals with complex interwoven relationships between brain function, behaviour, and phenotypic traits, which further interact with rapid developmental processes. A nuanced description of variability between children will add to our knowledge of how they think and behave, and potentially advance the development of personalized early interventions. With functional magnetic resonance imaging (fMRI), we have gained insight into brain responses – however, due to practical considerations, we have been unable to render a complete understanding of brain-behaviour relationships in young children. The use of naturalistic stimuli in fMRI studies has increased the ecological validity and the retention of developmental neuroimaging data. In this dissertation, I sought to explore the relationships between age, attentive traits, and inter-individual variability of brain function in young children in naturalistic paradigms. I conducted a scoping review to synthesize the current and historical task- and naturalistic-fMRI literature on the development of visual processing in the brain, through the lens of two influential theories: the interactive specialization and maturational frameworks. I found that while there is generally a consensus of progressive development of visual brain function throughout childhood, there is not enough evidence to fully support other aspects of these theories. I also conducted two experiments, using naturalistic fMRI and an analysis technique called inter-subject correlation (ISC), which quantifies the spatiotemporal similarity of brain activity between individuals, to explore how age and attentive traits affect inter-individual variability of brain function in children aged 4-8 years. I found that children’s brain responses to movies “homogenized” with increasing age in our sample, with greater variability seen in the younger children. Further, both inattention and hyperactivity were associated with ISC in the sample, though the relationships with these traits were different in widespread regions of the brain. Together, my research advances our understanding of functional brain responses in children and underscores the importance of an individual differences approach to developmental neuroimaging.
Open Access
Cognitive and Emotional Empathy in Individuals with Spinal Cord Injury
(2019-02-10) Guadagni, Veronica; Sarà, Marco; Conson, Massimiliano; Carolei, Antonio; Sacco, Simona; Vadini, Silvia; Pistarini, Caterina; Barbonetti, Arcangelo; Iaria, Giuseppe; Pistoia, Francesca
Background. Empathy has been conceptualized as comprising a cognitive and an emotional component, the latter being further divided into direct and indirect aspects, which refer, respectively, to the explicit evaluation of the observer’s feelings while attending someone in an emotional situation and to the physiological response of the observer. Empathy has been previously investigated in several neurological disorders. Objective. This study is aimed at investigating empathy in patients with spinal cord injury (SCI). We hypothesize that, due to deafferentation following their injury, SCI patients will display difficulty in the processing of emotional stimuli and blunted empathic responses as compared to healthy controls. Materials and Methods. 20 patients with spinal cord injury (SCI) (12 males and 8 females, mean , standard deviation years; mean , years) were included in the study and compared to 20 matched healthy subjects. Participants were investigated using the State-Trait Anxiety Inventory (Form Y) (STAI-Y), the Beck Depression Scale, and the Toronto Alexithymia Scale. Moreover, participants were further evaluated by means of the Interpersonal Reactivity Index (IRI), which explores both cognitive and emotional aspects of empathy, and through an experimental protocol based on the use of a modified version of the computerized Multifaceted Empathy Test (MET) to evaluate emotional (direct and indirect) empathy and the ability to judge the valence of complex emotional scenes. Results. As compared to healthy controls, SCI patients reported higher scores on the Perspective-Taking subscale of the IRI, while, on the modified MET, they were less accurate in identifying the valence of neutral scenes, notwithstanding their spared direct and indirect emotional empathy ability. Furthermore, we found a significant negative correlation between the time interval since injury and the direct emotional empathy scores on the positive images, as well as a negative correlation with the indirect emotional empathy scores on both positive and neutral images, indicating a blunting of the empathic responses as time elapses. Conclusion. Results suggest that SCI patients, when analyzing the meaning of emotional stimuli, tend to rely on a cognitive empathy strategy rather than on emotion simulation.
Open Access
Context Effects on Beauty Ratings of Painted Artworks: Contrast, Contrast, Everywhere!
(2016) Tousignant, Cody; Bodner, Glen; Pexman, Penny; Iaria, Giuseppe; Weinhardt, Justin; Zellner, Debra
To explore how context influences the subjective beauty of painted artworks, I presented average-beauty target paintings in the context of either low-beauty or high-beauty context paintings. Experiment 1 also factorially varied whether target and context paintings were of similar or different styles, were presented sequentially or simultaneously, and whether 2 or 10 paintings were rated. Target paintings were consistently deemed more beautiful when presented with low-beauty (vs. high-beauty) context paintings. This contrast effect was not modulated by the other three factors. In Experiments 2a-c, context beauty again yielded contrast effects, even though a variety of methods were used to try to elicit assimilation effects. Experiment 3a-b examined whether the “contrast everywhere” pattern might be due to participants not perceiving target and context paintings as similar. Consistent with that possibility, similarity ratings for context-target pairs were generally low, even though they were higher for similar (vs. different) style targets, and for simultaneous (vs. sequential) presentation. My results provided some support, and some challenges, for a selective accessibility model and a range-frequency model. Critically, both models will need to better specify how similarity is assessed. To better elucidate how context influences stimulus evaluation, I discuss the need to collect independent measures of similarity perception in future research.
Open Access
Detecting neuroplastic changes in astronauts
(2023-06) Berger, Lila; Iaria, Giuseppe; Lebel, Catherine; Williams, Rebecca Jayde; Kam, Julia W. Y.
Understanding the impact of space travel on the brain has become increasingly important as the space industry plans to send humans to Mars within the next decade. Magnetic Resonance Imaging (MRI) research has indicated significant and inconsistent structural changes in the brains of astronauts as a result of spaceflight. Volumetric brain changes in astronauts have the potential to cause significant and even life-threatening consequences. Recently, research has demonstrated that reports of these volumetric changes may be corrupted by the upward shift of the brain within the skull and a redistribution of cerebrospinal fluid (CSF) resulting from microgravity. This CSF shift may create errors in the classification of the dura mater from other various tissue types, producing erroneous claims of volumetric neuroplastic brain changes resulting from spaceflight. This research was developed with the aim of reducing these classification errors through the investigation of a variety of newer MRI scans and protocols that may better account for a physical displacement of the brain and CSF in the skull. Manual tissue segmentation was performed on the standard modality to provide a comparison measure. Automated tissue segmentation was performed in each modality. Dice coefficients were calculated, and a repeated measures factorial analysis of variance was performed, followed by paired-samples t-tests. Total grey matter volume measures were obtained, and a repeated-factorial analysis of variance as well as follow up comparisons were performed for this measure as well. The primary hypothesis for this work was not confirmed, as no certain modality consistently outperformed MPRAGE across all automated software. This research may help inform modality selection for astronauts, as well as caution reporting or interpreting neuroplastic brain changes in astronauts using standard methodology.
Open Access
Development of topographical orientation skills in seven to ten year old children
(2017) Liu, Irene; Iaria, Giuseppe; Graham, Susan; MacMaster, Frank; Drefs, Michelle; Uttal, David; Iaria, Giuseppe
In this dissertation, I investigated children’s development of topographical orientation skills. Specifically, I examined children’s performance on a navigation task in a virtual museum. In Chapter 2, I described the methodology used in this experiment. The computer task comprised of an interactive game that consisted of three sections: a practice motor task, a guided tour around a virtual museum, and a testing phase. After children were introduced to the environment, they were required to navigate from one location of the museum to a goal location as quickly as possible. Game performance was assessed by how much time and travel distance were required to reach a target location. In order to assess different cognitive domains supporting topographical orientation skills, a neuropsychological battery was administered. Finally, both children and parents completed self-rated questionnaires of the children’s general spatial behaviours. In Chapter 3, the main experimental results were described. Game performance was significantly correlated with age and several neuropsychological measures with emphasis on visual spatial processing. Game performance was also correlated with history of gaming experience and technology use. A multiple linear regression analysis revealed that game performance was best explained by performance on spatial working memory and visual-spatial organization tasks, once video game experience was accounted for. Only children’s self-reported ratings of their spatial orientation and navigation skills were correlated with one of two measures of game performance, whereas parents’ ratings were not. When compared to adult performance on the computer game, even the oldest group of children tested was still not as efficient as adults in solving the task, suggesting that development of topographical orientation skills continue well into adolescence and young adulthood. Chapter 4 summarized and explored the aforementioned findings in greater detail. Additional statistical analyses and discussion regarding the pilot study, a group of children who participated in a repeat session of the computer game, and a group of younger children tested are described in Appendix B.
Open Access
Disambiguating the Role of the Retrosplenial Complex in Human Navigation
(2018-06-14) Burles, Clayton Ford; Iaria, Giuseppe; Protzner, Andrea B.; MacMaster, Frank P.
The role of the human retrosplenial cortex in spatial orientation and navigation has been obscured by a long history of ambiguous localization, beginning as early as Brodmann’s original depiction which intentionally overrepresented it’s extent. While some modern atlases of the brain exclude this region, many include a surprisingly generous delineation; this has resulted in a very large area of the medial parietal cortex implicitly viewed as being equipotentially involved in spatial orientation and navigation. In this thesis, I provide novel evidence of a more precise paradigm by which we can understand the role of the ‘retrosplenial cortex’, i.e. the posterior cingulate, in spatial orientation and navigation. First, from fMRI activity evoked in a novel spatial task, but subsequently from a meta-analysis of the literature more generally, we have identified that ventral portions of the posterior cingulate are relatively more engaged in encoding spatial information, whereas dorsal portions are more involved in recalling and computing spatial information or representations. Not simply descriptive, this delineation proved valuable in characterizing the neural correlates of a lifelong developmental condition in which individuals get lost on a daily basis in very familiar surroundings, a condition known as Developmental Topographical Disorientation (DTD). In fact, we identified that the dorsal posterior cingulate displays far greater differences then the ventral posterior cingulate in functional connectivity between individuals with DTD and healthy controls; these findings would not have been uncovered with traditional delineations of the retrosplenial cortex. Other studies will undoubtedly benefit from appreciating these functional subregions when analyzing or interpreting activity within the posterior cingulate evoked by spatial orientation tasks. A clear understanding of the neural correlates of spatial orientation and navigation in humans will benefit greatly from future research validating this posterior cingulate delineation, as well as extending increasingly meticulous attention to the location of activity evoked in the posterior cingulate and other brain regions.
Open Access
Electrophysiological Correlates of Naturally Occurring Thought Patterns
(2024-01-24) Park, YeEun; Kam, Julia; Bray, Signe; Iaria, Giuseppe; Protzner, Andrea
Humans engage in a continuous flow of thoughts throughout the day. These thoughts change depending on the context in which they occur and correspond with unique patterns of connectivity within and between neural networks. Notably, less is known about the electrophysiological signatures of these thought patterns. To address this question, this study examined the interplay between thought patterns and electrophysiological activity in internally and externally oriented contexts. Forty-one participants were asked to attend internally to their own thoughts (thought focus condition) and externally to a set of videos (video focus condition), during which they were asked to report various dimensions of their ongoing thoughts. We implemented principal component analysis on the ratings of these multiple thought dimensions and identified three thought patterns (representing co-occurring thought dimensions): present external thought, goal-oriented future thoughts, and freely moving external positive thoughts. We found that these three thought patterns differentially associated with the experimental conditions and EEG measures. Present external thought was more closely associated with the video focus condition and showed increased frontal alpha and posterior alpha. Goal-oriented future thoughts increased during the thought versus video focus condition but was not significantly linked to any EEG measures. Freely moving external positive thoughts were more strongly associated with the video focus condition and showed decreased frontal alpha activity. Taken together, our results highlight the complex relationship between thought patterns and electrophysiological activity in different contexts.
Open Access
The Emergence of Cognitive Maps for Spatial Navigation in 7- to 10-Year-Old Children
(Society for Research In Child Development, 2019-07-08) Burles, Ford; Liu, Irene; Hart, Chelsie; Murias, Kara; Graham, Susan; Iaria, Giuseppe
Although much is known about adults' ability to orient by means of cognitive maps (mental representations of the environment), it is less clear when this important ability emerges in development. In the present study, 97 seven- to 10-year-olds and 26 adults played a video game designed to investigate the ability to orient using cognitive maps. The game required participants to reach target locations as quickly as possible, necessitating the identification and use of novel shortcuts. Seven- and 8-year-olds were less effective than older children and adults in using shortcuts. These findings provide clear evidence of a distinct developmental change around 9 years of age when children begin to proficiently orient and navigate using cognitive maps.
Open Access
How spatial is spatial language? Investigating the relationship between spatial cognition and abstract language processing
(2020-06-23) Hannah, Jaimy Anne; Iaria, Giuseppe; Pexman, Penny M.; Curtin, Suzanne; Graham, Susan A.
The present study aimed to explore the relationship between spatially grounded language and spatial cognition. According to embodied cognition, sensitivity to spatial grounding should be related to experience with spatial cognition. Participants completed three language tasks assessing their sensitivity to spatial grounding and three spatial tasks assessing different facets of spatial cognition. These language tasks were derived from previous studies that showed spatial grounding effects. Only of these effects was replicated; the presence of a mental number line. From each of the language tasks, a spatial grounding sensitivity score was calculated based on the difference in reaction times between incongruent and congruent trials. These sensitivity scores were then correlated to performance on the spatial tasks. The results showed almost no significant correlations between the language tasks and spatial tasks, even when looking at those individuals who were most highly sensitive to spatial grounding. Overall the results of this study do not support an embodied view of cognition.
Open Access
Investigating the Relationship Between Social and Spatial Cognitive Maps in Humans
(2021-07-22) Parmar, Jassleen; Iaria, Giuseppe; Lee, Kibeom; Ellard, John; Godley, Jenny
The present study aimed to understand the relationship between social and spatial cognitive maps. Speculation on Tolman’s original idea of a cognitive map suggests that cognitive maps are not exclusive to physical spaces and may instead include social spaces as well. Participants completed 5 social questionnaires, as well as 5 spatial tasks and the Santa Barbara Sense of Direction Scale. The results showed that participants who had more social competence, social capital, social support, and extraversion perceived themselves to be better at spatially navigating. However, their correlations with the objective spatial tasks showed that they were instead significantly poor at spatially navigating, but the effects were small. There was some discrepancy between the subjective and objective tasks and questionnaires. Overall, the results of this study show that there is a negative relationship between spatial navigation and the social questionnaires used.
Open Access
A network neuroscience approach to Developmental Topographical Disorientation
(2022-08-31) Faryadras, Mahsa; Davidsen, Joern; Iaria, Giuseppe; Towlson, Emma; Jackel, Brian
Despite a decade-long study on Developmental Topographical Disorientation (DTD), the underlying mechanism behind this neurological condition remains unknown. This lifelong selective inability in orientation, which causes these individuals to get lost even in familiar surroundings, is present in the absence of any other neurological disorder or acquired brain damage. Herein, we report an analysis of the functional brain network of individuals with DTD (n = 19) compared against that of healthy controls (n = 21), all of whom underwent resting state fMRI, to identify if and how their underlying functional brain network is altered. While the established resting state networks are confirmed in both groups, there is on average a greater connectivity and connectivity strength, in addition to increased global and local efficiency in the overall functional network of the DTD group. In particular, there is an enhanced connectivity between some resting state networks facilitated through indirect functional paths. We identify a handful of nodes that encode part of these differences. Overall, our findings provide strong evidence that the brain networks of individuals suffering from DTD are modified by compensatory mechanisms, which might open the door for new diagnostic tools.
Open Access
Neural Network Dynamics and Efficiency Underlying Individual Variability in Spatial Orientation
(2012-09-24) Arnold, Aiden EGF; Iaria, Giuseppe
Spatial orientation is a complex human skill that exhibits a high degree of individual variability. Here, a neural network perspective is applied to delineate the neural basis of this variability. Using a task that isolates the orientation process from spatial navigation, two sources of neural network variability were found to relate to accurate performance in making orientation decisions – network configuration and efficiency. Participants who preferentially recruited the right Supramarginal Gyrus within a task-related network performed better on the task. Global efficiency in a task-related and whole brain network were also found to relate to performance. These results are presented in a tentative model where the underlying functional architecture of a right lateralized anatomical network influences a person’s ability to configure brain networks associated with spatial orientation. The implications of this model are discussed in the context of neurodegenerative disorders and how it can be used in clinical settings.
Open Access
Neural network dynamics during the generation and reinstatement of mnemonic representations
(2017) Arnold, Aiden; Iaria, Giuseppe; Pexman, Penelope Marion; Protzner, Andrea; Davidsen, Joern Alfred; Rosenbaum, Shayna
The capacity to generate, reinstate, and mentally simulate mnemonic representations is a fundamental aspect of the human mind. It allows us to internally experience other places and moments of time, abstracting away from the present moment into past experiences or hypothetical future states of the world. Theoretical models posit that this capacity is afforded by a neural network distributed across the brain that codes features from our environment and experiences into neural representations that can be reinstated or flexibly combined in a goal oriented manner. Central to this network is the hippocampus, a region of the medial temporal lobes that putatively indexes both the spatial composition of a mental scene and the pattern of hippocampal-cortical interactions that represent feature details. Despite decades of research on hippocampal function during memory processes, our understanding of how this neural network operates dynamically remains limited. This thesis aim to assist in resolving this by investigating patterns of network reconfiguration that occur as a mnemonic representation of a virtual city is generated and reinstated to guide mental simulations of movement through the city. Chapter 2 provides evidence for a general encoding mechanism where the brain transitions from a state of information integration to localized processing based on encoding demands. These results are extended by showing that the hippocampus demonstrates flexibility in how it interacts with other brain regions to actively reinstate and bind features into a holistic representation that is used for mentally simulating movement. Chapter 3 investigates regional effects associated with the task as a validity check. Chapter 4 uses network reconfiguration processes to show that the default mode network, a putative task-negative system, also demonstrates flexibility by altering the functional interactions between its components and regions of the mental simulation network to facilitate feature integration during mnemonic reinstatement. Collectively, these results provide a schematic for extending existing theoretical models on memory function into a dynamic perspective based on the adaptability of neural networks and the flexibility of network components to alter patterns of functional interactions across the brain to process information in a contextual, goal oriented manner.
Open Access
A novel training program for improving spatial orientation: A pilot study
(2019-10-15) McLaren-Gradinaru, Michael; Iaria, Giuseppe; Callahan, Brandy L.; Lévy, Richard M.
The ability to form and use a mental representation of the surrounding is a critical skill for efficient spatial navigation and orientation in humans. Such a mental representation, more commonly known as a “cognitive map”, provides detailed information about landmarks and their relationships with each other in space. The inability to effectively form or use cognitive maps is typically compensated by using lower-level, less efficient approaches to navigation and orientation such as memorizing a series of turns and distances that leads to struggles with navigating the environment, making day-to-day activities more difficult. This study aims to examine the potential to train the ability to form cognitive maps by using a computerized program in a virtual environment designed appositely to simulate the acquisition of this important skill as occurring in children during development. Fifteen healthy adults completed a 12-day training and were administered a comprehensive spatial behavioral assessment before and after the training program. The results showed that the training program significantly improved the participants’ general ability to form cognitive maps. The training program did not significantly improve more specific cognitive functions such as mental rotation and perspective taking, suggesting that the program targets specifically the higher cognitive ability to form a mental representation of the surrounding. These findings provide the very first evidence that the ability to form cognitive map for orientation and navigation is a trainable skill. The use of the novel training program developed for this study could have a significant positive impact in the lives of the many individuals affected by topographical disorientation as a result of a neurological condition or a cognitive decline in the aging population.
Open Access
Simulating Semantics: What Individual Differences in Motor Imagery Can Tell Us About Language Processing
(2020-06-05) Muraki, Emiko Joanne; Pexman, Penny M.; Curtin, Suzanne; Iaria, Giuseppe; Peters, Ryan M.
Over the last 20 years there has been substantial debate and progress towards understanding how cognition may be embodied and, specific to language processing, how multimodal systems may support semantic representation. Despite this progress, the actual processes and mechanisms of modal simulations that are engaged during semantic processing have been under-specified in most theories. In my thesis research, I address this by investigating whether motor imagery ability is related to language processing, with an individual differences approach. Using a combination of implicit and explicit motor imagery tasks and questionnaires, I identified two latent factors that represent individual motor imagery ability and examined whether these factors could account for significant variation in response time during three different language tasks: a lexical decision task, syntactic classification task, and sentence-picture verification task. There were no significant relationships between imagery ability and response time in any of the tasks, however a number of previously reported effects were replicated, most notably the body-object interaction effect, with words higher in body-object interaction (and thus associated with more sensorimotor information) processed more quickly than words low in body-object interaction. While the results suggest that individual differences in motor imagery cannot account for differences in semantic processing, there is still much to learn about the underlying mechanisms of modal simulations proposed by embodied theories of cognition and their relationship to motor imagery.
Open Access
The Clinical Utility of a Computerized Cognitive Assessment to Predict Incident Amnestic Mild Cognitive Impairment and Alzheimer’s Disease
(2023-08-09) Docteur, Natalia Gabriela; Callahan, Brandy; Ismail, Zahinoor; Iaria, Giuseppe
Detecting the initial signs of neurodegeneration is integral for early diagnosis and intervention. Computerized cognitive assessments are accessible, efficient, and precise tools for identifying cognitive impairment and risk of neurodegeneration. While computerized instruments can be feasibly administered repeatedly for longitudinal cognitive monitoring, their clinical utility compared to conventional paper-and-pencil tools is yet unknown. The present study examined the utility of a computerized task, the One Card Learning (OCL) test, to detect conversion to dementia and associate with amyloid (Aβ) imaging markers using single and repeated test administration compared to the Montreal Cognitive Assessment (MoCA) and Rey Auditory Verbal Learning Test (RAVLT). The primary and secondary outcomes were conversion from cognitively normal (CN) to amnestic mild cognitive impairment (aMCI) or Alzheimer’s disease (AD) over a four-year study period and positron emission tomography estimates of Aβ, respectively. Data were collected from the Alzheimer’s Disease Neuroimaging Initiative 3 longitudinal cohort study. Participants were older adults aged 56 to 98 years who were CN at baseline. Results showed that the OCL did not better predict conversion to aMCI or AD from cognitive health compared to the MoCA or RAVLT when assessed at baseline or over repeated administrations. Unadjusted baseline OCL performance associated with Aβ status comparably to the MoCA and RAVLT. While repeated MoCA scores provided the strongest estimate of Aβ accumulation, OCL score trajectories uniquely detected diminished practice effects associated with pathological Aβ accumulation. The OCL may offer distinct clinical utility to detect preclinical AD biomarker accumulation. Future research is needed to examine the application of computerized assessments before they are fully integrated into clinical practice.
Open Access
The Cognitive, Behavioural, and Neural Effects of Environmental Complexity During Navigation
(2016) Slone, Edward; Iaria, Giuseppe; Pexman, Penny; Levy, Richard
A variety of factors combine to determine the outcome of a navigational scenario. Age, sex, and strategy preference, for example, have quantitative and qualitative influences on how an individual is able to find their way in the environment. However, the structure of the environment itself also plays a critical role. Some environments are easier to understand and navigate than others, but it is not always clear why this is the case. The complexity of the environment appears to be an important determinant of navigational success, bur it is notoriously difficult to define and systematically assess its behavioural consequences. In a series of studies, I provide evidence showing that the complexity of the environment not only affects behaviour and cognition, but also activity in several brain regions that are important for navigation. Chapter 2 describes a behavioural study in which participants performed a navigation task in one simple and one complex virtual environment. Navigation in the complex environment was slower and more error prone, and maps drawn of the complex environment were less accurate, suggesting that complexity makes it difficult to form an accurate cognitive map. Chapter 3 describes an experiment in which participants performed the same task while their brain activity was being assessed using functional magnetic resonance imaging. Navigation in the simple environment was associated with increased brain activity in a number of regions, including the precuneus, retrosplenial cortex, hippocampus, and dorsolateral prefrontal cortex. Chapter 4 describes a series of functional connectivity analyses that characterized how the different regions of the brain identified in Chapter 3 altered their dynamic functional properties measured during the task and at rest. Together, these studies suggest that complexity exerts a powerful influence over cognition, behaviour, and brain activity during navigation.