@article{pmid31978550b,

title = {Opposing effects of cortisol on learning and memory in children using spatial versus response-dependent navigation strategies},

author = {Caroll-Ann Blanchette and Vanessa Kurdi and Celine Fouquet and Russell Schachar and Michel Boivin and Paul Hastings and Philippe Robaey and Greg L West and Veronique D Bohbot},

doi = {10.1016/j.nlm.2020.107172},

issn = {1095-9564},

year  = {2020},

date = {2020-03-01},

journal = {Neurobiol Learn Mem},

volume = {169},

pages = {107172},

abstract = {Previous studies showed that healthy young adults who spontaneously use caudate nucleus-dependent strategies on a virtual navigation task, have significantly lower basal levels of cortisol compared with adults who use hippocampus-dependent spatial navigation strategies. In the current paper, we assessed the relation between basal cortisol levels and learning using a virtual navigation task in children. We show that basal cortisol level has a differential effect on learning and memory between children using spatial and response navigation strategies. Specifically, cortisol was found to be beneficial for learning performance in children using spatial strategies, such that higher levels of cortisol were associated with more efficient learning in a virtual maze. In contrast, cortisol had a deleterious effect on learning the virtual maze in children using response strategies, such that higher cortisol levels were associated with increased spatial working memory errors. Based on these results, individual differences in navigation strategy could help explain contradictory results in the literature showing that cortisol can have either a positive or negative association with learning and memory performance.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31203022,

title = {Increased flanker task and forward digit span performance in caudate-nucleus-dependent response strategies},

author = {Étienne Aumont and Martin Arguin and Véronique Bohbot and Greg L West},

doi = {10.1016/j.bandc.2019.05.014},

issn = {1090-2147},

year  = {2019},

date = {2019-10-01},

journal = {Brain Cogn},

volume = {135},

pages = {103576},

abstract = {One of two memory systems can be used to navigate in a new environment. Hippocampus-dependent spatial strategy consists of creating a cognitive map of an environment and caudate nucleus-dependent response strategy consists of memorizing a rigid sequence of turns. Spontaneous use of the response strategy is associated with greater activity and grey matter within the caudate nucleus while the spatial strategy is associated with greater activity and grey matter in the hippocampus. The caudate nucleus is involved in executive functions such as working memory, cognitive control and certain aspects of attention such as attentional disengaging. This study therefore aimed to investigate whether response learners would display better performance on tests of executive and attention functioning compared to spatial learners. Fifty participants completed the 4/8 virtual maze to assess navigational strategy, the forward and backward visual digit span and the Attention Network Test - Revised to assess both attention disengagement and cognitive control. Results revealed that response learners showed significantly higher working memory capacity, more efficient attention disengagement and better cognitive control. Results suggest that response learners, who putatively display more grey matter and activity in the caudate nucleus, are associated with better working memory span, cognitive control and attentional disengagement.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31203022b,

title = {Increased flanker task and forward digit span performance in caudate-nucleus-dependent response strategies},

author = {Étienne Aumont and Martin Arguin and Véronique Bohbot and Greg L West},

doi = {10.1016/j.bandc.2019.05.014},

issn = {1090-2147},

year  = {2019},

date = {2019-10-01},

journal = {Brain Cogn},

volume = {135},

pages = {103576},

abstract = {One of two memory systems can be used to navigate in a new environment. Hippocampus-dependent spatial strategy consists of creating a cognitive map of an environment and caudate nucleus-dependent response strategy consists of memorizing a rigid sequence of turns. Spontaneous use of the response strategy is associated with greater activity and grey matter within the caudate nucleus while the spatial strategy is associated with greater activity and grey matter in the hippocampus. The caudate nucleus is involved in executive functions such as working memory, cognitive control and certain aspects of attention such as attentional disengaging. This study therefore aimed to investigate whether response learners would display better performance on tests of executive and attention functioning compared to spatial learners. Fifty participants completed the 4/8 virtual maze to assess navigational strategy, the forward and backward visual digit span and the Attention Network Test - Revised to assess both attention disengagement and cognitive control. Results revealed that response learners showed significantly higher working memory capacity, more efficient attention disengagement and better cognitive control. Results suggest that response learners, who putatively display more grey matter and activity in the caudate nucleus, are associated with better working memory span, cognitive control and attentional disengagement.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31174032b,

title = {Spontaneous spatial navigation circuitry in schizophrenia spectrum disorders},

author = {Leanne K Wilkins and Todd A Girard and Bruce K Christensen and Jelena King and Michael Kiang and Veronique D Bohbot},

doi = {10.1016/j.psychres.2019.05.032},

issn = {1872-7123},

year  = {2019},

date = {2019-08-01},

journal = {Psychiatry Res},

volume = {278},

pages = {125--128},

abstract = {Spatial memory is core to wayfinding and everyday memory. Interestingly, individuals with schizophrenia using spatial navigation strategies (cognitive mapping) are impaired, whereas those using response-based (e.g., single-landmark) strategies show relatively intact memory performance. We observed abnormal brain communication in schizophrenia participants who used a spatial strategy during a virtual-reality navigation task, particularly between temporal and frontal brain regions. In contrast, schizophrenia participants using a response strategy recruited similar brain systems to healthy participants, but to a greater extent to support memory performance. These findings highlight that strategy use is an important consideration for understanding memory systems and navigation in schizophrenia.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid31174032,

title = {Spontaneous spatial navigation circuitry in schizophrenia spectrum disorders},

author = {Leanne K Wilkins and Todd A Girard and Bruce K Christensen and Jelena King and Michael Kiang and Veronique D Bohbot},

doi = {10.1016/j.psychres.2019.05.032},

issn = {1872-7123},

year  = {2019},

date = {2019-08-01},

journal = {Psychiatry Res},

volume = {278},

pages = {125--128},

abstract = {Spatial memory is core to wayfinding and everyday memory. Interestingly, individuals with schizophrenia using spatial navigation strategies (cognitive mapping) are impaired, whereas those using response-based (e.g., single-landmark) strategies show relatively intact memory performance. We observed abnormal brain communication in schizophrenia participants who used a spatial strategy during a virtual-reality navigation task, particularly between temporal and frontal brain regions. In contrast, schizophrenia participants using a response strategy recruited similar brain systems to healthy participants, but to a greater extent to support memory performance. These findings highlight that strategy use is an important consideration for understanding memory systems and navigation in schizophrenia.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid30898972b,

title = {Caudate nucleus-dependent navigation strategies are associated with increased risk-taking and set-shifting behavior},

author = {Étienne Aumont and Caroll-Ann Blanchette and Veronique D Bohbot and Greg L West},

doi = {10.1101/lm.048306.118},

issn = {1549-5485},

year  = {2019},

date = {2019-04-01},

journal = {Learn Mem},

volume = {26},

number = {4},

pages = {101--108},

abstract = {When people navigate, they use strategies dependent on one of two memory systems. The hippocampus-based spatial strategy consists of using multiple landmarks to create a cognitive map of the environment. In contrast, the caudate nucleus-based response strategy is based on the memorization of a series of turns. Importantly, response learners display more gray matter and functional activity in the caudate nucleus and less gray matter in the hippocampus. In parallel, the caudate nucleus is involved in decision-making by mediating attention toward rewards and in set-shifting by mediating preparatory actions. The present study, therefore, examined the link between navigational strategy use, that are associated with gray matter differences in the caudate nucleus and hippocampus, and decision-making and set-shifting performance. Fifty-three participants completed the 4 on 8 virtual maze, the Iowa Gambling Task (IGT), the Wisconsin Card Sorting Test-64 (WCST-64), and a task-switching test. The results revealed that people who use response strategies displayed increased risk-taking behavior in the IGT compared to the people using hippocampus-dependent spatial strategies. Response strategy was also associated with enhanced set-shifting performance in the WCST-64 and task-switching test. These results confirm that risk-taking and set-shifting behavior, that are differentially impacted by the caudate nucleus and hippocampus memory systems, can be predicted by navigational strategy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid30898972,

title = {Caudate nucleus-dependent navigation strategies are associated with increased risk-taking and set-shifting behavior},

author = {Étienne Aumont and Caroll-Ann Blanchette and Veronique D Bohbot and Greg L West},

doi = {10.1101/lm.048306.118},

issn = {1549-5485},

year  = {2019},

date = {2019-04-01},

journal = {Learn Mem},

volume = {26},

number = {4},

pages = {101--108},

abstract = {When people navigate, they use strategies dependent on one of two memory systems. The hippocampus-based spatial strategy consists of using multiple landmarks to create a cognitive map of the environment. In contrast, the caudate nucleus-based response strategy is based on the memorization of a series of turns. Importantly, response learners display more gray matter and functional activity in the caudate nucleus and less gray matter in the hippocampus. In parallel, the caudate nucleus is involved in decision-making by mediating attention toward rewards and in set-shifting by mediating preparatory actions. The present study, therefore, examined the link between navigational strategy use, that are associated with gray matter differences in the caudate nucleus and hippocampus, and decision-making and set-shifting performance. Fifty-three participants completed the 4 on 8 virtual maze, the Iowa Gambling Task (IGT), the Wisconsin Card Sorting Test-64 (WCST-64), and a task-switching test. The results revealed that people who use response strategies displayed increased risk-taking behavior in the IGT compared to the people using hippocampus-dependent spatial strategies. Response strategy was also associated with enhanced set-shifting performance in the WCST-64 and task-switching test. These results confirm that risk-taking and set-shifting behavior, that are differentially impacted by the caudate nucleus and hippocampus memory systems, can be predicted by navigational strategy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid30294869b,

title = {Autistic traits in neurotypical individuals are associated with increased landmark use during navigation},

author = {Caroll-Ann Blanchette and Jamila Amirova and Veronique D Bohbot and Greg L West},

doi = {10.1002/pchj.230},

issn = {2046-0260},

year  = {2019},

date = {2019-03-01},

journal = {Psych J},

volume = {8},

number = {1},

pages = {137--146},

abstract = {People adopt two distinct learning strategies during navigation. "Spatial learners" navigate by building a cognitive map using environmental landmarks, and display more grey matter in the hippocampus. Conversely, "response learners" memorize a series of rigid turns to navigate and display more grey matter in the caudate nucleus of the striatum. Evidence has linked these two structures with autism spectrum disorder (ASD) and autistic traits in non-clinical populations. Both people with ASD and neurotypical people with higher levels of autistic traits have been shown to display more grey matter in the hippocampus and less functional activity in the caudate nucleus. We therefore tested 56 healthy participants who completed the Autism Quotient (AQ) Scale and the 4-on-8 Virtual Maze (4/8 VM), which determines the reliance on landmarks during navigation. We found that people who relied on landmarks during navigation also displayed significantly higher scores on the AQ Scale. Because spatial strategies are associated with increased attention to environmental landmark use and are supported by the hippocampus, our results provide a potential behavioral mechanism linking higher autistic traits (e.g., increased attention to detail and increased sensory processes) to increased hippocampal grey matter.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid30294869,

title = {Autistic traits in neurotypical individuals are associated with increased landmark use during navigation},

author = {Caroll-Ann Blanchette and Jamila Amirova and Veronique D Bohbot and Greg L West},

doi = {10.1002/pchj.230},

issn = {2046-0260},

year  = {2019},

date = {2019-03-01},

journal = {Psych J},

volume = {8},

number = {1},

pages = {137--146},

abstract = {People adopt two distinct learning strategies during navigation. "Spatial learners" navigate by building a cognitive map using environmental landmarks, and display more grey matter in the hippocampus. Conversely, "response learners" memorize a series of rigid turns to navigate and display more grey matter in the caudate nucleus of the striatum. Evidence has linked these two structures with autism spectrum disorder (ASD) and autistic traits in non-clinical populations. Both people with ASD and neurotypical people with higher levels of autistic traits have been shown to display more grey matter in the hippocampus and less functional activity in the caudate nucleus. We therefore tested 56 healthy participants who completed the Autism Quotient (AQ) Scale and the 4-on-8 Virtual Maze (4/8 VM), which determines the reliance on landmarks during navigation. We found that people who relied on landmarks during navigation also displayed significantly higher scores on the AQ Scale. Because spatial strategies are associated with increased attention to environmental landmark use and are supported by the hippocampus, our results provide a potential behavioral mechanism linking higher autistic traits (e.g., increased attention to detail and increased sensory processes) to increased hippocampal grey matter.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32009912,

title = {Fimbria-Fornix Volume Is Associated With Spatial Memory and Olfactory Identification in Humans},

author = {Louisa Dahmani and Blandine Courcot and Jamie Near and Raihaan Patel and Robert S C Amaral and M Mallar Chakravarty and Véronique D Bohbot},

doi = {10.3389/fnsys.2019.00087},

issn = {1662-5137},

year  = {2019},

date = {2019-01-01},

journal = {Front Syst Neurosci},

volume = {13},

pages = {87},

abstract = {White matter pathways that surround the hippocampus comprise its afferent and efferent connections, and are therefore crucial in mediating the function of the hippocampus. We recently demonstrated a role for the hippocampus in both spatial memory and olfactory identification in humans. In the current study, we focused our attention on the fimbria-fornix white matter bundle and investigated its relationship with spatial memory and olfactory identification. We administered a virtual navigation task and an olfactory identification task to 55 young healthy adults and measured the volume of the fimbria-fornix. We found that the volume of the right fimbria-fornix and its subdivisions is correlated with both navigational learning and olfactory identification in those who use hippocampus-based spatial memory strategies, and not in those who use caudate nucleus-based navigation strategies. These results are consistent with our recent finding that spatial memory and olfaction rely on similar neural networks and structures.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid32009912b,

title = {Fimbria-Fornix Volume Is Associated With Spatial Memory and Olfactory Identification in Humans},

author = {Louisa Dahmani and Blandine Courcot and Jamie Near and Raihaan Patel and Robert S C Amaral and M Mallar Chakravarty and Véronique D Bohbot},

doi = {10.3389/fnsys.2019.00087},

issn = {1662-5137},

year  = {2019},

date = {2019-01-01},

journal = {Front Syst Neurosci},

volume = {13},

pages = {87},

abstract = {White matter pathways that surround the hippocampus comprise its afferent and efferent connections, and are therefore crucial in mediating the function of the hippocampus. We recently demonstrated a role for the hippocampus in both spatial memory and olfactory identification in humans. In the current study, we focused our attention on the fimbria-fornix white matter bundle and investigated its relationship with spatial memory and olfactory identification. We administered a virtual navigation task and an olfactory identification task to 55 young healthy adults and measured the volume of the fimbria-fornix. We found that the volume of the right fimbria-fornix and its subdivisions is correlated with both navigational learning and olfactory identification in those who use hippocampus-based spatial memory strategies, and not in those who use caudate nucleus-based navigation strategies. These results are consistent with our recent finding that spatial memory and olfaction rely on similar neural networks and structures.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid30327469b,

title = {An intrinsic association between olfactory identification and spatial memory in humans},

author = {Louisa Dahmani and Raihaan M Patel and Yiling Yang and M Mallar Chakravarty and Lesley K Fellows and Véronique D Bohbot},

doi = {10.1038/s41467-018-06569-4},

issn = {2041-1723},

year  = {2018},

date = {2018-10-01},

journal = {Nat Commun},

volume = {9},

number = {1},

pages = {4162},

abstract = {It was recently proposed that olfaction evolved to aid navigation. Consistent with this hypothesis, olfactory identification and spatial memory are linked to overlapping brain areas which include the orbitofrontal cortex and hippocampus. However, the relationship between these two processes has never been specifically investigated. Here, we show that olfactory identification covaries with spatial memory in humans. We also found that the cortical thickness of the left medial orbitofrontal cortex, and the volume of the right hippocampus, predict both olfactory identification and spatial memory. Finally, we demonstrate deficits in both olfactory identification and spatial memory in patients with lesions of the medial orbitofrontal cortex. Our findings reveal an intrinsic relationship between olfaction and spatial memory that is supported by a shared reliance on the hippocampus and medial orbitofrontal cortex. This relationship may find its roots in the parallel evolution of the olfactory and hippocampal systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid30327469,

title = {An intrinsic association between olfactory identification and spatial memory in humans},

author = {Louisa Dahmani and Raihaan M Patel and Yiling Yang and M Mallar Chakravarty and Lesley K Fellows and Véronique D Bohbot},

doi = {10.1038/s41467-018-06569-4},

issn = {2041-1723},

year  = {2018},

date = {2018-10-01},

journal = {Nat Commun},

volume = {9},

number = {1},

pages = {4162},

abstract = {It was recently proposed that olfaction evolved to aid navigation. Consistent with this hypothesis, olfactory identification and spatial memory are linked to overlapping brain areas which include the orbitofrontal cortex and hippocampus. However, the relationship between these two processes has never been specifically investigated. Here, we show that olfactory identification covaries with spatial memory in humans. We also found that the cortical thickness of the left medial orbitofrontal cortex, and the volume of the right hippocampus, predict both olfactory identification and spatial memory. Finally, we demonstrate deficits in both olfactory identification and spatial memory in patients with lesions of the medial orbitofrontal cortex. Our findings reveal an intrinsic relationship between olfaction and spatial memory that is supported by a shared reliance on the hippocampus and medial orbitofrontal cortex. This relationship may find its roots in the parallel evolution of the olfactory and hippocampal systems.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid30100340b,

title = {Global Determinants of Navigation Ability},

author = {Antoine Coutrot and Ricardo Silva and Ed Manley and Will de Cothi and Saber Sami and Véronique D Bohbot and Jan M Wiener and Christoph Hölscher and Ruth C Dalton and Michael Hornberger and Hugo J Spiers},

doi = {10.1016/j.cub.2018.06.009},

issn = {1879-0445},

year  = {2018},

date = {2018-09-01},

journal = {Curr Biol},

volume = {28},

number = {17},

pages = {2861--2866.e4},

abstract = {Human spatial ability is modulated by a number of factors, including age [1-3] and gender [4, 5]. Although a few studies showed that culture influences cognitive strategies [6-13], the interaction between these factors has never been globally assessed as this requires testing millions of people of all ages across many different countries in the world. Since countries vary in their geographical and cultural properties, we predicted that these variations give rise to an organized spatial distribution of cognition at a planetary-wide scale. To test this hypothesis, we developed a mobile-app-based cognitive task, measuring non-verbal spatial navigation ability in more than 2.5 million people and sampling populations in every nation state. We focused on spatial navigation due to its universal requirement across cultures. Using a clustering approach, we find that navigation ability is clustered into five distinct, yet geographically related, groups of countries. Specifically, the economic wealth of a nation was predictive of the average navigation ability of its inhabitants, and gender inequality was predictive of the size of performance difference between males and females. Thus, cognitive abilities, at least for spatial navigation, are clustered according to economic wealth and gender inequalities globally, which has significant implications for cross-cultural studies and multi-center clinical trials using cognitive testing.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid30100340,

title = {Global Determinants of Navigation Ability},

author = {Antoine Coutrot and Ricardo Silva and Ed Manley and Will de Cothi and Saber Sami and Véronique D Bohbot and Jan M Wiener and Christoph Hölscher and Ruth C Dalton and Michael Hornberger and Hugo J Spiers},

doi = {10.1016/j.cub.2018.06.009},

issn = {1879-0445},

year  = {2018},

date = {2018-09-01},

journal = {Curr Biol},

volume = {28},

number = {17},

pages = {2861--2866.e4},

abstract = {Human spatial ability is modulated by a number of factors, including age [1-3] and gender [4, 5]. Although a few studies showed that culture influences cognitive strategies [6-13], the interaction between these factors has never been globally assessed as this requires testing millions of people of all ages across many different countries in the world. Since countries vary in their geographical and cultural properties, we predicted that these variations give rise to an organized spatial distribution of cognition at a planetary-wide scale. To test this hypothesis, we developed a mobile-app-based cognitive task, measuring non-verbal spatial navigation ability in more than 2.5 million people and sampling populations in every nation state. We focused on spatial navigation due to its universal requirement across cultures. Using a clustering approach, we find that navigation ability is clustered into five distinct, yet geographically related, groups of countries. Specifically, the economic wealth of a nation was predictive of the average navigation ability of its inhabitants, and gender inequality was predictive of the size of performance difference between males and females. Thus, cognitive abilities, at least for spatial navigation, are clustered according to economic wealth and gender inequalities globally, which has significant implications for cross-cultural studies and multi-center clinical trials using cognitive testing.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid29461337,

title = {Habitual action video game players display increased cortical thickness in the dorsal anterior cingulate cortex},

author = {Jessica Benady-Chorney and Yvonne Yau and Yashar Zeighami and Veronique D Bohbot and Greg L West},

doi = {10.1097/WNR.0000000000000981},

issn = {1473-558X},

year  = {2018},

date = {2018-03-01},

journal = {Neuroreport},

volume = {29},

number = {5},

pages = {393--396},

abstract = {Action video game players (aVGPs) display increased performance in attention-based tasks and enhanced procedural motor learning. In parallel, the anterior cingulate cortex (ACC) is centrally implicated in specific types of reward-based learning and attentional control, the execution or inhibition of motor commands, and error detection. These processes are hypothesized to support aVGP in-game performance and enhanced learning though in-game feedback. We, therefore, tested the hypothesis that habitual aVGPs would display increased cortical thickness compared with nonvideo game players (nonVGPs). Results showed that the aVGP group (n=17) displayed significantly higher levels of cortical thickness specifically in the dorsal ACC compared with the nonVGP group (n=16). Results are discussed in the context of previous findings examining video game experience, attention/performance, and responses to affective components such as pain and fear.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid29278888,

title = {Healthy versus Entorhinal Cortical Atrophy Identification in Asymptomatic APOE4 Carriers at Risk for Alzheimer's Disease},

author = {Kyoko Konishi and Ridha Joober and Judes Poirier and Kathleen MacDonald and Mallar Chakravarty and Raihaan Patel and John Breitner and Véronique D Bohbot},

doi = {10.3233/JAD-170540},

issn = {1875-8908},

year  = {2018},

date = {2018-01-01},

journal = {J Alzheimers Dis},

volume = {61},

number = {4},

pages = {1493--1507},

abstract = {Early detection of Alzheimer's disease (AD) has been challenging as current biomarkers are invasive and costly. Strong predictors of future AD diagnosis include lower volume of the hippocampus and entorhinal cortex, as well as the ɛ4 allele of the Apolipoprotein E gene (APOE) gene. Therefore, studying functions that are critically mediated by the hippocampus and entorhinal cortex, such as spatial memory, in APOE ɛ4 allele carriers, may be key to the identification of individuals at risk of AD, prior to the manifestation of cognitive impairments. Using a virtual navigation task developed in-house, specifically designed to assess spatial versus non-spatial strategies, the current study is the first to differentiate functional and structural differences within APOE ɛ4 allele carriers. APOE ɛ4 allele carriers that predominantly use non-spatial strategies have decreased fMRI activity in the hippocampus and increased atrophy in the hippocampus, entorhinal cortex, and fimbria compared to APOE ɛ4 allele carriers who use spatial strategies. In contrast, APOE ɛ4 allele carriers who use spatial strategies have grey matter levels comparable to non-APOE ɛ4 allele carriers. Furthermore, in a leave-one-out analysis, grey matter in the entorhinal cortex could predict navigational strategy with 92% accuracy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid28963056,

title = {Hippocampus-dependent spatial learning is associated with higher global cognition among healthy older adults},

author = {Kyoko Konishi and Sam Mckenzie and Nicole Etchamendy and Shumita Roy and Véronique D Bohbot},

doi = {10.1016/j.neuropsychologia.2017.09.025},

issn = {1873-3514},

year  = {2017},

date = {2017-11-01},

journal = {Neuropsychologia},

volume = {106},

pages = {310--321},

abstract = {Cognitive deficits in normal aging have been associated with atrophy of the hippocampus. As such, methods to detect early dysfunction of the hippocampus have become valuable, if not indispensable, to early intervention. The hippocampus is critical for spatial memory and is among the first structures to atrophy with aging. Despite the presence of navigation deficits in aging, few studies have looked at the association between wayfinding ability, navigation strategies, general cognitive function, and hippocampal volume. In the current study we investigated whether better general cognitive function is associated with the use of hippocampal-dependent spatial strategies, better spatial memory, and increased hippocampal volume. We also investigated, within older adults, the effects of aging on spatial memory. Healthy older adults (N = 107) were tested on a virtual wayfinding task and a dual-solution navigation task that can be solved using either a hippocampal-dependent spatial strategy or a caudate nucleus-dependent response strategy. Participants were also administered the Montreal Cognitive Assessment (MoCA), a test that measures general cognition and is sensitive to dementia. A structural MRI was administered to a sub-set of participants (n = 49) and hippocampal volume was calculated using a Multiple Automatically Generated Templates (MAGeT) Brain algorithm. We found that age was negatively associated with wayfinding ability and hippocampal volume. On the wayfinding task, participants with higher MoCA scores found more target locations and travelled shorter distances. We also found a significant association between higher MoCA scores and spatial strategy use. MoCA scores, spatial memory ability, and spatial strategy use all positively correlated with a larger hippocampal volume. These results confirm that with age there is a decrease in spatial memory, which is consistent with decreased volume in the hippocampus with aging. Furthermore, better general cognitive function is associated with better wayfinding ability and increased use of hippocampal-dependent spatial strategies.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid28780430,

title = {Hippocampal activation and memory performance in schizophrenia depend on strategy use in a virtual maze},

author = {Leanne K Wilkins and Todd A Girard and Katherine A Herdman and Bruce K Christensen and Jelena King and Michael Kiang and Veronique D Bohbot},

doi = {10.1016/j.pscychresns.2017.07.007},

issn = {1872-7506},

year  = {2017},

date = {2017-10-01},

journal = {Psychiatry Res Neuroimaging},

volume = {268},

pages = {1--8},

abstract = {Different strategies may be spontaneously adopted to solve most navigation tasks. These strategies are associated with dissociable brain systems. Here, we use brain-imaging and cognitive tasks to test the hypothesis that individuals living with Schizophrenia Spectrum Disorders (SSD) have selective impairment using a hippocampal-dependent spatial navigation strategy. Brain activation and memory performance were examined using functional magnetic resonance imaging (fMRI) during the 4-on-8 virtual maze (4/8VM) task, a human analog of the rodent radial-arm maze that is amenable to both response-based (egocentric or landmark-based) and spatial (allocentric, cognitive mapping) strategies to remember and navigate to target objects. SSD (schizophrenia and schizoaffective disorder) participants who adopted a spatial strategy performed more poorly on the 4/8VM task and had less hippocampal activation than healthy comparison participants using either strategy as well as SSD participants using a response strategy. This study highlights the importance of strategy use in relation to spatial cognitive functioning in SSD. Consistent with a selective-hippocampal dependent deficit in SSD, these results support the further development of protocols to train impaired hippocampal-dependent abilities or harness non-hippocampal dependent intact abilities.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pmid28394147,

title = {A lower ratio of omega-6 to omega-3 fatty acids predicts better hippocampus-dependent spatial memory and cognitive status in older adults},

author = {Nadia D Andruchow and Kyoko Konishi and Bryna Shatenstein and Véronique D Bohbot},

doi = {10.1037/neu0000373},

issn = {1931-1559},

year  = {2017},

date = {2017-10-01},

journal = {Neuropsychology},

volume = {31},

number = {7},

pages = {724--734},

abstract = {OBJECTIVE: Evidence from several cross-sectional studies indicates that an increase in omega-6 to omega-3 fatty acids (FAs) may negatively affect cognition in old age. The hippocampus is among the first neural structures affected by age and atrophy in this brain region is associated with cognitive decline. Therefore, we hypothesized that a lower omega-6:3 FA ratio would predict better hippocampus-dependent spatial memory, and a higher general cognitive status.nnMETHOD: Fifty-two healthy older adults completed a Food Frequency Questionnaire, the Montreal Cognitive Assessment test (MoCA; a test of global cognition) and virtual navigation tasks that assess navigational strategies and spatial memory.nnRESULTS: In this cross-sectional study, a lower ratio of omega-6 to omega-3 FA intake strongly predicted more accurate hippocampus-dependent spatial memory and faster learning on our virtual navigation tasks, as well as higher cognitive status overall.nnCONCLUSIONS: These results may help elucidate why certain dietary patterns with a lower omega-6:3 FA ratio, like the Mediterranean diet, are associated with reduced risk of cognitive decline. (PsycINFO Database Record},

keywords = {},

pubstate = {published},

tppubtype = {article}

}