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Mohammed, Abdul K. H.
Publications (10 of 21) Show all publications
Ledreux, A., Håkansson, K., Carlsson, R., Tewele, M. K., Columbo, L., Terjestam, Y., . . . Mohammed, A. K. H. (2019). Differential Effects of Physical Exercise, Cognitive Training, and Mindfulness Practice on Serum BDNF Levels in Healthy Older Adults: A Randomized Controlled Intervention Study. Journal of Alzheimer's Disease, 71(4), 1245-1261
Open this publication in new window or tab >>Differential Effects of Physical Exercise, Cognitive Training, and Mindfulness Practice on Serum BDNF Levels in Healthy Older Adults: A Randomized Controlled Intervention Study
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2019 (English)In: Journal of Alzheimer's Disease, ISSN 1387-2877, E-ISSN 1875-8908, Vol. 71, no 4, p. 1245-1261Article in journal (Refereed) Published
Abstract [en]

Previous studies have indicated that an active lifestyle is associated with better brain health and a longer life, compared to a more sedentary lifestyle. These studies, both on human and animal subjects, have typically focused on a single activity, usually physical exercise, but other activities have received an increasing interest. One proposed mechanism is that physical exercise increases levels of brain-derived neurotrophic factor (BDNF) in the brain. For the first time, the long-term effects on serum BDNF levels were compared in persons who engaged in either physical exercise training, cognitive training, or mindfulness practice during 5 weeks, and compared with an active control group. Two cohorts of healthy older individuals, one from the Boston area in the US and one from the Vaxjo area in Sweden, participated. A total of 146 participants were randomly assigned to one of the four groups. All interventions were structurally similar, using interactive, computer-based software that directed participants to carry out specified activities for 35 minutes/day, 5 days per week for 5 weeks. Blood samples were obtained at baseline and soon after the completion of the 5-week long intervention program, and serum BDNF levels were measured using a commercially available ELISA. Only the group that underwent cognitive training increased their serum BDNF levels after 5 weeks of training (F-1,F-74 = 4.22, p = 0.044, partial eta(2) = 0.054), corresponding to an average 10% increase. These results strongly suggest that cognitive training can exert beneficial effects on brain health in an older adult population.

Place, publisher, year, edition, pages
IOS Press, 2019
Keywords
Aging, brain-derived neurotrophic factor, cognitive training, mindfulness, physical exercise
National Category
Psychology
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-89872 (URN)10.3233/JAD-190756 (DOI)000490569300017 ()31498125 (PubMedID)
Available from: 2019-10-31 Created: 2019-10-31 Last updated: 2019-10-31Bibliographically approved
Behforuzi, H., Feng, N. C., Billig, A. R., Ryan, E., Tusch, E. S., Holcomb, P. J., . . . Daffner, K. R. (2019). Markers of Novelty Processing in Older Adults Are Stable and Reliable. Frontiers in Aging Neuroscience, 11, 1-15, Article ID 165.
Open this publication in new window or tab >>Markers of Novelty Processing in Older Adults Are Stable and Reliable
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2019 (English)In: Frontiers in Aging Neuroscience, ISSN 1663-4365, E-ISSN 1663-4365, Vol. 11, p. 1-15, article id 165Article in journal (Refereed) Published
Abstract [en]

Exploratory behavior and responsiveness to novelty play an important role in maintaining cognitive function in older adults. Inferences about age- or disease-related differences in neural and behavioral responses to novelty are most often based on results from single experimental testing sessions. There has been very limited research on whether such findings represent stable characteristics of populations studied, which is essential if investigators are to determine the result of interventions aimed at promoting exploratory behaviors or draw appropriate conclusions about differences in the processing of novelty across diverse clinical groups. The goal of the current study was to investigate the short-term test-retest reliability of event-related potential (ERP) and behavioral responses to novel stimuli in cognitively normal older adults. ERPs and viewing durations were recorded in 70 healthy older adults participating in a subject-controlled visual novelty oddball task during two sessions occurring 7 weeks apart. Mean midline P3 amplitude and latency, mean midline amplitude during successive 50 ms intervals, temporospatial factors derived from principal component analysis (PCA), and viewing duration in response to novel stimuli were measured during each session. Analysis of variance (ANOVA) revealed no reliable differences in the value of any measurements between Time 1 and 2. Intraclass correlation coefficients (ICCs) between Time 1 and 2 were excellent for mean P3 amplitude (ICC = 0.86), the two temporospatial factors consistent with the P3 components (ICC of 0.88 and 0.76) and viewing duration of novel stimuli (ICC = 0.81). Reliability was only fair for P3 peak latency (ICC = 0.56). Successive 50 ms mean amplitude measures from 100 to 1,000 ms yielded fair to excellent reliabilities, and all but one of the 12 temporospatial factors identified demonstrated ICCs in the good to excellent range. We conclude that older adults demonstrate substantial stability in ERP and behavioral responses to novel visual stimuli over a 7-week period. These results suggest that older adults may have a characteristic way of processing novelty that appears resistant to transient changes in their environment or internal states, which can be indexed during a single testing session. The establishment of reliable measures of novelty processing will allow investigators to determine whether proposed interventions have an impact on this important aspect of behavior.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2019
Keywords
ERP, test-retest reliability, aging, novelty processing, visual modality
National Category
Neurology
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-86957 (URN)10.3389/fnagi.2019.00165 (DOI)000473280200002 ()2-s2.0-85069523510 (Scopus ID)
Available from: 2019-07-24 Created: 2019-07-24 Last updated: 2019-08-29Bibliographically approved
Kakooza-Mwesige, A., Mohammed, A. K. H., Kristensson, K., Juliano, S. L. & Lutwama, J. J. (2018). Emerging Viral Infections in Sub-Saharan Africa and the Developing Nervous System: A Mini Review. Frontiers in Neurology, 9, Article ID 82.
Open this publication in new window or tab >>Emerging Viral Infections in Sub-Saharan Africa and the Developing Nervous System: A Mini Review
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2018 (English)In: Frontiers in Neurology, ISSN 1664-2295, E-ISSN 1664-2295, Vol. 9, article id 82Article, review/survey (Refereed) Published
Abstract [en]

The global public health concern is heightened over the increasing number of emerging viruses, i.e., newly discovered or previously known that have expanded into new geographical zones. These viruses challenge the health-care systems in sub-Saharan Africa (SSA) countries from which several of them have originated and been transmitted by insects worldwide. Some of these viruses are neuroinvasive, but have been relatively neglected by neuroscientists. They may provide experiments by nature to give a time window for exposure to a new virus within sizeable, previously non-infected human populations, which, for instance, enables studies on potential long-term or late-onset effects on the developing nervous system. Here, we briefly summarize studies on the developing brain by West Nile, Zika, and Chikungunya viruses, which are mosquito-borne and have spread worldwide out of SSA. They can all be neuroinvasive, but their effects vary from malformations caused by prenatal infections to cognitive disturbances following perinatal or later infections. We also highlight Ebola virus, which can leave surviving children with psychiatric disturbances and cause persistent infections in the non-human primate brain. Greater awareness within the neuroscience community is needed to emphasize the menace evoked by these emerging viruses to the developing brain. In particular, frontline neuroscience research should include neuropediatric follow-up studies in the field on long-term or late-onset cognitive and behavior disturbances or neuropsychiatric disorders. Studies on pathogenetic mechanisms for viral-induced perturbations of brain maturation should be extended to the vulnerable periods when neurocircuit formations are at peaks during infancy and early childhood.

Place, publisher, year, edition, pages
Frontiers Media S.A., 2018
Keywords
developing nervous system, emerging viruses, Ebola virus, Chikungunya virus, West Nile virus, Zika virus, neurological disorders, sub-Saharan Africa
National Category
Microbiology in the medical area Neurosciences
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-71553 (URN)10.3389/fneur.2018.00082 (DOI)000425991700001 ()2-s2.0-85042452816 (Scopus ID)
Available from: 2018-03-16 Created: 2018-03-16 Last updated: 2019-08-29Bibliographically approved
Simon, S. S., Tusch, E. S., Feng, N. C., Håkansson, K., Mohammed, A. K. H. & Daffner, K. R. (2018). Is Computerized Working Memory Training Effective in Healthy Older Adults?: Evidence from a Multi-Site, Randomized Controlled Trial. Journal of Alzheimer's Disease, 65(3), 931-949
Open this publication in new window or tab >>Is Computerized Working Memory Training Effective in Healthy Older Adults?: Evidence from a Multi-Site, Randomized Controlled Trial
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2018 (English)In: Journal of Alzheimer's Disease, ISSN 1387-2877, E-ISSN 1875-8908, Vol. 65, no 3, p. 931-949Article in journal (Refereed) Published
Abstract [en]

Background: Developing effective interventions to attenuate age-related cognitive decline and prevent or delay the onset of dementia are major public health goals. Computerized cognitive training (CCT) has been marketed increasingly to older adults, but its efficacy remains unclear. Working memory (WM), a key determinant of higher order cognitive abilities, is susceptible to age-related decline and a relevant target for CCT in elders. Objective: To evaluate the efficacy of CCT focused on WM compared to an active control condition in healthy older adults. Methods: Eighty-two cognitively normal adults from two sites (USA and Sweden) were randomly assigned to Cogmed Adaptive or Non-Adaptive (active control) CCT groups. Training was performed in participants' homes, five days per week over five weeks. Changes in the performance of the Cogmed trained tasks, and in five neuropsychological tests (Trail Making Test Part A and Part B, Digit Symbol, Controlled Oral Word Association Test and Semantic Fluency) were used as outcome measures. Results: The groups were comparable at baseline. The Adaptive group showed robust gains in the trained tasks, and there was a time-by-group interaction for the Digit Symbol test, with significant improvement only after Adaptive training. In addition, the magnitude of the intervention effect was similar at both sites. Conclusion: Home-based CCT Adaptive WM training appears more effective than Non-Adaptive training in older adults from different cultural backgrounds. We present evidence of improvement in trained tasks and on a demanding untrained task dependent upon WM and processing speed. The benefits over the active control group suggest that the Adaptive CCT gains were linked to providing a continuously challenging level of WM difficulty.

Place, publisher, year, edition, pages
IOS Press, 2018
Keywords
Aging, computerized cognitive training, randomized controlled trial, working memory
National Category
Psychology
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-78427 (URN)10.3233/JAD-180455 (DOI)000444339800018 ()30103334 (PubMedID)2-s2.0-85053717016 (Scopus ID)
Available from: 2018-10-22 Created: 2018-10-22 Last updated: 2019-08-29Bibliographically approved
Håkansson, K., Ledreux, A., Daffner, K., Terjestam, Y., Bergman, P., Carlsson, R., . . . Mohammed, A. K. H. (2017). BDNF Responses in Healthy Older Persons to 35 Minutes of Physical Exercise, Cognitive Training, and Mindfulness: Associations with Working Memory Function. Journal of Alzheimer's Disease, 55(2), 645-657
Open this publication in new window or tab >>BDNF Responses in Healthy Older Persons to 35 Minutes of Physical Exercise, Cognitive Training, and Mindfulness: Associations with Working Memory Function
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2017 (English)In: Journal of Alzheimer's Disease, ISSN 1387-2877, E-ISSN 1875-8908, Vol. 55, no 2, p. 645-657Article in journal (Refereed) Published
Abstract [en]

Brain-derived neurotrophic factor (BDNF) has a central role in brain plasticity by mediating changes in cortical thickness and synaptic density in response to physical activity and environmental enrichment. Previous studies suggest that physical exercise can augment BDNF levels, both in serum and the brain, but no other study has examined how different types of activities compare with physical exercise in their ability to affect BDNF levels. By using a balanced cross over experimental design, we exposed nineteen healthy older adults to 35-minute sessions of physical exercise, cognitive training, and mindfulness practice, and compared the resulting changes in mature BDNF levels between the three activities. We show that a single bout of physical exercise has significantly larger impact on serum BDNF levels than either cognitive training or mindfulness practice in the same persons. This is the first study on immediate BDNF effects of physical activity in older healthy humans and also the first study to demonstrate an association between serum BDNF responsivity to acute physical exercise and working memory function. We conclude that the BDNF increase we found after physical exercise more probably has a peripheral than a central origin, but that the association between post-intervention BDNF levels and cognitive function could have implications for BDNF responsivity in serum as a potential marker of cognitive health.

Place, publisher, year, edition, pages
IOS Press, 2017
National Category
Psychology Neurosciences
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-59565 (URN)10.3233/JAD-160593 (DOI)000389695700018 ()27716670 (PubMedID)2-s2.0-84999114779 (Scopus ID)
Projects
SAGE
Funder
The Kamprad Family Foundation
Available from: 2017-01-02 Created: 2017-01-02 Last updated: 2019-09-06Bibliographically approved
Hamlett, E. D., Goetzl, E. J., Ledreux, A., Vasilevko, V., Boger, H. A., LaRosa, A., . . . Granholm, A.-C. (2017). Neuronal exosomes reveal Alzheimer's disease biomarkers in Down syndrome. Alzheimer's & Dementia, 13(5), 541-549
Open this publication in new window or tab >>Neuronal exosomes reveal Alzheimer's disease biomarkers in Down syndrome
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2017 (English)In: Alzheimer's & Dementia, ISSN 1552-5260, E-ISSN 1552-5279, Vol. 13, no 5, p. 541-549Article in journal (Refereed) Published
Abstract [en]

INTRODUCTION: Individuals with Down syndrome (DS) exhibit Alzheimer's disease (AD) neuropathology and dementia early in life. Blood biomarkers of AD neuropathology would be valuable, as non-AD intellectual disabilities of DS and AD dementia overlap clinically. We hypothesized that elevations of amyloid-β (Aβ) peptides and phosphorylated-tau in neuronal exosomes may document preclinical AD.

METHODS: AD neuropathogenic proteins Aβ1-42, P-T181-tau, and P-S396-tau were quantified by enzyme-linked immunosorbent assays in extracts of neuronal exosomes purified from blood of individuals with DS and age-matched controls.

RESULTS: Neuronal exosome levels of Aβ1-42, P-T181-tau, and P-S396-tau were significantly elevated in individuals with DS compared with age-matched controls at all ages beginning in childhood. No significant gender differences were observed.

DISCUSSION: These early increases in Aβ1-42, P-T181-tau, and P-S396-tau in individuals with DS may provide a basis for early intervention as targeted treatments become available.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Alzheimer's disease, Amyloid-β, Blood biomarkers, Down syndrome, Hyperphosphorylated tau, Intellectual disability, Neuronal exosomes
National Category
Neurosciences
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-61278 (URN)10.1016/j.jalz.2016.08.012 (DOI)000400554400005 ()27755974 (PubMedID)2-s2.0-85007392964 (Scopus ID)
Available from: 2017-03-10 Created: 2017-03-10 Last updated: 2019-08-29Bibliographically approved
Tusch, E. S., Alperin, B. R., Ryan, E., Holcomb, P. J., Mohammed, A. K. H. & Daffner, K. R. (2016). Changes in Neural Activity Underlying Working Memory after Computerized Cognitive Training in Older Adults. Frontiers in Aging Neuroscience, 8, Article ID 255.
Open this publication in new window or tab >>Changes in Neural Activity Underlying Working Memory after Computerized Cognitive Training in Older Adults
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2016 (English)In: Frontiers in Aging Neuroscience, ISSN 1663-4365, E-ISSN 1663-4365, Vol. 8, article id 255Article in journal (Refereed) Published
Abstract [en]

Computerized cognitive training (CCT) may counter the impact of aging on cognition, but both the efficacy and neurocognitive mechanisms underlying CCT remain controversial. In this study, 35 older individuals were randomly assigned to Cogmed adaptive working memory (WM) CCT or an active control CCT, featuring five weeks of five similar to 40 min sessions per week. Before and after the 5-week intervention, event-related potentials were measured while subjects completed a visual n-back task with three levels of demand (0-back, 1-back, 2-back). The anterior P3a served as an index of directing attention and the posterior P3b as an index of categorizationNVM updating. We hypothesized that adaptive CCT would be associated with decreased P3 amplitude at low WM demand and increased P3 amplitude at high WM demand. The adaptive CCT group exhibited a training-related increase in the amplitude of the anterior P3a and posterior P3b in response to target stimuli across n-back tasks, while subjects in the active control CCT group demonstrated a post-training decrease in the anterior P3a. Performance did not differ between groups or sessions. Larger overall P3 amplitudes were strongly associated with better task performance. Increased post-CCT P3 amplitude correlated with improved task performance; this relationship was especially robust at high task load. Our findings suggest that adaptive WM training was associated with increased orienting of attention, as indexed by the P3a, and the enhancement of categorization/WM updating processes, as indexed by the P3b. Increased P3 amplitude was linked to improved performance; however. there was no direct association between adaptive training and improved performance.

Keywords
computerized cognitive training, working memory, ERPs (Event-Related Potentials), cognitive aging, P3a, P3b, n-back task, P3
National Category
Geriatrics Neurosciences
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-59007 (URN)10.3389/fnagi.2016.00255 (DOI)000387185700001 ()2-s2.0-85006312746 (Scopus ID)
Available from: 2016-12-15 Created: 2016-12-14 Last updated: 2018-11-01Bibliographically approved
Lindau, M., Almkvist, O. & Mohammed, A. K. H. (2016). Effects of Stress on Learning and Memory. In: Stress: Concepts, Cognition, Emotion, and Behavior (pp. 153-160). Academic Press
Open this publication in new window or tab >>Effects of Stress on Learning and Memory
2016 (English)In: Stress: Concepts, Cognition, Emotion, and Behavior, Academic Press, 2016, p. 153-160Chapter in book (Other academic)
Abstract [en]

Stress activates the hypothalamus-pituitary-adrenal axis, which causes the release of glucocorticoids, a class of adrenal steroid hormones. Stress also activates the sympathetic nervous system and thereby, the release of the transmitters adrenaline and noradrenaline. Stress has a memory-modulatory effect in humans as well as in animals. In humans, the hippocampus, prefrontal cortex, and amygdala are rich in cortisol receptors. Acute and tolerable stress may increase memory performance, while excessive levels and chronic stress may have negative effects, thereby mimicking the pattern in animals. Stress in humans seems to have different effects on the various stages of memory (the memory process: encoding, consolidation, and retrieval) and can be enhanced by emotional arousal. Animals learn to associate events in their environment. Studies of the effects of manipulation of corticosterone levels in animals have helped to disentangle the influences of stress on memory and learning, and indicated that low levels enhance spatial learning, whereas higher levels impair performance. © 2016 Elsevier Inc. All rights reserved.

Place, publisher, year, edition, pages
Academic Press, 2016
Series
Handbook of Stress Series ; 1
Keywords
Amygdala, Animals, Emotional arousal, Hippocampus, Humans, Hypothalamus-pituitary-adrenal (HPA) axis, Learning, Memory stage, Memory system, Stress
National Category
Psychology
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-64663 (URN)10.1016/B978-0-12-800951-2.00018-2 (DOI)2-s2.0-85018682819 (Scopus ID)9780128009512 (ISBN)
Available from: 2017-06-02 Created: 2017-06-02 Last updated: 2017-07-25Bibliographically approved
Porto, F. H., Fox, A. M., Tusch, E. S., Sorond, F., Mohammed, A. K. H. & Daffner, K. R. (2015). In vivo evidence for neuroplasticity in older adults. Brain Research Bulletin, 114, 56-61
Open this publication in new window or tab >>In vivo evidence for neuroplasticity in older adults
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2015 (English)In: Brain Research Bulletin, ISSN 0361-9230, E-ISSN 1873-2747, Vol. 114, p. 56-61Article in journal (Refereed) Published
Abstract [en]

Neuroplasticity can be conceptualized as an intrinsic property of the brain that enables modification of function and structure in response to environmental demands. Neuroplastic strengthening of synapses is believed to serve as a critical mechanism underlying learning, memory, and other cognitive functions. Ex vivo work investigating neuroplasticity has been done on hippocampal slices using high frequency stimulation. However, in vivo neuroplasticity in humans has been difficult to demonstrate. Recently, a long-term potentiation-like phenomenon, a form of neuroplastic change, was identified in young adults by differences in visual evoked potentials (VEPs) that were measured before and after tetanic visual stimulation (TVS). The current study investigated whether neuroplastic changes in the visual pathway can persist in older adults. Seventeen healthy subjects, 65 years and older, were recruited from the community. Subjects had a mean age of 77.4 years, mean education of 17 years, mean MMSE of 29.1, and demonstrated normal performance on neuropsychological tests. 1 Hz checkerboard stimulation, presented randomly to the right or left visual hemi-field, was followed by 2 mm of 9 Hz stimulation (TVS) to one hemi-field. After 2 mm of rest, 1 Hz stimulation was repeated. Temporospatial principal component analysis was used to identify the Nib component of the VEPs, at lateral occipital locations, in response to 1 Hz stimulation pre- and post-TVS. Results showed that the amplitude of factors representing the early and late Nib component was substantially larger after tetanic stimulation. These findings indicate that high frequency visual stimulation can enhance the Nib in cognitively high functioning old adults, suggesting that neuroplastic changes in visual pathways can continue into late life. Future studies are needed to determine the extent to which this marker of neuroplasticity is sustained over a longer period of time, and is influenced by age, cognitive status, and neurodegenerative disease. (C) 2015 Elsevier Inc. All rights reserved.

Keywords
Neuroplasticity, Visual evoked potentials (VEPs), Normal cognitive aging, Tetanic visual
National Category
Neurology
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-46288 (URN)10.1016/j.brainresbull.2015.03.004 (DOI)000355365600007 ()25857946 (PubMedID)2-s2.0-84927927822 (Scopus ID)
Available from: 2015-09-14 Created: 2015-09-14 Last updated: 2017-12-04Bibliographically approved
Codita, A., Mohammed, A. K. H., Willuweit, A., Reichelt, A., Alleva, E., Branchi, I., . . . Krackow, S. (2012). Effects of spatial and cognitive enrichment on activity pattern and learning performance in three strains of mice in the IntelliMaze.. Behavior Genetics, 42(3), 449-460
Open this publication in new window or tab >>Effects of spatial and cognitive enrichment on activity pattern and learning performance in three strains of mice in the IntelliMaze.
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2012 (English)In: Behavior Genetics, ISSN 0001-8244, E-ISSN 1573-3297, Vol. 42, no 3, p. 449-460Article in journal (Refereed) Published
Abstract [en]

The IntelliMaze allows automated behavioral analysis of group housed laboratory mice while individually assigned protocols can be applied concomitantly for different operant conditioning components. Here we evaluate the effect of additional component availability (enrichment) on behavioral and cognitive performance of mice in the IntelliCage, by focusing on aspects that had previously been found to consistently differ between three strains, in four European laboratories. Enrichment decreased the activity level in the IntelliCages and enhanced spatial learning performance. However, it did not alter strain differences, except for activity during the initial experimental phase. Our results from non-enriched IntelliCages proved consistent between laboratories, but overall laboratory-consistency for data collected using different IntelliCage set-ups, did not hold for activity levels during the initial adaptation phase. Our results suggest that the multiple conditioning in spatially and cognitively enriched environments are feasible without affecting external validity for a specific task, provided animals have adapted to such an IntelliMaze.

National Category
Psychology
Research subject
Social Sciences, Psychology
Identifiers
urn:nbn:se:lnu:diva-61289 (URN)10.1007/s10519-011-9512-z (DOI)000304118300010 ()22187051 (PubMedID)
Available from: 2017-03-10 Created: 2017-03-10 Last updated: 2019-08-30Bibliographically approved
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