111 research outputs found
Interference control in working memory : neurobehavioral properties and age differences
No full textThis doctoral thesis aimed to investigate the basic processes of interference control (IC) in working memory (WM). We sought to unravel some of the underlying mechanisms of IC by examining brain correlates, while also trying to understand the differences that arise with advancing adult age. The major findings from these studies are summarized below.Study I. This study consisted of four separate experiments, with different participants in each. Three different versions of the recent-probes task was used to test the effects of a high- compared to a low-interference context on behavioral and neural measures. A combined analysis of all experiments showed that a high-interference context improved performance, both reaction times and accuracy, on the other trial types within the same task. Neuroimaging results revealed greater engagement of inferior frontal gyrus, striatum, parietal cortex, hippocampus, and midbrain in participants performing the task in the high- than participants in the low-interference context. Study II. This study compared groups of older and younger adults to examine age effects of interference control. A verbal 2-back task including proximal and distant lures revealed that older adults were more affected by interference overall, for both proximal and distant lures. Whereas younger adults overcame and were no longer affected by interference beyond 5-/6-back lures, older adults were still highly affected at the most distant 9-/10-back lures. Study III. This study expands on study II by examining brain activity during successful interference control, using a similar task setup. Proactive interference and brain activity in bilateral inferior frontal gyrus and dorsal anterior cingulate cortex declined with increasing lure distance. This decline in relevant brain regions was coupled with an increase in brain activity in left anterior hippocampus. In addition, each successfully resolved lure trial was divided into two groups, those that influenced performance negatively and those that did not. A whole brain analysis showed greater brain activity in bilateral inferior frontal gyrus, bilateral middle frontal gyrus, and dorsal anterior cingulate gyrus for the lure trials that took longer time to respond to accurately. Study IV. This study used four-year follow-up data from the Betula study to examine whether prefrontal brain volumes can be linked to the ability to control interference. Individuals were separated with respect to their ability to control interference. We observed that participants with superior interference control had larger volume of the ventrolateral area of prefrontal cortex (PFC), regardless of participant demographics. Change in volume over a 4-year period could not be linked to change in interference control.Conclusions. The data in this doctoral thesis contribute with new insight into IC in WM. Data suggests that positive task-scale adjustments, due to conflict, is beyond trial-to-trial adaptation, affecting both behavioral and biological aspects of cognition. Improved performance on non-conflict trials could be explained by an upregulation of resources to cope with the high interference environment. Moreover, a characteristic of the general age-related IC deficit was uniquely demonstrated in older adult’s inability to cope with some of the temporal properties of PI, being negatively affected by the most distant lure trials. Results suggest two distinct means for resolving interference in WM. One involves top-down controlled processes for actively resolving lure items within the focus of attention, and the other involves hippocampus related retrieval of source information from outside the focus of attention. The latter is arguably more difficult for older adults due to the strain on hippocampus, and links well with our own results. Results also suggests two distinct levels of influence by interference in WM, which is either being unaffected by PI or being affected negatively by PI, suggesting an ability that can completely overcome PI. Lastly, these results provide new evidence that a relative IC score can be related to volume of specific and relevant regions within PFC, and that this relationship is not modulated by age. This supports a view that grey matter volume in PFC regions play a specific role in overcoming interference during a WM task.List of scientific papersI. Samrani G, Marklund P, Engström L, Broman D, Persson J. Behavioral facilitation and increased brain responses from a high interference working memory context. Scientific Reports. 2018; 8(1), 15308. https://doi.org/10.1038/s41598-018-33616-3 II. Samrani, G, Bäckman, L, Persson, J. Age-differences in the temporal properties of proactive interference in working memory. Psychology and Aging. 2017; 32(8), 722–731. https://doi.org/10.1037/pag0000204 III. Samrani G, Bäckman L, Persson J. A prefrontal – hippocampal shift underlies the temporal dissipation of proactive interference in working memory. [Manuscript]IV. Samrani G, Bäckman L, Persson J. Interference control in working memory is associated with ventrolateral prefrontal cortex volume. [Manuscript]</p
Pengaruh Model pembelajaran Giving Question and Getting Answer Terhadap Hasil Belajar Tematik Siswa Sekolah Dasar
No full textThe main problem in this research is that learning activities are still focused on the teacher, students lack focus in learning and often complain of being bored in learning, resulting in thematic learning outcome skills. This research aims to determine the effect of the Giving Question and Getting Answer learning model on thematic learning outcomes of class IV students at SDN 144 Sumpang Ale, Sinjai Regency. The type of research used in this research is Pre-Experimental Design and is a quantitative type of research. The sample in this study was 21 students. Data collection techniques were carried out using learning results tests and observation sheets. The data analysis technique in this research is descriptive data analysis technique and T-Test. The research results showed that the thematic learning results before implementing the Giving Question and Getting Answer learning model in the pretest were with an average score of 61.4. Meanwhile, the posttest increased with an average score of 80.5. The results of the t-test analysis regarding the influence of the Giving Question and Getting Answer learning model on student learning outcomes show that the significance value obtained is good, namely the influence of the Giving Question and Getting Answer learning model on thematic learning outcomes (Sig = 0.016) is smaller than the alpha value The set value is 0.05 (0.016 < 0.05). Based on the results obtained, it can be concluded that Ho is rejected and H1 is accepted, which states that there is an influence of the use of the Giving Question and Getting Answer learning model on the thematic learning outcomes of class IV students at SDN 144 Sumpang Ale, Sinjai Regency
Interference control in working memory : neurobehavioral properties and age differences [Elektronisk resurs]
No full textThis doctoral thesis aimed to investigate the basic processes of interference control (IC) in working memory (WM). We sought to unravel some of the underlying mechanisms of IC by examining brain correlates, while also trying to understand the differences that arise with advancing adult age. The major findings from these studies are summarized below. Study I. This study consisted of four separate experiments, with different participants in each. Three different versions of the recent-probes task was used to test the effects of a high- compared to a low-interference context on behavioral and neural measures. A combined analysis of all experiments showed that a high-interference context improved performance, both reaction times and accuracy, on the other trial types within the same task. Neuroimaging results revealed greater engagement of inferior frontal gyrus, striatum, parietal cortex, hippocampus, and midbrain in participants performing the task in the high- than participants in the low-interference context. Study II. This study compared groups of older and younger adults to examine age effects of interference control. A verbal 2-back task including proximal and distant lures revealed that older adults were more affected by interference overall, for both proximal and distant lures. Whereas younger adults overcame and were no longer affected by interference beyond 5-/6-back lures, older adults were still highly affected at the most distant 9-/10-back lures. Study III. This study expands on study II by examining brain activity during successful interference control, using a similar task setup. Proactive interference and brain activity in bilateral inferior frontal gyrus and dorsal anterior cingulate cortex declined with increasing lure distance. This decline in relevant brain regions was coupled with an increase in brain activity in left anterior hippocampus. In addition, each successfully resolved lure trial was divided into two groups, those that influenced performance negatively and those that did not. A whole brain analysis showed greater brain activity in bilateral inferior frontal gyrus, bilateral middle frontal gyrus, and dorsal anterior cingulate gyrus for the lure trials that took longer time to respond to accurately. Study IV. This study used four-year follow-up data from the Betula study to examine whether prefrontal brain volumes can be linked to the ability to control interference. Individuals were separated with respect to their ability to control interference. We observed that participants with superior interference control had larger volume of the ventrolateral area of prefrontal cortex (PFC), regardless of participant demographics. Change in volume over a 4-year period could not be linked to change in interference control. Conclusions. The data in this doctoral thesis contribute with new insight into IC in WM. Data suggests that positive task-scale adjustments, due to conflict, is beyond trial-to-trial adaptation, affecting both behavioral and biological aspects of cognition. Improved performance on non-conflict trials could be explained by an upregulation of resources to cope with the high interference environment. Moreover, a characteristic of the general age-related IC deficit was uniquely demonstrated in older adult’s inability to cope with some of the temporal properties of PI, being negatively affected by the most distant lure trials. Results suggest two distinct means for resolving interference in WM. One involves top-down controlled processes for actively resolving lure items within the focus of attention, and the other involves hippocampus related retrieval of source information from outside the focus of attention. The latter is arguably more difficult for older adults due to the strain on hippocampus, and links well with our own results. Results also suggests two distinct levels of influence by interference in WM, which is either being unaffected by PI or being affected negatively by PI, suggesting an ability that can completely overcome PI. Lastly, these results provide new evidence that a relative IC score can be related to volume of specific and relevant regions within PFC, and that this relationship is not modulated by age. This supports a view that grey matter volume in PFC regions play a specific role in overcoming interference during a WM task
Automatic and effortful control of interference in working memory can be distinguished by unique behavioral and functional brain representations
No full textGoal-irrelevant information in working memory (WM) may enter the focus of attention (FOA) during a task and cause proactive interference (PI). In the current study we used fMRI to test several hypotheses concerning the boundary conditions of PI in WM using a modified verbal 2-back task. Temporal distance between item and lure presentation was manipulated to evaluate potential differences among hypothesized states of FOA, short-term memory and long-term memory. PI was present for the most proximal 3-back lures but dissipated with lure distance along with increased activation in brain regions critical for memory recollection, such as right prefrontal cortex, parietal cortex, and hippocampus. Reduced PI and less IFG activation were also observed after repeated item presentation, supporting the notion that a rehearsed encoding of item-context information reduces the need for interference control. Moreover, a trial-by-trial approach revealed activity in ACC, insula, IFG, and parietal cortex with increasing lure trial interference regardless of distance. The current results are first evidence for an observable transition of cognitive control, to include MTL regions involved in recalling task-relevant information from outside the FOA when resolving PI in WM
Profil Fitokimia Simplisia dan Ekstrak Etanol Daun Kedondong Pagar (Lannea coromandelica (Houtt.) Merr.) sebagai Tanaman Obat
No full textLannea coromandelica (Houtt.) Merr., or known as Kedongdong Pagar in Indonesia, family Anacardiaceae, Kedongdong Pagar leaves that has been proved by some villagers of Samakurok, Tanah Jambo Aye district, Northen Aceh, NAD, who consume boiled water of kedongdong pagar leaves to lower blood glucose levels. This study was to determine the class of chemical compounds contained in simplicia and ethanol extracts of the kedongdong pagar leaves from phytochemical screening results. The results of phytochemical screening showed that chemical compounds contained in simplicia and extracts of kedongdong pagar leaves were flavonoids, saponins, glycosides, tannins and steroids/triterpenoids. Based on the studies that have been carried out, Kedongdong Pagar leaves have great potential to be researched and further developed to become one of the sources of medicinal plants in Indonesia.Lannea coromandelica (Houtt.) Merr., atau dikenal sebagai Kedongdong Pagar di Indonesia, famili Anacardiaceae, Daun Kedongdong Pagar telah dibuktikan oleh warga Desa Samakurok, Kecamatan Tanah Jambo Aye, Aceh Utara, NAD, untuk menurunkan kadar glukosa darah dengan mengkonsumsi air rebusan daun kedongdong pagar. Tujuan penelitian ini untuk mengetahui golongan senyawa kimia yang terkandung dalam simplisia dan ekstrak etanol daun kedongdong pagar dari hasil penapisan fitokimia. Hasil penapisan fitokimia menunjukkan bahwa senyawa kimia yang terkandung dalam simplisia dan ekstrak daun kedongdong pagar adalah flavonoid, saponin, glikosida, tanin dan steroid/triterpenoid. Berdasarkan penelitian yang telah dilakukan, daun kedongdong pagar memiliki potensi yang besar untuk diteliti dan dikembangkan lebih lanjut menjadi salah satu sumber tanaman obat di Indonesia
Age differences in the neural response to emotional distraction during working memory encoding
No full textAge-related declines in attention and working memory (WM) are well documented and may be worsened by the occurrence of distracting information. Emotionally valenced stimuli may have particularly strong distracting effects on cognition. We investigated age-related differences in emotional distraction using task-fMRI. WM performance in older adults was lower for emotional compared with neutral distractors, suggesting a disproportional impairment elicited by emotional task-irrelevant information. Critically, older adults were particularly distracted by task-irrelevant positive information, whereas the opposite pattern was found for younger adults. Age groups differed markedly in the brain response to emotional distractors; younger adults activated posterior cortical regions and the striatum, and older adults activated frontal regions. Also, an age by valence interaction was found for IFG and ACC, suggesting differential modulation of attention to task-relevant emotional information. These results provide new insights into age-related changes in emotional processing and the ability to resolve interference from emotional distraction
Médiations culturelles contemporaines et espaces publics urbains : L'expérience spatiale de l'usager à l’épreuve de projets artistiques et numériques
No full textPublic spaces have always played a fundamental role in structuring interactions withinthe city. They serve as a vehicle for social inclusion and remain essential for theharmonious development of the city and the well-being of its inhabitants. Therefore,this thesis aims to examine the current design of these spaces in terms of theireffectiveness, as the city may be facing an exhaustion of these urban spatial models.This research seeks to explore the role that artistic and digital projects can play in therequalification of these spaces. These projects, which we refer to as mediations, will bestudied for their ability to reconnect residents with their living spaces and to inspire newshared imaginaries. By closely observing the implementation of such projects inMontpellier, supported by a local cultural organization, we have identified distinctmodes of activation and reflection around urban public spaces: reading, inhabiting, andproducing space.L’espace public a toujours joué un rôle fondamental dans l'organisation des interactionsau sein de la ville. Il est un vecteur d'inclusion sociale et demeure essentiel audéveloppement harmonieux de la ville ainsi qu'au bien-être de ses habitants. Ainsi, cettethèse se propose d'interroger l’aménagement actuel de ces espaces en questionnant leurefficacité, dans un contexte où la ville semble confrontée à un épuisement des modèlesde spatialité urbaine. Cette recherche examine le rôle potentiel des projets artistiques etnumériques dans la requalification de ces espaces. Ces projets, que nous considéronscomme des médiations, seront étudiés pour leur capacité à retisser des liens entre leshabitants et leurs lieux de vie, tout en faisant émerger de nouveaux imaginairespartagés. En analysant de près le déploiement de tels projets sur le terrainmontpelliérain, soutenus par une structure culturelle implantée localement, nous avonsidentifié différentes modalités d'activation et de réflexion autour des espaces publicsurbains, à savoir : lire, habiter et produire les espaces publics
Restauration aveugle adaptative pour images monochromes et hyperspectrales
No full textLa restauration d'images représente un défi important lorsque les valeurs des paramètres de régularisation, la PSF et d'autres connaissances a priori ne sont pas disponibles. L'objectif de cette thèse est de développer une méthode de restauration facilement applicable en éliminant la nécessité d'informations préalables et d'un réglage empirique des paramètres. Pour atteindre cet objectif, nous avons développé une méthode adaptative de restauration d'images aveugle qui fonctionne sans nécessiter d'informations a priori. Cette méthode peut être appliquée pour restaurer des images monochromes, multispectrales et hyperspectrales, tout en optimisant les résultats de traitement sans nécessiter de réglage empirique des paramètres de régularisation. La supériorité de notre méthode de restauration aveugle adaptative est démontrée grâce à des évaluations sur diverses bases de données d'images, surpassant onze méthodes non-neuronales et neuronales supervisées/ semi-supervisées de l'état de l'art. En conclusion, la méthode proposée peut être facilement appliquée pour restaurer des images dégradées en raison de sa nature aveugle.Image restoration presents a significant challenge when regularization parameter values, PSF, and other a priori knowledge are not available. The objective of this thesis is to develop an easily applicable restoration method by eliminating the necessity for prior information and empirical parameter tuning. To achieve this objective, we have developed an adaptive blind image restoration method that operates without requiring prior information. This method can be applied to restore monochrome, multispectral, and hyperspectral images, while optimizing restoration results without the need for empirical parameter tuning. The superiority of our proposed adaptive blind restoration method is demonstrated through evaluations on diverse image databases, outperforming eleven existing non-neural network and supervised/semi-supervised neural network methods from the state-of-the-art. In conclusion, the proposed method can be easily applied to restore degraded images due to its blind nature
Investigation of opuntia ficus-indica as a biomonitor species of atmospheric pollution
No full textL'objectif de cette étude est d'étudier le potentiel d'Opuntia ficus-indica (Ofi) en tant que biomoniteur dans un environnement contaminé par des dépôts atmosphériques enrichis en métaux lourds. Trois sites d'étude pollués ont été sélectionnés: industriel, minier et routier. Le phénomène de bioaccumulation a été validé en analysant la concentration en métaux lourds par SAA et ICP-MS dans plusieurs raquettes d'âge différent, dans les fruits et les racines. L'identification de l'origine du Pb a été étudiée à partir de la signature isotopique du Pb (TIMS) dans les raquettes, les racines et les sols, avec une caractérisation microscopique (MEB-EDX) des particules déposées à la surface des raquettes. Le taux de bioaccumulation du Pb suite à une exposition racinaire ou foliaire à des particules de fluorapatite synthétisées et enrichies en Pb à permis de préciser les voies de transfert vers la plante. Ainsi, la distribution particulaire ou dispersée du Pb dans les raquettes contaminées a été identifiée au moyen de cartographies MEB-EDX et µXRF. Les résultats obtenus montrent qu'Ofi est un bioaccumulateur du Pb, Cd et Cr. Les signatures isotopiques dans les raquettes révèlent la nature des diverses sources polluantes tout en donnant une indication sur l'évolution de la pollution atmosphérique au cours du temps. Le taux le plus élevé de Pb a été mesuré dans les raquettes contaminées à leur surface par de la fluorapatite. Les analyses microscopiques ont démontré pour les deux approches suivies l'intégration des particules déposées à la surface des raquettes au niveau de la cuticule, des trichomes et des stomates. Cette obsevation est cohérente avec la cartographie obtenue en µXRF. Notre étude démontre le potentiel de cette plante cosmopolite qu'est Ofi en tant que biomoniteur.This study reports the potential of Opuntia ficus-indica (Ofi) as a biomonitor of atmospheric pollution in three heavily polluted sites, i.e., industrial, mining and road sites. The bioaccumulation phenomenon by Ofi was investigated by studying the heavy metal concentrations in different cladodes of various ages, roots and fruits, using AAS and ICP-MS. To identify the origin of Pb in cladodes, two types of methods were used: TIMS analysis which provided the lead isotopes ratios in cladodes, roots and soil samples, and SEM-EDX analysis at the cladode surface which provided the elemental distribution of Pb and airborne particles and a characterization of their chemical structure at the microscopic scale. A second study was also carried out by testing Pb bioaccumulation after foliar and roots exposure to synthesized fluorapatite particles enriched with Pb. SEM-EDS and µXRF analyses were used to follow the Pb concentration from the contaminated surface to the internal tissues. The results show that Ofi is indeed a bioaccumulator of Pb, Cd and Cr. The Pb isotopic signatures indicate that Ofi is a sensitive species to local aerial pollution and their successive cladodes obviously identify the evolution of air pollution with time. In addition, Ofi cladodes were found more contaminated with lead after direct foliar contamination. SEM-EDS measurements underlined in the two studies the retention of deposited particles on specific zones of the cladode surface (cuticle, trichome and stomata), which were also identified by µXRF cartography. These results represent the first demonstration of the potential of using Ofi, a cosmopolitan plant, as a biomonitor
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