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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 41 to 50 of 50 (0.017 seconds)| 41 |
Neurophysiological mechanisms of interval timing dissociate inattentive and combined ADHD subtypesBluschke, Annet, Schuster, Jacqueline, Roessner, Veit, Beste, Christian 09 June 2018 (has links)
It is far from conclusive what distinguishes the inattentive (ADD) and the combined (ADHD-C) subtype of ADHD on the neuronal level. Theoretical considerations suggest that especially interval timing processes may dissociate these subtypes from each other. Combining high-density EEG recordings with source localization analyses, we examine whether there are ADHD-subtype specific modulations of neurophysiological processes subserving interval timing in matched groups of ADD (n = 16), ADHD-C (n = 16) and controls (n = 16). Patients with ADD and ADHD-C show deficits in interval timing, which was correlated with the degree of inattention in ADD patients. Compared to healthy controls, patients with ADHD-C display a somewhat weaker, yet consistent response preparation process (contingent negative variation, CNV). In patients with ADD, the early CNV is interrupted, indicating an oscillatory disruption of the interval timing process. This is associated with activations in the supplemental motor areas and the middle frontal gyrus. Patients with ADD display adequate feedback learning mechanisms (feedback-related negativity, FRN), which is not the case in patients with ADHD-C. The results suggest that altered pacemaker-accumulation processes in medial frontal structures distinguish the ADD from the ADHD-C subtype. Particularly in patients with ADD phasic interruptions of preparatory neurophysiological processes are evident, making this a possible diagnostic feature.
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Task Dissociation in Prospective Memory Performance in Individuals With ADHDAltgassen, Mareike, Kretschmer, Anett, Kliegel, Matthias 10 October 2019 (has links)
Objective: The present study investigated, for the first time, event- and time-based prospective memory (PM) in the same sample of adults with ADHD within one paradigm using parallel task constraints. Method: A total of 25 individuals with ADHD and 25 matched neurotypical controls completed a computerized version of the Dresden Breakfast Task, which required participants to prepare breakfast following a set of rules and time restrictions.
Results: Although groups did not differ in event-based PM, results demonstrated a large-sized impairment in individuals with ADHD in time-based PM.
Conclusion: Findings suggest a task-specific impairment in PM functioning and are discussed in an executive control framework of neurocognitive functioning in ADHD. (J. of Att. Dis. 2014; 18(7) 617-624)
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Das dopaminerge System im Gehirn des Menschen: molekulare Grundlagen, Anatomie, Physiologie und PathologieRillich, Jan 02 February 2023 (has links)
Diese Arbeit ist Teil des Toxnetz-Projekts des Fachbereichs Toxikologie an der Universität Leipzig und behandelt Themen rund um den Botenstoff Dopamin. Es wurden hierfür Texte und Essays zu Funktionen, Mechanismen, Hirnarealen und Krankheitsbildern geschrieben, die den Studierenden der Toxikologie als Lernhilfe und Wissensspeicher dienen sollen. Ausführliche Erläuterungen finden sich zu den vier dopaminergen Projektionsbahnen und ihren Interaktionen mit den Basalganglien, dem präfrontalen Cortex, dem Hippocampus und der Amygdala. Die Rolle von Dopamin bei Motivation, Belohnung, Lernen, Gedächtnisbildung und Aufmerksamkeit wird ebenso beleuchtet, wie die bei der Parkinson Krankheit, Schizophrenie, ADHS und Drogensucht.
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Ereignisbezogene Hirnpotentiale bei statischen und bewegten visuellen Reizen. Ein Vergleich von Jungen mit Aufmerksamkeitsdefizit- Hyperaktivitätsstörung und deren gesunden Altersgenossen. / Stimulus-locked brain potential during static and motional visual impulses. A comparison between boys with attention deficit hyperactivity disorder and their healthy age cohortOltmann, Frauke Alexandra 18 June 2012 (has links)
No description available.
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Neural mechanisms underlying successful and deficient multi-component behavior in early adolescent ADHDBluschke, Annet, Gohil, Krutika, Petzold, Maxi, Roessner, Veit, Beste, Christian 11 June 2018 (has links) (PDF)
Attention Deficit Hyperactivity Disorder (ADHD) is a disorder affecting cognitive control. These functions are important to achieve goals when different actions need to be executed in close succession. This type of multi-component behavior, which often further requires the processing of information from different modalities, is important for everyday activities. Yet, possible changes in neurophysiological mechanisms have not been investigated in adolescent ADHD. We examined N = 31 adolescent ADHD patients and N = 35 healthy controls (HC) in two Stop-Change experiments using either uni-modal or bi-modal stimuli to trigger stop and change processes. These stimuli were either presented together (SCD0) or in close succession of 300 milliseconds (SCD300). Using event-related potentials (ERP), EEG data decomposition and source localization we analyzed neural processes and functional neuroanatomical correlates of multicomponent behavior. Compared to HCs, ADHD patients had longer reaction times and higher error rates when Stop and Change stimuli were presented in close succession (SCD300), but not when presented together (SCD0). This effect was evident in the uni-modal and bi-modal experiment and is reflected by neurophysiological processes reflecting response selection mechanisms in the inferior parietal cortex (BA40). These processes were only detectable after accounting for intra-individual variability in neurophysiological data; i.e. there were no effects in standard ERPs. Multi-component behavior is not always deficient in ADHD. Rather, modulations in multi-component behavior depend on a critical temporal integration window during response selection which is associated with functioning of the inferior parietal cortex. This window is smaller than in HCs and independent of the complexity of sensory input.
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Effects of multisensory stimuli on inhibitory control in adolescent ADHD: It is the content of information that mattersChmielewski, Witold X., Tiedt, Angela, Bluschke, Annet, Dippel, Gabriel, Roessner, Veit, Beste, Christian 12 June 2018 (has links) (PDF)
Even though deficits in inhibitory control and conflict monitoring are well-known in ADHD, factors that further modulate these functions remain to be elucidated. One factor that may be of considerable importance is how inhibitory control is modulated by multisensory information processing. We examined the influence of concurrent auditory conflicting or redundant information on visually triggered response inhibition processes in adolescent ADHD patients and healthy controls. We combined high-density event-related potential (ERP) recordings with source localization to delineate the functional neuroanatomical basis of the involved neurophysiological processes. In comparison to controls, response inhibition (RI) processes in ADHD were compromised in conflicting conditions, but showed no differences to controls when redundant or no concurrent auditory information was presented. These effects were reflected by modulations at the response selection stage (P3 ERP) in the medial frontal gyrus (BA32), but not at the attentional selection (P1, N1 ERPs) or resource allocation level (P2 ERP). Conflicting information during RI exerts its influences in adolescent ADHD via response selection mechanisms, but not via attentional selection. It is not the mere presence of concurrent information, but the presence of conflicting information during RI that may destabilize goal shielding processes in medial frontal cortical regions, by means of increasing the automaticity of response tendencies. The occurring RI deficits might relate to the increased impulsivity in adolescent ADHD and a corresponding vulnerability to react to an increased automaticity of pre-potent response tendencies. ADHD patients show a bias to a specific content of information which can modulate inhibitory control.
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Neural mechanisms underlying successful and deficient multi-component behavior in early adolescent ADHDBluschke, Annet, Gohil, Krutika, Petzold, Maxi, Roessner, Veit, Beste, Christian 11 June 2018 (has links)
Attention Deficit Hyperactivity Disorder (ADHD) is a disorder affecting cognitive control. These functions are important to achieve goals when different actions need to be executed in close succession. This type of multi-component behavior, which often further requires the processing of information from different modalities, is important for everyday activities. Yet, possible changes in neurophysiological mechanisms have not been investigated in adolescent ADHD. We examined N = 31 adolescent ADHD patients and N = 35 healthy controls (HC) in two Stop-Change experiments using either uni-modal or bi-modal stimuli to trigger stop and change processes. These stimuli were either presented together (SCD0) or in close succession of 300 milliseconds (SCD300). Using event-related potentials (ERP), EEG data decomposition and source localization we analyzed neural processes and functional neuroanatomical correlates of multicomponent behavior. Compared to HCs, ADHD patients had longer reaction times and higher error rates when Stop and Change stimuli were presented in close succession (SCD300), but not when presented together (SCD0). This effect was evident in the uni-modal and bi-modal experiment and is reflected by neurophysiological processes reflecting response selection mechanisms in the inferior parietal cortex (BA40). These processes were only detectable after accounting for intra-individual variability in neurophysiological data; i.e. there were no effects in standard ERPs. Multi-component behavior is not always deficient in ADHD. Rather, modulations in multi-component behavior depend on a critical temporal integration window during response selection which is associated with functioning of the inferior parietal cortex. This window is smaller than in HCs and independent of the complexity of sensory input.
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Effects of multisensory stimuli on inhibitory control in adolescent ADHD: It is the content of information that mattersChmielewski, Witold X., Tiedt, Angela, Bluschke, Annet, Dippel, Gabriel, Roessner, Veit, Beste, Christian 12 June 2018 (has links)
Even though deficits in inhibitory control and conflict monitoring are well-known in ADHD, factors that further modulate these functions remain to be elucidated. One factor that may be of considerable importance is how inhibitory control is modulated by multisensory information processing. We examined the influence of concurrent auditory conflicting or redundant information on visually triggered response inhibition processes in adolescent ADHD patients and healthy controls. We combined high-density event-related potential (ERP) recordings with source localization to delineate the functional neuroanatomical basis of the involved neurophysiological processes. In comparison to controls, response inhibition (RI) processes in ADHD were compromised in conflicting conditions, but showed no differences to controls when redundant or no concurrent auditory information was presented. These effects were reflected by modulations at the response selection stage (P3 ERP) in the medial frontal gyrus (BA32), but not at the attentional selection (P1, N1 ERPs) or resource allocation level (P2 ERP). Conflicting information during RI exerts its influences in adolescent ADHD via response selection mechanisms, but not via attentional selection. It is not the mere presence of concurrent information, but the presence of conflicting information during RI that may destabilize goal shielding processes in medial frontal cortical regions, by means of increasing the automaticity of response tendencies. The occurring RI deficits might relate to the increased impulsivity in adolescent ADHD and a corresponding vulnerability to react to an increased automaticity of pre-potent response tendencies. ADHD patients show a bias to a specific content of information which can modulate inhibitory control.
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Intact Context-Dependent Modulation of Conflict Monitoring in Childhood ADHDBluschke, Annet, Chmielewski, Witold X., Roessner, Veit, Beste, Christian 18 May 2022 (has links)
Objective: Conflict monitoring is well known to be modulated by context. This is known as the Gratton effect, meaning that the degree of interference is smaller when a stimulus–response conflict had been encountered previously. It is unclear to what extent these processes are changed in ADHD.
Method: Children with ADHD (combined subtype) and healthy controls performed a modified version of the sequence flanker task.
Results: Patients with ADHD made significantly more errors than healthy controls, indicating general performance deficits. However, there were no differences regarding reaction times, indicating an intact Gratton effect in ADHD. These results were supported by Bayesian statistics.
Conclusion: The results suggest that the ability to take contextual information into account during conflict monitoring is preserved in patients with ADHD despite this disorder being associated with changes in executive control functions overall. These findings are discussed in light of different theoretical accounts on contextual modulations of conflict monitoring. (J. of Att. Dis. 2020; 24(11) 1503-1510)
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Fehlerbezogene Hirnpotenziale bei Kindern mit Aufmerksamkeitsdefizit-Hyperaktivitätsstörung (ADHS) / Response-locked brain potentials on children with attention deficit/hyperactivity disorder (ADHD)Kühnert, Ulrike 28 June 2011 (has links)
No description available.
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