Contemporary theories on frequency processing have been developed in different sub-disciplines of psychology and have shown remarkable discrepancies. Thus, in judgment and decision making, frequency estimates on serially encoded events are mostly traced back to the availability heuristic (Tversky & Kahneman, 1973). Evidence for the use of this heuristic comes from several popular demonstrations of biased frequency estimates. In the area of decision making, these demonstrations led to the conclusion that frequency judgments were generally error-prone. On the other hand, in memory literature detailed computational memory models are used to explain frequency estimates. Although these models to some degree differ evidently in their specific representational assumptions, they all arrive at the basic prediction that frequency estimates should usually be quite accurate but regressed. This prediction was confirmed in numerous studies. However, up to now there have been no systematic efforts in memory literature to identify factors that cause biases in frequency judgments and to explain the demonstrations of erroneous estimates in the area of decision making. The two studies presented in this thesis pursue the questions whether memory models are able to explain errors in frequency judgments and to generate new predictions about biasing factors. In the focus of the first series of experiments is the "famous-names effect": If participants are presented with a list of names of female and male persons, then the frequency of that sex is overestimated that was represented with more famous names on the list. As more famous names are additionally recalled better, this effect was usually explained with the availability heuristic. An alternative account was suggested within the framework of the associationist-model PASS (Sedlmeier, 1999) and the multiple-trace model MINERVA-DM (Dougherty et al., 1999). According to this, the effect is primarily caused by the different pre-experimental frequencies of famous and non-famous names. If this is correct, the famous-names effect should generalize to any stimulus material. This hypothesis was tested in four experiments. The predictions of the memory models were compared with the predictions of a recall-estimate version of the availability heuristic (e.g. Watkins & LeCompte, 1991). Contrary to the predictions of all tested approaches, the participants were mostly able to judge the frequencies of the presented categories approximately correctly. The results indicate furthermore that systematic biases only occurred if the participants based their judgments at least partially on the recall-estimate strategy. However, as the participants only did this in exceptional cases the entire result pattern is explained best within a multiple strategy perspective (Brown, 2002). A re-analysis of the data from all four experiments suggests that the size of the sample of retrieved exemplars is the crucial factor for the (additional) use of the recall-estimate strategy. In the second study new predictions about the influence of associations on frequency estimates are derived from the PASS-model and tested. In two experiments words that were either strongly or weakly associated with each other were presented to the participants. Predictions of the PASS model for the frequency estimates about this stimulus material were gained by means of simulations. In a first step PASS acquired associations between the stimulus words from a large text corpus. Subsequently, the model encoded the experimental study lists. PASS expects higher frequency judgments for associated than for non-associated words. The size of this effect should be independent of the actual presentation frequencies of the words. Finally, the model expects that the frequencies of associated words are discriminated slightly worse than the frequencies of non-associated words. These predictions were largely confirmed in both experiments. The decision times required by the participants to generate their estimates indicate here that they did not base their judgments on the recall-estimate strategy. The results thus strengthen the assumption that the encoding and representation of frequency information are based on associative learning. / Aktuelle Theorien zur Häufigkeitsverarbeitung wurden in unterschiedlichen Teilgebieten der Psychologie entwickelt und weisen erstaunliche Diskrepanzen auf. So werden Häufigkeitsschätzungen über seriell enkodierte Ereignisse in der Urteils- und Entscheidungsforschung zumeist auf die Verfügbarkeitsheuristik (Tversky & Kahneman, 1973) zurückgeführt. Evidenz für die Verwendung dieser Heuristik stammt aus einigen populären Demonstrationen fehlerhafter Häufigkeitsschätzungen. Diese Demonstrationen führten in der Entscheidungsforschung zu der Schlussfolgerung, dass Häufigkeitsurteile generell fehleranfällig seien. Demgegenüber wurden in der Gedächtnispsychologie detaillierte, computerimplementierte Gedächtnismodelle benutzt, um Häufigkeitsschätzungen zu erklären. Obwohl sich diese Modelle in ihren spezifischen Repräsentationsannahmen zum Teil deutlich unterscheiden, kommen sie alle zu der grundlegenden Vorhersage, dass Häufigkeitsschätzungen in der Regel recht genau, aber regrediert sein sollten. Diese Vorhersage wurde in zahlreichen Untersuchungen bestätigt. In der gedächtnispsychologischen Forschung hat es jedoch bisher kein systematisches Bemühen gegeben, Faktoren, die zu Verzerrungen in Häufigkeitsschätzungen führen, zu identifizieren und die Demonstrationen fehlerhafter Schätzungen aus der Entscheidungsforschung zu erklären. Die zwei in der vorliegenden Arbeit präsentierten Studien verfolgen die Fragestellung, inwieweit Gedächtnismodelle in der Lage sind, Fehler in Häufigkeitsurteilen zu erklären und neue Vorhersagen über verzerrende Faktoren zu generieren. Im Mittelpunkt der ersten Serie von Experimenten steht dabei der "Famous-Names Effekt": Nach der Präsentation einer Liste mit Namen weiblicher und männlicher Personen wird die Häufigkeit desjenigen Geschlechts überschätzt, das mit berühmteren Namen auf der Liste vertreten war. Da berühmtere Namen zudem besser erinnert werden, wurde dieser Effekt gewöhnlich auf die Verfügbarkeitsheuristik zurückgeführt. Eine Alternativerklärung wurde sowohl im Rahmen des assoziationistischen PASS-Modells (Sedlmeier, 1999) als auch innerhalb des Exemplarmodells MINERVA-DM (Dougherty et al., 1999) vorgeschlagen. Demnach wird der Effekt primär durch die unterschiedliche prä-experimentelle Häufigkeit berühmter und nicht-berühmter Namen verursacht. Ist diese Annahme korrekt, so sollte der Famous-Names Effekt auch auf anderes Stimulusmaterial generalisieren. Diese Hypothese wurde in vier Experimenten überprüft. Dabei wurden die Vorhersagen der Gedächtnismodelle mit den Vorhersagen einer "Recall-Estimate" Version der Verfügbarkeitsheuristik (z. B. Watkins & LeCompte, 1991) verglichen. Entgegen den Vorhersagen aller getesteten Ansätze waren die Teilnehmer in der Regel in der Lage, die Häufigkeit der verwendeten Kategorien recht gut einzuschätzen. Die Ergebnisse sprechen zudem dafür, dass systematische Fehler in den Häufigkeitsurteilen nur dann auftraten, wenn sich die Teilnehmer bei der Generierung ihrer Schätzungen zumindest teilweise auf die Recall-Estimate Strategie stützten. Da die Teilnehmer dies jedoch nur in Ausnahmefällen taten, kann das gesamte Ergebnismuster am besten innerhalb einer "Multiple Strategy Perspective" (Brown, 2002) erklärt werden. Eine Reanalyse der Daten aus allen vier Experimenten legt dabei die Schlussfolgerung nahe, dass die Stichprobengröße erinnerter Exemplare ausschlaggebend für die (zusätzliche) Verwendung der Recall-Estimate Strategie ist. In der zweiten Studie werden neuartige Vorhersagen über den Einfluss von Assoziationen auf Häufigkeitsschätzungen aus dem PASS-Modell abgeleitet und getestet. In zwei Experimenten wurden den Teilnehmern Wörter präsentiert, die untereinander entweder stark oder schwach assoziiert waren. Die Vorhersagen des PASS-Modells über die Häufigkeitsschätzungen zu diesem Stimulusmaterial wurden mit Hilfe von Simulationen gewonnen. In einem ersten Simulationsschritt erwarb PASS aus großen Textkorpora Assoziationen zwischen den Stimuluswörtern. Anschließend enkodierte das Modell die experimentellen Stimuluslisten. PASS erwartet, dass assoziierte Wörter höhere Schätzungen erhalten als nicht-assoziierte Wörter. Die Größe dieses Effekts sollte von der Präsentationshäufigkeit der Wörter unabhängig sein. Schließlich erwartet das Modell, dass die Häufigkeit assoziierter Wörter geringfügig schlechter diskriminiert wird als die Häufigkeit nicht-assoziierter Wörter. Diese Vorhersagen wurden in beiden Experimenten weitgehend bestätigt. Die Verwendung einer Recall-Estimate Strategie konnte dabei mit Hilfe von Reaktionszeitmessungen ausgeschlossen werden. Die Ergebnisse stützen damit die Annahme, dass die Enkodierung und Repräsentation von Häufigkeitsinformation auf assoziativem Lernen basiert.

Background: Maintaining independence in instrumental activities of daily living (IADL) is crucial for older adults. This study explored the association between cognitive and functional performance in general and in single IADL domains. Also, risk factors for developing IADL impairment were assessed. Methods: Here, 3,215 patients aged 75–98 years were included. Data were collected during home visits. Results: Cognitive functioning was associated with IADL both cross-sectionally and longitudinally. Regarding the single IADL domains cross-sectionally, executive functioning was especially associated with shopping, while episodic memory was associated with responsibility for own medication. Conclusion: Reduced performance in neuropsychological tests is associated with a greater risk of current and subsequent functional impairment. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

In the first part of this thesis, we generalize a coding theorem and a converse of Kadota and Wyner (1972) to abstract channels with time structure. As a main contribution we prove the coding theorem for a significantly weaker condition on the channel output memory, called total ergodicity for block-i.i.d. inputs. We achieve this result mainly by introducing an alternative characterization of information rate capacity. We show that the ψ-mixing condition (asymptotic output-memorylessness), used by Kadota and Wyner, is quite restrictive, in particular for the important class of Gaussian channels. In fact, we prove that for Gaussian channels the ψ-mixing condition is equivalent to finite output memory. Moreover, we derive a weak converse for all stationary channels with time structure. Intersymbol interference as well as input constraints are taken into account in a flexible way. Due to the direct use of outer measures and a derivation of an adequate version of Feinstein’s lemma we are able to avoid the standard extension of the channel input σ-algebra and obtain a more transparent derivation. We aim at a presentation from an operational perspective and consider an abstract framework, which enables us to treat discrete- and continuous-time channels in a unified way. In the second part, we systematically analyze infinite output memory conditions for abstract channels with time structure. We exploit the connections to the rich field of strongly mixing random processes to derive a hierarchy for the nonequivalent infinite channel output memory conditions in terms of a sequence of implications. The ergodic-theoretic memory condition used in the proof of the coding theorem and the ψ-mixing condition employed by Kadota and Wyner (1972) are shown to be part of this taxonomy. In addition, we specify conditions for the channel under which memory properties of a random process are invariant when the process is passed through the channel. In the last part, we investigate cascade and integration channels with regard to mixing conditions as well as properties required in the context of the coding theorem. The results are useful to study many physically relevant channel models and allow a component-based analysis of the overall channel. We consider a number of examples including composed models and deterministic as well as random filter channels. Finally, an application of strong mixing conditions from statistical signal processing involving the Fourier transform of stationary random sequences is discussed and a list of further applications is given. / Im ersten Teil der Arbeit wird ein Kodierungstheorem und ein dazugehöriges Umkehrtheorem von Kadota und Wyner (1972) für abstrakte Kanäle mit Zeitstruktur verallgemeinert. Als wesentlichster Beitrag wird das Kodierungstheorem für eine signifikant schwächere Bedingung an das Kanalausgangsgedächtnis bewiesen, die sogenannte totale Ergodizität für block-i.i.d. Eingaben. Dieses Ergebnis wird hauptsächlich durch eine alternative Charakterisierung der Informationsratenkapazität erreicht. Es wird gezeigt, dass die von Kadota und Wyner verwendete ψ-Mischungsbedingung (asymptotische Gedächtnislosigkeit am Kanalausgang) recht einschränkend ist, insbesondere für die wichtige Klasse der Gaußkanäle. In der Tat, für Gaußkanäle wird bewiesen, dass die ψ-Mischungsbedingung äquivalent zu endlichem Gedächtnis am Kanalausgang ist. Darüber hinaus wird eine schwache Umkehrung für alle stationären Kanäle mit Zeitstruktur bewiesen. Sowohl Intersymbolinterferenz als auch Eingabebeschränkungen werden in allgemeiner und flexibler Form berücksichtigt. Aufgrund der direkten Verwendung von äußeren Maßen und der Herleitung einer angepassten Version von Feinsteins Lemma ist es möglich, auf die Standarderweiterung der σ-Algebra am Kanaleingang zu verzichten, wodurch die Darstellungen transparenter und einfacher werden. Angestrebt wird eine operationelle Perspektive. Die Verwendung eines abstrakten Modells erlaubt dabei die einheitliche Betrachtung von zeitdiskreten und zeitstetigen Kanälen. Für abstrakte Kanäle mit Zeitstruktur werden im zweiten Teil der Arbeit Bedingungen für ein unendliches Gedächtnis am Kanalausgang systematisch analysiert. Unter Ausnutzung der Zusammenhänge zu dem umfassenden Gebiet der stark mischenden zufälligen Prozesse wird eine Hierarchie in Form einer Folge von Implikationen zwischen den verschiedenen Gedächtnisvarianten hergeleitet. Die im Beweis des Kodierungstheorems verwendete ergodentheoretische Gedächtniseigenschaft und die ψ-Mischungsbedingung von Kadota und Wyner (1972) sind dabei Bestandteil der hergeleiteten Systematik. Weiterhin werden Bedingungen für den Kanal spezifiziert, unter denen Eigenschaften von zufälligen Prozessen am Kanaleingang bei einer Transformation durch den Kanal erhalten bleiben. Im letzten Teil der Arbeit werden sowohl Integrationskanäle als auch Hintereinanderschaltungen von Kanälen in Bezug auf Mischungsbedingungen sowie weitere für das Kodierungstheorem relevante Kanaleigenschaften analysiert. Die erzielten Ergebnisse sind nützlich bei der Untersuchung vieler physikalisch relevanter Kanalmodelle und erlauben eine komponentenbasierte Betrachtung zusammengesetzter Kanäle. Es wird eine Reihe von Beispielen untersucht, einschließlich deterministischer Kanäle, zufälliger Filter und daraus zusammengesetzter Modelle. Abschließend werden Anwendungen aus weiteren Gebieten, beispielsweise der statistischen Signalverarbeitung, diskutiert. Insbesondere die Fourier-Transformation stationärer zufälliger Prozesse wird im Zusammenhang mit starken Mischungsbedingungen betrachtet.

Evidence from self-reports and laboratory studies suggests that recall of nontrauma autobiographical memories may be disturbed in posttraumatic stress disorder (PTSD), but investigations in everyday life are sparse. This study investigated unintentional nontrauma and trauma memories in trauma survivors with and without PTSD (N = 52), who kept an autobiographical memory diary for a week. We investigated whether unintentional nontrauma memories show an overgeneral memory bias and further memory abnormalities in people with PTSD, and whether unintentional trauma memories show distinct features. Compared to the no-PTSD group, the PTSD group recorded fewer nontrauma memories, which were more overgeneral, more often from before the trauma or related to the trauma, were perceived as distant, and led to greater dwelling. Trauma memories were more vivid, recurrent, and present and led to greater suppression and dwelling. Within the PTSD group, the same features distinguished trauma and nontrauma memories. Results are discussed regarding theories of autobiographical memory and PTSD.

Background: Maintaining independence in instrumental activities of daily living (IADL) is crucial for older adults. This study explored the association between cognitive and functional performance in general and in single IADL domains. Also, risk factors for developing IADL impairment were assessed. Methods: Here, 3,215 patients aged 75–98 years were included. Data were collected during home visits. Results: Cognitive functioning was associated with IADL both cross-sectionally and longitudinally. Regarding the single IADL domains cross-sectionally, executive functioning was especially associated with shopping, while episodic memory was associated with responsibility for own medication. Conclusion: Reduced performance in neuropsychological tests is associated with a greater risk of current and subsequent functional impairment.

No description available.

BACKGROUND.One group of theories aiming at providing a framework explaining the etiology, maintenance and phenomenology of anxiety disorders is classified as cognitive models of anxiety. These approaches assume that distortions in specific levels of information processing are relevant for the onset and maintenance of the disorder. A detailed knowledge about the nature of these distortions would have important implications for the therapy of anxiety, as the implementation of confrontative or cognitive elements precisely fitting the distortions might enhance efficacy. Still, these models and related empirical evidence provide conflicting assumptions about the nature of disorder-linked processing distortions. Many cognitive models of anxiety (e.g., Fox, Russo, & Dutton, 2002; Mathews & Mackintosh, 1998; Williams, Watts, MacLeod, & Mathews, 1997) postulate that anxiety-linked biases of attention imply hypervigilance to threat and distractibility from other stimuli in the presence of feared materials. This is convincingly confirmed by various experimentalclinical studies assessing attention for threat in anxious participants compared to non-anxious controls (for a review, seeMathews &MacLeod, 2005). In contrast, assumptions concerning anxiety-linked biased memory for threat are less convincing; based on the shared tendency for avoidance of deeper elaboration in anxiety disorders, some models predict memory biases only for implicit memory tasks (Williams et al., 1997) or even disclaim the relevance of memory in anxiety at all (e.g., Mogg, Bradley, Miles, & Dixon, 2004). Other theories restrict the possibility of measuring disorder-specific memory biases to tasks that require merely perceptual encoding of the materials instead of verbal-conceptual memory (e.g., Fox et al., 2002; Mathews &Mackintosh, 1998). On the one hand, none of these models has integrated all the inconsistencies in empirical data on the topic. On the other hand, the numerous empirical studies on memory in anxiety that have been conducted with varying materials, anxiety disorders, encoding and retrieval conditions do not allow final conclusions about the prerequisites for finding memory biases (for a review, see MacLeod & Mathews, 2004). A more detailed investigation of the complete spectrum of memory for threat utilizing carefully controlled variations of depth of encoding and materials is needed. In view of these inconsistencies, it is all the more surprising that one important part of this spectrum has so far remained completely uninvestigated: visual working memory (VWM). No study has ever differentially addressed VWM for threat in anxious vs. nonanxious participants and none of the cognitive models of anxiety provides any predictions concerning this stage of information processing. Research on cognitive biases in anxiety has thus far only addressed the two extremes of the processing continuum: attention and longer-term memory. In between, a gap remains, the bridging of which might bring us closer to defining the prerequisites of memory biases in anxiety. As empirical research has provided substantial and coherent knowledge concerning attention in anxiety, and as attention and VWM are so closely linked (see, for instance, Cowan, 1995), the thorough investigation of VWM may provide important clues for models of anxiety. Is anxiety related to VWM biases favoring the processing of threatening information, or does the avoidance presumed by cognitive models of anxiety already begin at this stage? RESEARCH AIMS. To investigate the relevance of biased VWM in anxiety, the present research focused in eight experiments on the following main research questions: (1) Is threat preferably stored in VWM in anxious individuals? (2) Does threat preference occur at the cost of the storage of other items, or is extra storage capacity provided? (3) Would the appearance of threat interrupt ongoing encoding of non-threatening items? (4) Does prioritized encoding of threat in anxiety occur strategically or automatically? (5) Are disorder-specific VWM biases also materials-specific? (6) Are VWM biases in anxiety modifiable through cognitive-behavioral therapy? METHODS. In Experiments 1-4, a spatial-sequential cueing paradigm was used. A subset of real-object display items was successively cued on each trial by a sudden change of the picture background for 150 ms each. After the cueing, one of the display pictures was hidden and probed for a memory test. On most trials, a cued item was tested, and memory accuracy was determined depending on the item’s position within the cue string and depending on its valence. In some cases, memory for an uncued item was tested. Experiment 1 and 2 were directed at discovering whether spider fearfuls and non-anxious controls would differ with respect to the accuracy in memorizing cued spiders and uncued spiders and, thus, reveal disorder-specific biases of VWM. In addition, the question whether the presence of a spider image is related to costs for the memorization of other images was tested. Experiment 3 addressed whether any disorder-specific VWM biases found earlier were specific to the feared spiders. Therefore, the critical stimuli here were a snake and a spider. Participants were spider fearfuls and non-anxious controls, both without snake anxiety. In Experiment 4, it was tested whether disorder-specific biases found in Experiment 1 and 2 were modifiable through cognitive-behavioral treatment. The critical stimulus was a spider image. Spider fearfuls were tested three times. Half of them received a cognitive-behavioral intervention after the first test, the other half only after the second test. In two additional experiments, VWM was assessed with a change-detection paradigm. The main aim was to clarify whether disorder-specific effects found in the previous experiments were associated with automatic or with strategic selective encoding of threatening materials, and whether any group differences in spider change detection were materials-specific to spiders, but not to snakes. In Experiment 5, several images were presented simultaneously in a study display for either 100 or 500 milliseconds. After a short interruption, a test display was presented including either the same items as the first one or one changed item. Participants’ accuracy in determining whether displays were the same or different was measured depending on the valence of the changed item, set size, and presentation time of the display. There were trials with and without spiders. If a change was made, it could involve either a non-spider or a spider item. Of specific interest was the condition in which a spider image was presented initially, but not in the test phase, as noticing this specific change would require storage of that image in VWM. Would group differences be particularly pronounced in the shorter encoding condition suggesting automatic encoding of threat, or would they occur in the longer encoding condition, suggesting strategic encoding of spiders? In Experiment 6, change detection accuracy for spiders vs. snakes was tested. The participants in both experiments were spider fearfuls vs. controls, but those of Experiment 6 were additionally required to lack snake anxiety. Moreover, a temporal VWM paradigm - an attentional blink task - was applied to assess whether a biased encoding of spider images in spider fearfuls would occur at the expense of non-threatening items undergoing concurrent processing, and whether this effect was specific to spiders, but not to snakes. Series of real-object pictures were presented at rates of 80 ms at the display center. The observer’s task was to identify and report the two target pictures indicated by a brighter background. In Experiment 7, the first target always depicted a neutral item. The valence of the second target was varied - either negative depicting a spider, positive, or neutral. Participants varied with respect to their spider anxiety. In Experiment 8, spider fearfuls and non-anxious controls, both without snake anxiety, were tested. The experiment was nearly the same as the previous one, but two negative target types were tested: disorder-relevant spiders and negative but not feared snakes. Of specific interest was whether the appearance of a threatening target would reduce the report probability of the earlier attended target, indicating the interruption of its VWM encoding in favor of the threat item. RESULTS. (1) Both anxious and non-anxious controls, showed VWM advantages for negative materials such as spider or snake images. (2) In addition, there were disorderspecific VWM biases: some effects were larger in spider fearfuls than in non-anxious controls and some effects occurred exclusively in spider fearfuls. (3) Group differences and, thus, disorder-specificity were particularly pronounced under competitive circumstances, that is, under the condition of numerous stimuli competing for processing resources: when only little orientation time was allowed, when only little time was provided for selecting and encoding items from a crowd, and when VWMfor the critical item required reflexive instead of voluntary attention. (4) Pronounced memory for task-relevant, voluntarily attended spiders was related to difficulties in disengaging attention from these items in the fearful group, reflected in reduced memory accuracy for the item following it. (5) Disorder-specific VWM biases seem to be based on attentional biases to threatening materials resulting in a very quick, automatic memory consolidation. However, this preferential encoding was not at the cost of neutral materials currently undergoing encoding processes. (6) All disorder-specific VWM biases occured only with fear-related materials, not with other negative materials. (7) Automatic and highly disorder-specific fear-related VWM biases – but not strategic VWM biases occuring in both groups - were modifiable through cognitive-behavioral intervention. CONCLUSIONS. This work provides additional information about informationprocessing distortions related to specific anxiety. With the experimental investigation of biased VWM, this work has been performed to fill a gap within research on cognitive biases in anxiety. Moreover, this dissertation contributes to cognitive theories of anxiety by proposing several recommendations for refinements of current theoretical approaches. Most important, it was suggested to extend existing models by a more detailed consideration of attention and memory. In view of numerous previous empirical studies on the topic and the conclusions of this dissertation, a differentiation of the attentional engagement and disengagement component appears inevitable. Even more important, in view of the data presented here predictions concerning VWM for threatening materials need to be taken into account. In addition, suggestions are provided for the differential consideration of biases occuring from prepotent threat value of negative stimuli vs. individual threat value. A proposal for a cognitive model of anxiety extended by all these aspects is provided to serve as an invitation of further research in the investigation of the nature of memory biases in anxiety disorders. REFERENCES: Cowan, N. (1995). Attention and Memory. An integrated framework.New York: Oxford University Press. Fox, E., Russo, R., & Dutton, K. (2002). Attentional bias for threat: Evidence for delayed disengagement from emotional faces. Cognition and Emotion, 16, 355-379. MacLeod, C., & Mathews, A. (2004). Selective memory effects in anxiety disorders: An overview of research findings and their implications. In D. Reisberg & P. Hertel (eds.), Memory and Emotion. Oxford: Oxford University Press. Mathews, A., & Mackintosh, B. (1998). A cognitive model of selective processing in anxiety. Cognitive Therapy and Research, 22 (6), 539-560. Mathews, A., & MacLeod, C. (2005). Cognitive vulnerability to emotional disorders. Annual Review of Clinical Psychology, 1, 167-195.Mathews, Mogg, May, & Eysenck (1989). Mogg, K., Bradley, B.P., Miles, F., & Dixon, R. (2004). Time course of attentional bias for threat scenes: Testing the vigilance avoidance hypothesis. Cognition and Emotion, 18(5), 689-700. Williams, J.M.G., Watts, F.N., MacLeod, C., & Mathews, A. (1997). Cognitive psychology and emotional disorders. Chichester: John Wiley.

Recent research, that has been focused on recognition memory, has revealed that two processes contribute to recognition of previously encountered items: recollection and familiarity (Aggleton & Brown, 1999; Eichenbaum, 2006; Eichenbaum, Yonelinas, & Ranganath, 2007; Rugg & Yonelinas, 2003; Skinner & Fernandes, 2007; Squire, Stark, & Clark, 2004; Wixted, 2007a; Yonelinas, 2001a; Yonelinas, 2002). The findings of neural correlates of recollection and familiarity lead to the assumption that there are different brain regions activated in either process, but there are, to the best of my knowledge, no studies assessing how these brain regions are working together in a recollection or a familiarity network, respectively. Additionally, there are almost no studies to date, which directly searched for overlapping regions. Therefore, in study I of the current thesis, brain regions associated to both recognition processes are searched investigated. Additionally, a connectivity analysis will search for functional correlated brain activations that either build a recollection or a familiarity network. It is undoubtable that the Brain Derived Neurotrophic Factor (BDNF) is strongly involved in synaptic plasticity in the hippocampus (Bramham & Messaoudi, 2005) and there is evidence that a genetic variant of this neurotrophin (BDNF 66Met) is related to poorer memory performance (Egan, et al., 2003). Therefore, in study II of the current thesis, the effect of BDNF Val66Met on recollection and familiarity performance and related brain activations is investigated. Finally, one could summarize, that serotonin, like BDNF, is strongly involved in brain development and plasticity as well as in learning and memory processes (Vizi, 2008). More precisely, there is evidence for alterations in the structure of brain regions, which are known to be involved in emotional memory formation and retrieval, like amygdala and hippocampus (Frodl, et al., 2008; Munafo, Brown, & Hariri, 2008; Pezawas, et al., 2005). One study found an slight epistatic effect of BDNF and 5-HTTLPR on the grey matter volume of the amygdala (Pezawas, et al., 2008). Therefore, in study III, it is investigated if such an interaction effect could be substantiated for the amygdala and additionally revealed for the hippocampus. The results of the current thesis allow further comprehension of recollection, hence episodic memory, and point to a special role of the BDNF in temporal and prefrontal brain regions. Additionally, the finding of an epistatic effect between BDNF and serotonin transporter function point to the need of analyzing interactions between genes and also between genes and environmental factors which reveals more information than the study of main effects alone. In conclusion, analyzing behavioral and neural correlates of episodic memory reveal allowed insights in brain functions that may serve as guideline for future studies in clinical populations with memory deficits, including susceptibility factors such as good or bad environment, as well as promising gene variants that influence episodic memory.

Der armenisch-türkische Konflikt ist eines der zentralen Themen in der armenischen Wochenzeitung Agos. Die Karikaturisten Aret Gicir, Ohannes Saskal und Sarkis Pacaci bebildern diesen Konflikt in der Sprache der Karikaturen. Die Zeitung ist dabei auch ein Medium für das kollektive Gedächtnis der Armenier in der Türkei und in der Diaspora. Die vorliegende Arbeit untersucht die Rolle der Karikaturen als Erinnerungsfiguren und die Rolle der Karikaturisten als Erinnerungsträger in den armenischen Medien, hier namentlich die Wochenzeitung Agos, für den kollektiven Konstruktionsprozess. Ohne Medien sind keine Erinnerungen möglich und Karikaturen sind ein Medium der Erinnerung. Die Karikaturisten Aret Gicir, Ohannes Saskal und Sarkis Pacaci verwenden unterschiedliche Techniken und Bildersprachen. Ihre Karikaturen gleichen Graffitis, Piktogrammen oder erotischen Darstellungen, sie sind Botschaften und Symbole einer kulturellen Hinterlassenschaft, so wird beispielsweise der tabuisierte Diskurs der Sexualität mit dem tabuisierten Diskurs des armenischen Genozids in der Türkei verbunden, ein Tabu wird durch ein anderes Tabu ersetzt. Die vorliegende Arbeit zeigt, dass die Karikaturisten die Funktion von modernen armenischen Aschugs, den Minnesängern der Gemeinschaft, übernehmen. Anstatt die Erinnerungen wie früher persönlich von Dorf zu Dorf tragen, oder wie im europäischen Mittelalter von Burg zu Burg, übernimmt diese Reise der Erinnerung die Zeitung Agos, um den Rezipienten mit Botschaften aus der Heimat zu versorgen. Durch die Zeitung wird der Rezipient an die (armenische) Vergangenheit erinnert. An diese Erinnerung wird versucht, die kollektive Gedächtnis der Armenier als Ersatz für das fehlende kommunikative Gedächtnis zu etablieren. / The Armenian-Turkish conflict is among the key subjects treated in the Armenian weekly Agos. The caricaturists Aret Gicir, Ohannes Saskal, and Sarkis Pacaci illustrate this conflict in the language of caricatures. The newspaper is thus also a medium for the collective memory of Armenians in Turkey and in the diaspora. This dissertation examines the role of caricatures as memory figures and the role of the caricaturists as carriers of memory in the Armenian media, here specifically the Agos weekly, for the collective process of construction. Memories are not possible without media, and caricatures are a medium of memory. The caricaturists Aret Gicir, Ohannes Saskal, and Sarkis Pacaci use different techniques and imagery. Similar to graffiti, pictograms, or erotic depictions, their caricatures are messages and symbols of a cultural legacy. The tabooed discourse on sexuality, for example, is related to the tabooed discourse of the Armenian genocide in Turkey; one taboo replaces another. This thesis shows that the caricaturists assume the function of modern Armenian ashughs, the bards of the community. Instead of the earlier practice of transmitting the memories personally from village to village, or from castle to castle, as was done in medieval Europe, this journey of remembrance is carried out by the Agos newspaper in order to provide recipients with messages from home. The newspaper serves to remind recipients of the (Armenian) past. Through this memory, an attempt is made to establish the collective memory of the Armenians as a substitute for the lacking communicative memory.

Das deklarative Gedächtnis beruht auf Wechselwirkungen zwischen dem medialen Temporallappens (MTL) und Neokortex. Aufgrund der verteilten Natur neokortikaler Netzwerke bleiben zelluläre Ziele und Mechanismen der Gedächtnisbildung im Neokortex jedoch schwer fassbar. Im sechsschichtigen Säugetier-Neokortex konvergieren die Top-Down-Inputs auf Schicht 1 (L1). Wir untersuchten, wie Top-Down-Inputs von MTL die neokortikale Aktivität während der Gedächtnisbildung modulieren. Wir haben zunächst ein Kortex- und Hippocampus-abhängiges Lernparadigma angepasst, in dem Tiere gelernt haben, direkte kortikale Mikrostimulation und Belohnung zu assoziieren. Neuronen in den tiefen Schichten des perirhinalen Kortex lieferten monosynaptische Eingaben in L1 des primären somatosensorischen Kortex (S1), wo die Mikrostimulation vorgestellt wurde. Die chemogenetische Unterdrückung der perirhinalen Inputs in L1 von S1 störte die Gedächtnisbildung, hatte jedoch keinen Einfluss auf die Leistung der Tiere nach abgeschlossenem Lernen. Dem Lernen folgte das Auftreten einer klaren Subpopulation von Pyramidenneuronen der Schicht 5 (L5), die durch hochfrequentes Burst-Feuern gekennzeichnet war und durch Blockieren der perirhinalen Inputs zu L1 reduziert werden konnte. Interessanterweise zeigte ein ähnlicher Anteil an apikalen Dendriten von L5-Pyramidenneuronen ebenfalls eine signifikant erhöhte Ca2+-Aktivität während des Gedächtnisabrufs bei Expertentieren. Wichtig ist, dass die Störung der dendritischen Ca2+-Aktivität das Lernen beeinträchtigte, was darauf hindeutet, dass apikale Dendriten von L5-Pyramidenneuronen eine entscheidende Rolle bei der Bildung des neokortikalen Gedächtnisses spielen. Wir schließen daraus, dass MTL-Eingaben das Lernen über einen perirhinalen vermittelten Gating-Prozess in L1 steuern, der sich in einer erhöhten dendritischen Ca2+-Aktivität und einem Burst-Firing in pyramidalen L5-Neuronen manifestiert. / Declarative memory relies on interactions between the medial temporal lobe (MTL) and neocortex. However, due the distributed nature of neocortical networks, cellular targets and mechanisms of memory formation in the neocortex remain elusive. In the six-layered mammalian neocortex, top-down inputs converge on its outermost layer, layer 1 (L1). We examined how layer-specific top-down inputs from MTL modulate neocortical activity during memory formation. We first adapted a cortical- and hippocampal-dependent learning paradigm, in which animals learned to associate direct cortical microstimulation and reward, and characterized the learning behavior of rats and mice. We next showed that neurons in the deep layers of the perirhinal cortex not only provide monosynaptic inputs to L1 of the primary somatosensory cortex (S1), where microstimulation was presented, but also actively reflect the behavioral outcome. Chemogenetic suppression of perirhinal inputs to L1 of S1 disrupted early memory formation but did not affect animals’ performance after learning. The learning was followed by an emergence of a distinct subpopulation of layer 5 (L5) pyramidal neurons characterized by high-frequency burst firing, which could be reduced by blocking perirhinal inputs to L1. Interestingly, a similar proportion of apical dendrites (~10%) of L5 pyramidal neurons also displayed significantly enhanced calcium (Ca2+) activity during memory retrieval in expert animals. Importantly, disrupting dendritic Ca2+ activity impaired learning, suggesting that apical dendrites of L5 pyramidal neurons have a critical role in neocortical memory formation. Taken together, these results suggest that MTL inputs control learning via a perirhinal-mediated gating process in L1, manifested by elevated dendritic Ca2+ activity and burst firing in L5 pyramidal neurons. The present study provides insights into cellular mechanisms of learning and memory representations in the neocortex.