Repetition and the passage of time influence the consolidation of long-term episodic memories. The experiments presented here have explored the influence of repetition on recent and remote autobiographical memories both behaviorally with regard to qualitative and quantitative measures of content, and neuroanatomically, focusing on changes within the hippocampus and adjacent structures. The first experiment tested the prediction made by MTT that hippocampal memory traces expand and strengthen as a function of repeated memory retrievals. An fMRI paradigm was used to compare the effect of memory retrieval versus the mere passage of time on hippocampal activation. Participants retrieved remote autobiographical memories that had been previously retrieved either one month earlier, two days earlier, or multiple times during the preceding month. Behavioral analyses revealed that the number and consistency of memory details retrieved increased with multiple retrievals but not with the passage of time. Hippocampal activation did not change as a function of either multiple retrievals or the passage of time. The second behavioral investigation was a follow-up to the first experiment, examining the retrieval of those same memories one year later in order to determine whether the level of detail remained stable or whether the memories returned to their original state. Participants reported even more details than they had recalled at least one year earlier, including new details. This finding was consistent across both multiple and single retrieval conditions. These findings together with those of the first study suggest that both repetition and the passage of time are important factors that may result in an increase in recall. The third and final experiment explored the behavioral and neural influences of repeated reactivation of both recent and remote autobiographical memories. Participants were interviewed a total of five times throughout one month and retrieved 20 significant life event memories, from either within the past several months or more than five years ago. Additionally, two fMRI scan sessions were collected, which enabled a direct comparison of the same 20 memories before and after a series of repetitions. Activation increased with repetition in several brain regions including bilateral posterior cingulate and precuneus. Behaviorally, repetition resulted in increased accessibility as suggested by decreased reaction times between the initial and final retrieval sessions, and a general maintenance of the level of recall resulted with repetition.

The aim of the present doctoral thesis was to investigate the ability of patients with Alzheimer's disease (AD) to utilize cognitive support in order to improve episodic remembering. A review of previous research indicated that most studies have failed to find beneficial effects of encoding support on memory in AD patients. The ability to utilize cognitive support (i.e., motoric activities, semantic organization, and semantic knowledge) for episodic remembering was investigated in five studies (Bäckman &amp; Herlitz, 1990; Herlitz, Adolfsson, Bäckman, &amp; Nilsson, in press; Herlitz &amp; Bäckman, 1990; Herlitz &amp; Viitanen, in press; Karlsson et al., 1989). Patients with mild, moderate, or severe AD, and normal older adults participated in the studies. On the basis of the results from these studies and the review of the literature, it was concluded that (a) AD patients, irrespective of dementia severity, perform at a lower level than normal older adults in episodic memory tasks; (b) provided that support is supplied at retrieval, AD patients may be sensitive to manipulations at encoding; (c) the strength of the encoding manipulation determines the size of the memory improvement in AD patients; and (d) depending on dementia severity, the type of encoding support also determines the magnitude of memory improvement obtained. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1991, härtill 5 uppsatser.</p> / digitalisering@umu

In the field of imaging genetics, brain function and structure are used as intermediate phenotypes between genes and cognition/diseases to validate and extend findings from behavioral genetics. In this thesis, three of the strongest candidate genes for episodic memory, KIBRA, BDNF, and APOE, were examined in relation to memory performance and hippocampal/parahippocampal fMRI blood-oxygen level-dependent (BOLD) signal. A common T allele in the KIBRA gene was previously associated with superior memory, and increased hippocampal activation was observed in noncarriers of the T allele which was interpreted as reflecting compensatory recruitment. The results from the first study revealed that both memory performance and hippocampal activation at retrieval was higher in T allele carriers (study I). The BDNF 66Met and APOE ε4 alleles have previously been associated with poorer memory performance, but their relation to brain activation has been inconsistent with reports of both increased and decreased regional brain activation relative to noncarriers. Here, decreased hippocampal/parahippocampal activation was observed in carriers of BDNF 66Met (study II) as well as APOE ε4 (study III) during memory encoding. In addition, there was an additive gene-gene effect of APOE and BDNF on hippocampal and parahippocampal activation (study III). Collectively, the results from these studies on KIBRA, BDNF, and APOE converge on higher medial temporal lobe activation for carriers of a high-memory associated allele, relative to carriers of a low-memory associated allele. In addition, the observed additive effect of APOE and BDNF demonstrate that a larger amount of variance in BOLD signal change can be explained by considering the combined effect of more than one genetic polymorphism. These imaging genetics findings support and extend previous knowledge from behavioral genetics on the role of these memory-related genes.

Learning occurs not only when we encode information but also when we test our memory for this information at a later time. In three empirical studies, I investigated the individual and combined effects of interleaved testing (via repeated rounds of study and test practice) and encoding (via motor enactment) during learning on later cued-recall performance for action phrases. Such materials (e.g., “water the flowers”) contain a verb and a noun and approximate everyday memory that typically revolves around past and future actions. Study I demonstrated that both interleaved testing (vs. study only) and enactment (vs. verbal encoding) individually reduced the forgetting rate over a period of 1 week, but these effects were nonadditive. That is, the direct testing effect on the forgetting rate occurred for verbal, but not for enactive encoding; enactment reduced the forgetting rate for the study-only condition, but not for the study–test condition. A possible explanation of these findings is that both study techniques sufficiently elicit verb–noun relational processing that cannot be increased further by combining them. In Studies II and III, I replicated these testing-effect results and investigated whether they varied as a function of recall type (i.e., noun-cued recall of verbs and verb-cued recall of nouns). For verbal encoding (Study II), the direct testing effect was of similar size for both noun- and verb-cued recall. For enactive encoding, the direct testing effect was lacking irrespective of recall type. In addition, interleaved tests enhanced subsequent re-encoding of action phrases, leading to an accelerated learning. This indirect testing effect was increased for the noun-cued recall of verbs—for both verbal and enactive encoding. A possible explanation is that because nouns are semantically more stable, in that the meaning of nouns changes less over time and across different contexts, they are more recognizable. Hence, associated information (e.g., about the recall status) may be more available to the learner during restudy that, in turn, can initiate more effective re-encoding. The two different testing benefits (i.e., direct and indirect) may, partly, engage different mechanisms, as they were influenced differentially by the manipulations of encoding type and recall type. The findings presented in the thesis provide new knowledge regarding the combined effects of strategies and materials that influence memory. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1. Epub ahead of print. Paper 2: Manuscript. Paper 3: Manuscript.</p>

The Menderes Massif forms a large metamorphic culmination in western Turkey &amp / #8211 / an extensional province where continental lithosphere has been stretching following Palaeogene crustal thickening. Northern sector of the Massif on the horst between G&ouml / rdes and Demirci Basins was chosen for structural analysis aimed to study the tectono-metamorphic evolution of the northern Menderes Massif. Within the study area, four groups of rocks are recognized: (1) the metamorphic rocks &amp / #8211 / orthogneisses and metasediments / (2) pegmatoids / (3) Neogene sedimentary rocks / and (4) Quaternary alluvial sediments. The tectono-metamorphic history of the region involves a regional metamorphism (M1) at upper-amphibolite-facies conditions, coeval with a top-tothe-NNE contractional D1 deformation during the northward backthrusting of Lycian Nappes (Eocene main Menderes metamorphism). Partial anatexis during the latest stages of the M1 was speculated to be the main mechanism for the formation of the migmatites and the granitic magma. Pegmatoid domes and dikes/sills formed during late increments of this phase. A second metamorphism (M2) and coeval top-to-the-NNE deformation (D2) took place during the Early Miocene exhumation of the metamorphic rocks along a presently low-angle normal fault in an extensional shear zone at presumably greenschist facies conditions during declining P-T conditions. The latest deformation phase (D3) is high-angle normal faulting due to N&amp / #8211 / S extension affecting western Anatolia. The E&amp / #8211 / W grabens dissecting the Massif into northern, central and southern submassifs are the result of this phase, commenced during Pliocene-Pleistocene and gave the western Anatolia much of its present-day shape. The evidence presented supports the idea of episodic two-stage extension in western Turkey.

The current study investigated whether there were age-related differences in episodic feeling-of-knowing (FOK) accuracy and whether accuracy was influenced by when the FOK judgments were made. Younger and older participants were randomly assigned to 1 of 4 conditions that manipulated the timing of the FOK in relation to cued-recall and recognition. Age-related differences in FOK accuracy were not reliable either when the FOK was immediate or when it was delayed. Moreover, FOK accuracy was above chance for both age groups. Remember/Know (RK) judgments correlated reliably with FOKs for unrecalled words for both age groups and did not vary by FOK timing. Verbal ability, but not education, health, or perceptual speed, correlated with FOK accuracy. These results suggest that rather than a general age-related deficit in episodic FOK accuracy, the presence of age-related differences in resolution might be influenced by individual differences in such factors as verbal ability and frontal functioning.

In episodic recognition memory, differentiation is the assumption that a study item's pre-existing memory trace is updated when additional study for that item is provided. The differentiation models commonly suppose that episodic memory encoding conforms to this process. Although these models have received considerable support within the literature, results inconsistent with their predictions have also been found. The present paper examined conflicting findings that resulted from study list strength manipulations with rhyming word stimuli and semantically related stimuli. As part of the investigation into this discrepancy, 79 university students participated in a computer-based recognition memory task. In this task, word categories of varying length (short vs. long) and word type (rhyming vs. taxonomic) were presented either five times or once within a mixed study list. Following study, an old-new response paradigm was used to examine recognition memory performance. Results from both the rhyming and taxonomic category stimuli were largely consistent with the previous findings in the literature, indicating that word type does appear to influence recognition memory, even within a mixed study list. These findings are interpreted primarily in terms of word type similarity predictions made by one of the differentiation models. Other possible explanations are also discussed.

Episodic memory for olfactory information is still relatively uncharted. The overall purpose of this thesis is to investigate the sensory and cognitive causes of the well-established age-related decline in olfactory episodic odor memory and of the age-independent sex difference in olfactory episodic memory. The purpose of Study I was to investigate the causes of the sex difference in olfactory episodic memory. The results show that the female advantage in episodic recognition memory seems to be explained by women´s higher aptitude in odor identification for familiar odors. With this background, the purpose of Study II was to investigate the age-related decline in olfactory episodic memory, with a particular eye to the role of odor identification. When controlling for the sensory variables olfactory threshold and odor quality discrimination, and the cognitive factor mental speed, the age-related deterioration in odor identification was eliminated. This suggests that changes in basic sensory and cognitive abilities underlie the age-related impairment in odor identification. The purpose of Study III was to investigate the role of recollective experience and intention to memorize for age-related and sex-related differences in episodic odor memory. Younger adults reported more experiences of remembering, and the elderly adults more experiences of feeling of knowing. The participants benefited from intentionality at encoding when the odors were unfamiliar, but intentionality did not affect memory for the familiar odors. The purpose of Study IV was to investigate the role of subjectively perceived qualities of the encoded odors for episodic memory across age and sex. Odors perceived as unpleasant, intense, and irritable were more easily remembered throughout the adult life span. The oldest adults selectively recognized the odors they rated as highly irritable indicating compensatory use of trigeminal activation. Overall, the result suggests that episodic odor memory rely heavily on both sensory and cognitive abilities, but in a different manner depending on demographic factors. The age-related decline appears to be driven by a sensory flattening disabling adequate cognitive processing. The age-independent sex difference on the other hand, is mainly cognitively mediated and driven by cognitive factors such as the ability to verbalize olfactory information.

The aim of this thesis is to examine the underlying cognitive and neural processes at play during retrieval of temporal and contextual source information. This was assessed across three experimental chapters. In the first experimental chapter, Chapter 2, the neural loci of context associations were assessed. Rats trained on an odour-context association task were given lesions to either the Lateral Entorhinal Cortex (LEC) or sham lesions. After surgery, performance on the odour-context task was assessed. It was hypothesised that memory for previously learned odour-context associations would be impaired following LEC lesions but not sham lesions. The results supported this hypothesis, demonstrating impaired memory for the previously learned odour-context associations in the LEC lesion group compared to the Sham lesion. In Chapter 3, the underlying retrieval processes used to retrieve time and context in human memory was assessed across three experiments. It was hypothesised that time would be remembered accurately using both recollection and familiarity, while correct context memory should rely on recollection alone. Two out of the three experiments supported this hypothesis, demonstrating that temporal information can be retrieved using familiarity in certain instances. The final experimental Chapter 4 used fMRI to extend Chapter 3 and examine whether neural activity would be greater in regions associated with recollection during memory for context, while activity in familiarity-related regions would be higher during memory for time. Results revealed no support for these predictions with no regions linked to recollection showing greater context-related activity, and no regions previously linked to familiarity exhibiting increased activation as temporal information was retrieved. The results are discussed in relation to established recollection and familiarity frameworks and previous work examining the neural substrates supporting memory for time and context.

Contexte – Cette recherche analyse les liens entre la pathologie démentielle de type maladie d’Alzheimer (MA) et le Trouble Stress Post Traumatique (TSPT) et vérifie si un traitement du TSPT chez les sujets souffrant de MA peut améliorer l’efficience de la mémoire épisodique, des fonctions cognitives globales et de la qualité de vie des patients. Méthode – Après avoir passé en revue la littérature sur les liens existants entre TSPT et pathologies de type MA, nous proposons l’hypothèse que la détection et le traitement d’un TSPT chez les sujets souffrant de MA pourrait améliorer la mémoire épisodique verbale et la mémoire autobiographique épisodique avec des effets positifs sur l’évolution de la pathologie démentielle. Nous présentons une recherche longitudinale, analysant les données recueillies auprès de 20 sujets cibles (TSPT et MA) et de 20 sujets témoins (MA sans TSPT). Durant trois sessions successives (T0, T1 et T2) séparées par des intervalles de six mois, les différentes composantes de la mémoire épisodique ont été suivies à l’aide de tests spécifiques. L’évolution d’une MA a été vérifiée avec le Mini-Mental State Examination (MMSE). Pour le groupe cible, la présence du TSPT et la qualité de vie ont été testées et un traitement du TSPT a eu lieu entre T0 et T1.Résultats – La littérature scientifique souligne des similitudes entre le TSPT et la MA, avec un rôle clé de la mémoire épisodique. Nos résultats confirment que le traitement d’un TSPT chez les sujets souffrant de MA améliore significativement tous les indicateurs testés : rappel et reconnaissance de mots, rappel immédiat et différé, rappel d’événements de vie, fonctionnement cognitif global et qualité de vie.Discussion/Conclusion – Des données solides existent en faveur de la proposition d’une détection systématique et d’un traitement du TSPT chez les patients avec MA. Cette recherche suggère une voie prometteuse pour les soins de patients atteints de MA et souffrant d’un traumatisme psychique non résolu. / Purpose – This research aims to analyze the links between Alzheimer’s disease (AD) and Post-Traumatic Stress Disorder (PTSD) and to verify if a PTSD treatment can improve episodic memory, global cognitive functioning and quality of life in AD patients.Methods – We review the literature about the links between PTSD and AD, building on several theoretical models. We propose the hypothesis that the treatment of PTSD in AD can improve verbal episodic memory and autobiographical episodic memory with some positive effects on AD evolution. We present a longitudinal study in order to confirm the likely benefits of such an approach. There were 20 participants in the target group (AD and PTSD) and 20 participants in the control group (AD without PTSD). During three sessions (T0, T1 and T2) separated by an interval of six months, different components of episodic memory were assessed with specific tests. AD evolution was assessed with the Mini-Mental State Examination (MMSE). For the target group, PTSD presence and quality of life were also assessed, and treatment for PTSD was undertaken between T0 and T1 for the target group.Results/Findings – The analysis of scientific literature highlighted some clinical, cognitive and neurobiological similarities between AD and PTSD with a key-role of episodic memory. The results of the research indicate that PTSD treatment in AD participants improves significatively all assessed indicators: word recall, word recognition, immediate recall, delayed recall, personal recent events recall, personal lifetime events recall, global cognitive abilities (MMSE) and quality of life.Discussion/Conclusion – There are strong theoretical and practical reasons to search for an effective intervention for PTSD in AD patients. This study indicate a promising avenue for therapeutic care of AD patients with involved trauma.