This investigation explored implicit and explicit memory consequences of age differences in susceptibility to distraction when previous distraction occurs as target information in a later memory task. Younger and older adults were presented with either implicit (Study 1) or explicit (Studies 2 and 3) memory tasks that included previously distracting and new words. Study 1 explored whether prior exposure to distraction would transfer to improve memory when previously distracting words were included in list to be studied for a recall task. Older adults recalled more previously distracting than new words whereas younger adults recalled the same amount of previously distracting and new words. This initial study was implicit in its use of previously distracting information in that participants were neither informed nor aware of their prior exposure to words in the recall task. Here, only older adults’ memory was influenced by prior exposure to distraction and their recall actually increased to the level of younger adults with implicit use of distraction to improve performance. Subsequent studies investigated explicit influences of prior exposure to distraction on later memory. In Study 2, both younger and older adults showed reliable memory for previously distracting words in an explicit recognition task. These results suggest that although younger adults encode distraction, they do not transfer this information when previous distraction occurs as target stimuli in an implicit memory task. Study 3 investigated whether participants would transfer previous distraction to improve recall if the task was explicit in its use of previous distraction. When cueing instructions were given before the memory task informing participants of the connection between tasks, older adults once again recalled more previously distracting than new words. In contrast to the results of Study 1, younger adults also recalled more previously distracting than new words. Taken together, the results indicate that younger adults do encode distraction, but they require explicit instructions to transfer their knowledge of distraction to later tasks. In contrast, older adults apply their knowledge of distraction in both implicit and explicit memory tasks. Implications are discussed in terms of inhibitory control theory and age differences in strategies engaged in memory tasks.

While the hippocampus may play an essential role in the expression of memories soon after training, over time these memories are thought to become increasingly dependent on coordinated activity in a broad network of cortical and subcortical brain regions. However, the distributed nature of this representation has made it challenging to define the neural elements of the memory trace, and lesion and electrophysiological approaches provide only a narrow window into what is appreciated to be a much more global network. Here global mapping approaches are used to identify networks of brain regions that are activated and co-activated following recall of recent and remote contextual fear memory in mice. Analysis of Fos expression across 84 brain regions allowed for the description of brain-wide activity and interactivity of brain regions associated with memory expression. Activity analysis revealed that remote memory engages a broad collection of cortical and subcortical regions in comparison to recent memory expression. Interactivity analyses revealed that functional connectivity associated with fear memories depends on memory age and is altered in mutant mice that exhibit premature forgetting. In-depth functional connectivity analysis of remote long-term fear memory indicates that memory recall engages a network that has a distinct thalamic-hippocampal-cortical signature. This network is concurrently integrated and segregated and therefore has small-world properties as well as a resilient core of highly inter-connected regions. Centrality measures identify a collection of regions that may play a critical role in the function of the network including expected regions such as the anterior cingulate cortex and prelimbic cortex as well as novel regions including the reuniens thalamic nucleus. Post conditioning lesions of the reuniens lead to mild deficits in contextual fear memory expression providing support for the idea that identified hub regions may play a critical role in the function of the network. These results identify and describe functional activity and interactivity of brain regions underlying recent and remote fear memory expression and provide strong evidence for reorganization and distribution of the functional organization of memories over time.

The Notch receptor and its ligands constitute a ubiquitous signaling pathway found throughout all multicellular animal life. In addition to its highly conserved function in development, a growing body of evidence suggests Notch signaling has important roles to play in adult processes, including long-term memory (LTM) formation. Building on previous work showing a specific requirement for the Notch1 receptor in spatial memory in mice, I show here a similar requirement for the Notch ligand Jag1. Mice with mutations to Dll1 (another Notch ligand) and Lfng (a Notch regulatory protein) do not display such phenotypes. I propose a model in which signaling between Notch pathway components found in the adult mouse hippocampus (such as Notch1 and Jag1) is required for LTM encoding, with no requirement for pathway components not expressed in this tissue (such as Dll1 and Lfng).

Anatomical connectivity and single neuron coding suggest a dissociation of information representation within the lateral and medial entorhinal cortex, a brain region with widespread connections to cortical areas. We aimed to expand this idea by examining differential contribution of these two sub-regions to the retrieval of non-spatial and spatial memory. Inactivation of lateral, but not medial regions severely impaired the retrieval of recently and remotely acquired non-spatial memory while spatial memory remained intact. To link functioning of the lateral entorhinal cortex with the known roles of the hippocampus and medial prefrontal cortex for memory retrieval, communication with these two regions was detected as synchronized oscillations in local field potentials. We found that stronger communication between the lateral entorhinal and prefrontal cortex during stimulus-free periods correlated with better memory performance. The lateral entorhinal cortex therefore may serve as a gateway of memory-related information between the medial prefrontal and other cortical regions.

Visual short-term memory (VSTM) is a vital cognitive ability, allowing us to hold online the contents of visual awareness. Healthy older adults have reduced VSTM capacity compared to young adults; however recent evidence suggests that their performance may be improved by the use of a retroactive cue (“retro-cue”). The retro-cue reduces interference from irrelevant items within VSTM. Mild cognitive impairment (MCI) patients have reduced VSTM performance, compared to healthy older adults. Here, we examined whether the use of a retro-cue would increase VSTM capacity in MCI patients. By presenting a retro-cue after a to-be remembered array, we direct attention to the to-be probed location, which reduces interference from other items that are no longer relevant. The present findings suggest that VSTM capacity per se is not compromised in MCI patients, but these patients may be more susceptible to the effects of interference.

Anatomical connectivity and single neuron coding suggest a dissociation of information representation within the lateral and medial entorhinal cortex, a brain region with widespread connections to cortical areas. We aimed to expand this idea by examining differential contribution of these two sub-regions to the retrieval of non-spatial and spatial memory. Inactivation of lateral, but not medial regions severely impaired the retrieval of recently and remotely acquired non-spatial memory while spatial memory remained intact. To link functioning of the lateral entorhinal cortex with the known roles of the hippocampus and medial prefrontal cortex for memory retrieval, communication with these two regions was detected as synchronized oscillations in local field potentials. We found that stronger communication between the lateral entorhinal and prefrontal cortex during stimulus-free periods correlated with better memory performance. The lateral entorhinal cortex therefore may serve as a gateway of memory-related information between the medial prefrontal and other cortical regions.

Visual short-term memory (VSTM) is a vital cognitive ability, allowing us to hold online the contents of visual awareness. Healthy older adults have reduced VSTM capacity compared to young adults; however recent evidence suggests that their performance may be improved by the use of a retroactive cue (“retro-cue”). The retro-cue reduces interference from irrelevant items within VSTM. Mild cognitive impairment (MCI) patients have reduced VSTM performance, compared to healthy older adults. Here, we examined whether the use of a retro-cue would increase VSTM capacity in MCI patients. By presenting a retro-cue after a to-be remembered array, we direct attention to the to-be probed location, which reduces interference from other items that are no longer relevant. The present findings suggest that VSTM capacity per se is not compromised in MCI patients, but these patients may be more susceptible to the effects of interference.

Although forgetfulness is a common and naturally occurring phenomenon, research suggests that it can be intentionally induced using several experimental paradigms. For some individuals, the ability to forget negative thoughts, images, or memories is problematic. That is, the inability to forget may be a source of significant psychological distress (e.g., post-traumatic stress, obsessive-compulsiveness, and depressed mood) that contributes to the maintenance of symptoms of various mental health disorders. The schema-activation hypothesis from Becks (1987) Cognitive Theory of Depression suggest that memories should be more readily brought to mind because they are more readily available through associated activation. Thus, negative memories may be difficult to inhibit (forget), for individuals who are depressed compared to non-depressed counterparts. <p> Indeed, suppression effort (the intentional mental effort to not think about something) often leads to an increase in the very cognitive content targeted for forgetting. For individuals who experience depression or dysphoria, suppression is not effective because the negative cognitive content, which is the hallmark the depressed mood state only serves to maintain or exacerbate the mood state. This raises the question of whether there are alternatives to suppression-like paradigms that may be more efficacious for those who are dysphoric or depressed. Investigating the efficacy of induced-forgetting of negative memories may provide researchers and clinicians with additional avenues to explore the therapeutic potential of induced forgetting as an intervention or preventive strategy in combating depressed mood states. <p>The purpose of the present study was threefold: first, this study examined whether individual differences (e.g., mood state) in a persons ability to call to mind (remember) negative self-relevant memories would affect memory generation time. Second, the implications of differences in mood for the efficacy of two experimental forgetting paradigms Directed Forgetting (DF) and Retrieval Induced Forgetting (RIF) were explored. Finally, individual differences in mental control (i.e., perceived mental controllability, mental control strategies, and rumination as a coping response) were examined in terms of their ability to predict who would be better at remembering and forgetting. <p>University students (N = 103) with high and low levels of symptoms of dysphoria were asked to generate a set of 32 negative memories using cue words. After rating their memories for clarity and negative valance, each set of memories was subject to either a Directed Forgetting or Retrieval-Induced Forgetting procedure. Participants also completed self-report measures of mental control and rumination. Individuals who were dysphoric were similar to those who were non-dysphoric in the amount of time it took to generate a set of 32 negative memories. These results failed to support the tenets of the Schema Activation Hypothesis of Becks (1967) Cognitive Theory of Depression. Subsequent analysis revealed that the act of generating negative memories was mood-inducing, which may have negated the effect of mood on generation time. In terms of the effect of mood on induced-forgetting paradigm efficacy, the analysis yielded several null findings. The insufficient power prohibited the ability to detect small effects. <p>Dysphoric individuals evidenced deficits in forgetting for the directed-forgetting but not the retrieval-induced forgetting paradigm, but only when separate analysis of individual paradigms was undertaken. In this case, the effect of mood on forgetting approached significance for the directed-forgetting paradigm but not the retrieval-induced forgetting paradigm. This suggests that inducing forgetting for those who are dysphoric is more likely to be successful if there is no instruction to forget. Finally, it was predicted that poor perceived mental control, a tendency to ruminate, and the use of mental control strategies would correlate with induced-forgetting. Results suggest that individuals who perceive themselves as poor at controlling mental content, and ruminate about their internal experience of sadness are impaired on recall of negative autobiographic memories when asked to forget them. In contrast, mental control variables were not related to the degree of forgetting using retrieval-practice methodology. The results of this study have implications for future research designed to further explore the therapeutic value of induced-forgetting, particularly for the RIF paradigm. That is, the presence of a retrieval-induced forgetting effect for those who are dysphoric could prove to be a beneficial coping strategy to combat unwanted negative memories. It may be important to study the longitudinal value, as well as explore the potential benefits for other psychologically distressing phenomena in which negative memories are a part (e.g., post-traumatic stress). That cognitive factors, such as mental control and ruminative coping, do not share a relationship with degree of forgetting in the RIF paradigm also bodes well in demonstrating a possible therapeutic advantage for RIF compared to DF. Researchers are advised to consider mood and mental control variables in terms of their potential effects on forgetting paradigm efficacy when selecting their methodology in studies of intentional forgetting. This is particularly important when using a university sample of participants. It is often the case with experimental research, that a university sample is used. Given the higher rates of dysphoria and self-reported depressive symptoms that tend to typify university students and therefore, may be higher than in community-based samples, researchers are cautioned to consider the implications of dysphoria on research outcomes when testing induced-forgetting paradigms.

Nowadays, most aspects of our daily lives have been changed by digital technology. Digital content as a new medium has been used widely as memorial to bring back memories of a person, an event or old times. Since all the data probably will exist longer than our lifetime, how should we deal with them and treat them as a heritage? In this project, I am exploring the possibilities of an innovative service that would engage people to preserve memories in the digital age by sharing their stories with future generations. I aim at result that not only allows people to collect stories, but also brings new perspective on how people view their present lives in the community. Moreover, I hope this design will not be limited to Norsjö municipality, but could also bring an extra value to other small communities with similar needs.

The purpose of this thesis was to examine the contribution of episodic memory processes supported by the medial temporal lobes (MTL) to two goal-oriented non-episodic tasks, problem solving and semantic retrieval (verbal fluency). The reported experiments provide evidence for the hypothesis that MTL-based episodic processes are robustly involved in completing non-episodic tasks that are open-ended in that no algorithm or procedure can be applied to obtain task-relevant information. In Experiments 1 and 2, participants were administered the Means-End-Problem-Solving (MEPS) task, an open-ended test of social problem solving. People with impaired episodic memory associated with MTL damage or deterioration, patients with temporal lobe epilepsy or excisions (TLE) and older adults, performed worse than matched controls at solving such problems. Importantly, the participants’ performance on the MEPS as judged by the number of relevant solution steps generated correlated with the number of internal (episodically-relevant) but not external (semantically-relevant) details provided in the solutions. Thus, information derived from episodic memory benefited performance on the MEPS. Experiments 3 and 4 were conducted to ascertain whether open-endedness and episodic relevance are determinants of MTL contributions to performance on tests of verbal fluency, which traditionally are considered the domain of semantic memory. Using fMRI, Experiment 3 tracked the time course of MTL activation as participants performed a fluency task for categories that ranged in episodic relevance. The MTLs were more active throughout for categories that depended on autobiographical memories, not active for categories that were not episodically relevant, and active for episodic/spatial categories only later in the time course as the task moved from being well-defined to open-ended. The necessary involvement of the MTL in these tasks was confirmed by the pattern of spared and impaired performance of patients with TLE on category fluency tasks (Experiment 4). Together, these findings are consistent with the view that MTL-based processes are involved in tasks beyond those that test episodic memory. Furthermore, these studies suggest that performance on non-episodic tasks recruits the MTL most robustly when a task is open-ended.