This thesis aims to explore the two dominant functional roles of the hippocampal formation, in the relational encoding of episodic memory and the neural representation of allocentric space, using a combination of pharmaceutical manipulations and single-unit recording techniques in rodents. The first part of this thesis focuses on episodic-like memory, defined by the original episodic memory triad: ‘what-where-when’ (Tulving 1972), which enables the behavioural aspects of episodic memory to be tested in non-human animals. Permanent neurotoxic lesions of the hippocampus and it’s subregions were induced to assess their role in a putative episodic-like memory task developed by Eacott and Norman (2004). In view of the difficulties encountered in successfully demonstrating the temporal component of episodic-like memory in rats, this task tested integrated memory for ‘what-where-which’, where the temporal component (when) was replaced with another event specifier: context (on ‘which’ occasion). Disruption of the hippocampal circuitry led to a specific impairment in the integration of all three event components, whereas the associative recognition of any combination of these features in isolation was left intact. These results confirm the hippocampal dependence of this episodic-like memory task and further reveals the necessity of both CA3 and CA1, hypothetically due to the underlying autoassociative role of CA3 with CA1 functioning as the vital output pathway for this associated information and/or as a mismatch detector. There has been much debate over the inclusion of the temporal component and sceptics may argue that any such interpretations of task-dependence on episodic-like memory processing are invalid considering the requirement for temporal processing is absent. Due to the proposal that a temporal framework necessarily provides the foundation on which episodic memories are built, the second chapter focuses on the development of a suitable protocol in which integrated memory for the original ‘what-where-when’ episodic memory triad can be reliably tested. The other main function attributed to the hippocampus was brought to light by the fascinating revelation that it’s neurons selectively fire in different regions of an environment, termed ‘place cells’ (O’Keefe and Dostrovsky 1971). From the numerous publications resulting from this discovery it has emerged that place cells not only respond to the spatial features of the environment but are also sensitive to a multitude of non-spatial features. These characteristics support the logical assumption that the primary firing patterns of the hippocampus should underlie it’s main purported roles, leading to speculations that they reflect episodic memory processes. The second part of this thesis aims to examine the relationship between hippocampal cells and behaviour by extending the work of Ainge et al. (2007a), in which a subset of hippocampal place cells were found to encode both current and intended destination in a double Y-maze ‘win-stay’ task. The development of these ‘goal-sensitive’ cells were initially investigated during the learning phase of this task. An exciting pattern of results showed a strong positive correlation between the emergence of goal-sensitive firing and behavioural performance on the task, tempting speculations that these firing patterns may underlie spatial learning and future planning, necessary to support performance. To ensure these firing patterns were not a mere reflection of greater experience on the maze, a second study was conducted in which the task demands changed over set periods of days. A significant increase in the proportion of cells demonstrating goal-sensitive firing was revealed when the protocol shifted to incorporate the spatial memory demands of the ‘win-stay’ task, with all other parameters of the protocol remaining constant. These results support the theory that goal-sensitive firing patterns are specifically related to the learning and memory demands of the spatial task, not a result of increased exploration of the maze. The last of this series of studies assessed hippocampal-dependence of this task and revealed that bilateral hippocampal lesions induced an impairment in spatial ‘win-stay’ performance. Collectively, these experiments demonstrate that goal-sensitive firing of hippocampal cells emerge in line with behavioural performance in a hippocampal-dependent task and the emergence of these firing patterns are specific to the learning and memory demands of a spatial ‘win-stay’ protocol. The functional role of the hippocampus in allocentric spatial processing may thus underpin it’s function in episodic memory and potentially in the imagining and planning of future events, whereby the hippocampus provides a ‘space’ in which retrieved information can be integrated in a coherent context to support the fluent and flexible use of information. This hippocampal function would necessarily require visual information to be accessed, concerning the arrangement of landmarks and cues within the environment, in association with information regarding internal orientation and direction and this leads to the question assessed in the final part of this thesis of where this integration occurs. Based on anatomical evidence and the current literature, the postsubiculum, an input structure to the hippocampus, emerged as a potential site for the convergence of sensory cues into the internally generated head direction cell and place cell networks to enable hippocampal-dependent spatial processing. Thus, the effects of temporary pharmacological blockade of AMPARs and NMDARs in the postsubiculum were assessed on the encoding of spatial memory in an object recognition paradigm. The impairment revealed in the ability to recognise novel object-place configurations demonstrates a key role for NMDAR-dependent plasticity within the postsubiculum itself in the formation of allocentric spatial memory. In summary, the experimental results reported in this thesis further elucidate the critical role the hippocampal formation plays in spatial and episodic memory by combining evidence from cellular physiology and neuroanatomy to the behaving animal and extends these findings to discuss a more general role for the hippocampus in imagining both past and future events, in order to successfully navigate, learn and enable past experience to influence our intended future plans and decisions.

<p>Nothing has been that consistent as the change is for the knowledge revolution to nourish and cultivate. Different forms of changes are occurring in organizations with the aim to improve the output performances. Health organizations have been more attached to the changes and the consequences that are brought with such changes. Such consequences are primarily connected with concepts of unlearning and learning. Any form of the change if initiated in organization asks for new routines learning, tasks conductions and the organizational cultural revolution. These new routines have been occurring at individual and organizational levels. The unlearning at any level in the organizational culture can be performed through investigating a primary connection between the organizational and individual routines. At the individual level unlearning brings a number of psychological, cognitive, social and moral hurdles. These hurdles at individual level basically help the organizational unlearning to occur. All of the routines occurring at individual level encompass the necessary information that goes from lower levels to upward, strengthening and holding the organizational memory firm.</p><p>This research was about to find how the health organizations unlearn the older practices and learn the new practices in IT change. This research had two streams i) finding whether there had been any connection between the organizational and individual unlearning in the cases of IT change, ii) For unlearning what kind of hurdles had been there at the individual level. Kalmar hospital pediatric department had been chosen for the empirical investigations. The research streams were about how and what parts which helped the researcher to go for the qualitative data gathering techniques.</p><p>The Results showed there had been a very thin connectivity between the organizational and individual unlearning. The results revealed and unfolded that many of the new learning are occurring simultaneously with discarding the older ways of practices. The impression of absorbing the change with respect to the unlearning had been varied from person to person. There had been a numbers of individual hurdles observed at individual level of unlearning. Apart from them, many individual routines (performative tasks) had the primary connectivity with the organizational routines (Ostensive routines) and shaping and reshaping of the organizational memory.</p><p>It is important to understand the unlearning notions with the type of change. In this research each of the interviewee had shared his thoughts of how the things could have been done differently by revealing the consequences with new learning. Literature suggests that for a profound and successful implementation of change more formal and informal trainings, clear strategy for shuffling the older individuals in the camp, more social and cognitive meetings and fast and quick actions in the cases of technical difficulties are to be taken.</p><p><strong> </strong></p><p><strong> </strong></p><p><strong> </strong></p><h1> </h1><h1> </h1><h1> </h1><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p> / Thesis

<p>Nothing has been that consistent as the change is for the knowledge revolution to nourish and cultivate. Different forms of changes are occurring in organizations with the aim to improve the output performances. Health organizations have been more attached to the changes and the consequences that are brought with such changes. Such consequences are primarily connected with concepts of unlearning and learning. Any form of the change if initiated in organization asks for new routines learning, tasks conductions and the organizational cultural revolution. These new routines have been occurring at individual and organizational levels. The unlearning at any level in the organizational culture can be performed through investigating a primary connection between the organizational and individual routines. At the individual level unlearning brings a number of psychological, cognitive, social and moral hurdles. These hurdles at individual level basically help the organizational unlearning to occur. All of the routines occurring at individual level encompass the necessary information that goes from lower levels to upward, strengthening and holding the organizational memory firm.</p><p>This research was about to find how the health organizations unlearn the older practices and learn the new practices in IT change. This research had two streams i) finding whether there had been any connection between the organizational and individual unlearning in the cases of IT change, ii) For unlearning what kind of hurdles had been there at the individual level. Kalmar hospital pediatric department had been chosen for the empirical investigations. The research streams were about how and what parts which helped the researcher to go for the qualitative data gathering techniques.</p><p>The Results showed there had been a very thin connectivity between the organizational and individual unlearning. The results revealed and unfolded that many of the new learning are occurring simultaneously with discarding the older ways of practices. The impression of absorbing the change with respect to the unlearning had been varied from person to person. There had been a numbers of individual hurdles observed at individual level of unlearning. Apart from them, many individual routines (performative tasks) had the primary connectivity with the organizational routines (Ostensive routines) and shaping and reshaping of the organizational memory.</p><p>It is important to understand the unlearning notions with the type of change. In this research each of the interviewee had shared his thoughts of how the things could have been done differently by revealing the consequences with new learning. Literature suggests that for a profound and successful implementation of change more formal and informal trainings, clear strategy for shuffling the older individuals in the camp, more social and cognitive meetings and fast and quick actions in the cases of technical difficulties are to be taken.</p><p><strong> </strong></p><p><strong> </strong></p><p><strong> </strong></p><p><strong> </strong></p><h1></h1><h1></h1><h1></h1><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p><p> </p> / Thesis

It is well established that older adults show a deficit in episodic memory. The associative deficit hypothesis (ADH) (Naveh-Benjamin, 2000) suggests that an age-related reduced ability to create links between units of information is a major contributor to the episodic deficit. It has been a robust finding that older adults show a disproportionate decline in associative memory relative to item memory when compared to young adults. Previous researchers have investigated the role of the frontal lobes (FL) by studying the effect of reduced attentional resources in the associative deficit. However, they have not found that divided attention in young adults produces the disproportionate associative decline seen in aging and it is thought that some cognitive process other than the allocation of attentional resources may contribute to the associative deficit. The present study intended to use a divided attention (DA) task that also engages medial temporal brain regions (MTL) in order to tax additional parts of the network involved in creating associations and provide indirect support for the role of the MTL in the associative deficit. However, the associative memory deficit in older adults was not replicated due to unique poor associative memory performance of some young adults in the study. Analyses excluding these participants show support for the role of the MTL in the associative deficit. However, the young poor performers may provide support for the role of FL function in the associative deficit and show that poor associative memory may not be limited to the older adult cohort.

Evidence suggests that when memories are reactivated they become labile and can be updated or even erased. Reactivation induces plasticity in memory representations, rendering them fragile, much as they were after initial acquisition. When a memory has been reactivated it must be re-stabilized, which requires reconsolidation. A recent set of studies established the phenomenon of memory reconsolidation for episodic memory (Hupbach et al., 2007, 2008, 2011). That reconsolidation effects apply to explicit memory, which requires conscious recollection, has far reaching implications. In the Hupbach et al. studies the ability of subtle reminders to trigger reconsolidation was investigated; these reminders consisted of the same spatial context, the same experimenter and a reminder question. Given we live in a predictable world, episodes are not random occurrences of events in time and space, but instead consist of statistical and semantic regularities. This leaves open the question of whether semantic relations and statistical regularities between episodes can trigger a reactivation of episodic memory. If so, how would this affect the status of the reactivated memory? This dissertation explored the role of semantic relatedness between the elements of different episodes in memory reactivation and subsequent updating. We focused particularly on categorical and contextual aspects of semantic relations. A series of experiments considered different kinds of semantic relations between elements of episodes, providing evidence of memory reactivation and updating as a consequence of basic level category relations between items in two separate episodes. We also tested the predictions of the Temporal Context Model (TCM) (Sederberg et al., 2011) for our experimental paradigm and show that the current TCM model is not able to account for all the effects of semantic relatedness in the reconsolidation paradigm. Finally, we explore an alternative approach that seeks to explain memory reconsolidation as Bayesian Inference. Our results provide support for this Bayesian framework, showing the potential of it for exploring different aspects of memory organization.

Message framing and intergroup contact theories provide the framework for this study to examine how episodic and thematic political message frames affect young adults' attitudes toward older adults and Social Security. Three specific moderators were examined: direct contact, trait empathy, and critical consumption skills. Effects were explored experimentally using manipulated messages about abolishing Social Security. Results indicated that political message framing related to public policies does affect attitudes toward those policies. Respondents in the episodic condition reported significantly more negative attitudes toward Social Security than respondents in the thematic and control conditions. A significant effect on individual attribution of responsibility was also found such that respondents in the thematic condition rated individual responsibility significantly lower than respondents in the atypical condition. The study extends previous work by examining both intended and unintended attitudinal consequences of message frames.

<p>Involuntary episodic memories are memories that come into consciousness without preceding retrieval effort. These memories are commonplace and are relevant to multiple mental disorders. However, they are vastly understudied. We use a novel paradigm to elicit involuntary memories in the laboratory so that we can study their neural basis. In session one, an encoding session, sounds are presented with picture pairs or alone. In session two, in the scanner, sounds-picture pairs and unpaired sounds are reencoded. Immediately following, participants are split into two groups: a voluntary and an involuntary group. Both groups perform a sound localization task in which they hear the sounds and indicate the side from which they are coming. The voluntary group additionally tries to remember the pictures that were paired with the sounds. Looking at neural activity, we find a main effect of condition (paired vs. unpaired sounds) showing similar activity in both groups for voluntary and involuntary memories in regions typically associated with retrieval. There is also a main effect of group (voluntary vs. involuntary) in the dorsolateral prefrontal cortex, a region typically associated with cognitive control. Turning to connectivity similarities and differences between groups again, there is a main effect of condition showing paired > unpaired sounds are associated with a recollection network. In addition, three group differences were found: (1) increased connectivity between the pulvinar nucleus of the thalamus and the recollection network for the voluntary group, (2) a higher association between the voluntary group and a network that includes regions typically found in frontoparietal and cingulo-opercular networks, and (3) shorter path length for about half of the nodes in these networks for the voluntary group. Finally, we use the same paradigm to compare involuntary memories in people with posttraumatic stress disorder (PTSD) to trauma-controls. This study also included the addition of emotional pictures. There were two main findings. (1) A similar pattern of activity was found for paired > unpaired sounds for both groups but this activity was delayed in the PTSD group. (2) A similar pattern of activity was found for high > low emotion stimuli but it occurred early in the PTSD group compared to the control group. Our results suggest that involuntary and voluntary memories share the same neural representation but that voluntary memories are associated with additional cognitive control processes. They also suggest that disorders associated with cognitive deficits, like PTSD, can affect the processing of involuntary memories.</p> / Dissertation

The role of the primate frontopolar cortex (FPC) has been investigated using human neuroimaging, lesion and disruption techniques. The results of these investigations have led to a variety of theories regarding the function of this region. It has been linked to the formation of task sets, the performance of multiple tasks, reasoning, context-specific memory (including episodic memory, prospective memory and source memory), attention to internally or externally generated information, mentalising and decision-making. It has not previously been possible to study this area using animal lesion techniques. Here, behavioural experiments conducted using non-human primates (rhesus macaque monkeys) who have received lesions to the frontal pole investigate the contribution of this region to context-specific memory, decision-making and social cognition. Functional magnetic resonance imaging (fMRI) is used to investigate changes in functional network connectivity which occur after lesions to this region. A long-lasting impairment is observed in contextual memory judgements (specifically, how recently a stimulus was encountered) after lesions to the frontal pole. An analysis of the influence of the outcomes of previous choices on behaviour on an analogue to the Wisconsin Card Sorting Test (WCST) indicate that monkeys with lesions to area 10 may be less influenced by the outcomes of an extended history of rewards than control animals. Long-lasting widespread disruption to functional networks after lesions to this region indicate that indirect anatomical connections from this region to posterior areas play a crucial role in the normal functioning of posterior networks.

The goal of this work is to design a model of episodic memory for virtual agents capable of creating false memories and implement its prototype. The model architecture is inspired by present day knowledge about human episodic memory. Core structures in our model are the chronobags storing details of experienced episodes, and the schemabag storing the general scripts for all experienced events. The episodes are stored in the form of AND-OR trees and it is possible to derive missing details from the stored scripts during recall. We followed the work of Burkert and implemented a prototype of designed memory model in Java using the Pogamut 3 Framework. The model is parameterizable and it is evaluated in several experiments. In these experiments we looked on the trends in correct and incorrect recalls over time and we simulated the experiment demonstrating existence of room schemata. We compared the results produced by our model with the data from psychological researches and we showed that our model can produce false memories similar to false memories recollected by humans.

Previous studies have suggested that short-term and long-term memory processes in- dependently affect performance in the sentence-imitation task. The multi-component working memory model by Baddeley and Hitch offers a suitable theoretical description of how these processes contribute to this performance. In order to examine the influence of language knowledge located in the long-term me- mory on performance in the sentence-imitation task while statistically controlling for the influence of short-term memory, we assigned to our participants different tasks testing their language knowledge, phonological short-term memory (phonological loop), com- plex short-term memory (central executive) and the sentence-repetition task. Results from hierarchical linear regression yield significant contribution of the tasks testing language knowledge to explaining the variance in the sentence-imitation task, while controlling for the contributions from the phonological and complex short-term memory tasks. These results are in accordance with previous research and the theory of multi-component working memory. Keywords: working memory, episodic buffer, sentence imitation