A desnutrição protéica precoce afeta as estruturas envolvidas nos mecanismos de comportamento, aprendizagem e memória. Desta forma, o objetivo deste trabalho foi avaliar o desempenho de ratos desnutridos em diversos procedimentos de memória de reconhecimento de objetos. Ratos Wistar machos (n=132) foram submetidos a dietas isocalóricas contendo 6% (Desnutridos) ou 16% de proteína (Controle) durante os primeiros 49 dias de vida. Foi imposto um período de recuperação nutricional do dia 50 a 70 de vida, quando os testes comportamentais foram iniciados. No Experimento I os animais foram colocados em uma arena com um objeto A. Após 3 ou 24 horas desta exposição, o rato retornou para arena com o objeto A e outro objeto B. O Experimento II foi conduzido com três diferentes procedimentos. No primeiro, o animal foi colocado na arena com três objetos diferentes. Após 24 horas desta exposição, o animal foi novamente colocado na arena com dois objetos já conhecidos pelo animal e um novo objeto. No segundo procedimento, os animais foram colocados na arena com dois objetos localizados nos cantos adjacentes da arena. Após 24 horas o animal retornou para a arena com um objeto na mesma posição e o outro objeto no canto diagonal da arena. No terceiro procedimento o animal foi colocado em um contexto A com dois objetos idênticos. Após cinco minutos, o animal foi colocado em um contexto B com dois objetos idênticos, mas diferentes quando comparados aos objetos apresentados no contexto A. Durante a fase de teste, o animal foi colocado em um dos dois contextos com um objeto do contexto A e outro objeto do contexto B. Foi calculado o Índice de Reconhecimento: IR = (tempo gasto no novo objeto/tempo gasto no objeto já conhecido+tempo gasto no novo objeto) X 100. Os dados foram submetidos ao Teste t Student para amostras independentes (p<0,05). Os resultados mostraram que os animais desnutridos apresentaram menores índices de reconhecimento quando comparados aos animais controle em todos os experimentos, sugerindo que a desnutrição protéica precoce prejudica a memória nos procedimentos de reconhecimento de objetos. / Early Postnatal protein malnutrition affects structures involved in the mechanisms of behavior, learning and memory. Thus, the aim of this work was to evaluate the performance of malnourished rats in several procedures of recognition memory for objects. Male Wistar rats (n=132) were submitted to isocaloric diets containing 6% (Malnourished) or 16% of protein (Control) during the first 49 days of life. A nutritional recovery period was imposed from 50 to 70 days of age, when behavioral tests started. In the Experiment I the animals were put in an open field with an object A. After 3 or 24 hours of this exposition, the rat returned in the open field with the object A and another object B. The Experiment II was conducted with three different procedures. In the first one, the animal was placed in the open field with three different objects. After 24 hours, the animal was replaced in the open field with two objects that were already known by the animal and a new object. In the second procedure the animals were placed in the open field with two objects located in the adjacent corners of the open field. After 24 hours the animal returned to the open field with an object in the same position and the other object in the diagonal corner of the open field. In the third procedure the animal was placed in a context A with two identical objects. After five minutes the animal was placed in a context B with two identical objects, but different when compared to the objects presented in the context A. During the test phase, the animal was placed in one of the two contexts with one object from the context A and another object from the context B. It was calculated the recognition index: RI = (time spent in the new object/time spent in the object already known + time spent in the new object) X 100. The data were submitted to a Student´s t test for independent samples (p<0.05). The results showed that malnourished animals presented lower recognition indexes as compared with control animals in all the experiments, suggesting that early protein malnutrition impairs memory in procedures of object recognition.

This study served to further investigate learning and memory, and to offer a potential tool to support educational interventions. More specifically, this was accomplished by an investigation of the physiologic changes in the brain that occurred while students learned medical anatomy. A group of 29 students taking the Gross Anatomy course at Boston University School of Medicine participated in the study. Testing occurred in two sessions: prior to the course and at the completion of the course. For each session, scalp EEG was recorded while participants were shown 176 anatomical terms (132 relevant to the course and 44 obscure) and asked to respond with "Can Define", "Familiar", or "Don't Know". Behavioral results indicated a positive correlation between participants' course grades and performance on the experimental tasks. EEG results were analyzed for event-related potential (ERP) components related to two memory components: familiarity and recollection. Results had a number of indications. For Don't Know responses, a stronger early frontal, late parietal, and late frontal effect occurred more so for terms of Session 1 compared to Session 2. For an analysis of just Session 2 data, results indicated increased activity of the early frontal, late parietal, and late frontal effects for Can Define responses only. Session 2 Can Define responses elicited a stronger early frontal ERP, occurring between 300 and 500 milliseconds yet, the most post-retrieval processing and monitoring appeared for Can Define terms of Session 2. Ultimately, we focused on investigating two points: 1) the effect of classroom learning on memory, and 2) the examination of ERPs as a tool to guide education interventions. Specifically, ERPs would potentially indicate markers to predict whether students would retain materials long before behavioral measures indicate these results. This has potential to determine whether long-lasting or transient learning will occur; as well as the potential to support early intervention strategies for not just students, but also individuals with learning disabilities or memory impairments.

A sequential dependency occurs when the response on the current trial is correlated with responses made on prior trials. Sequential dependencies have been observed in a variety of both perception and memory tasks. Thus, sequential dependencies provide a platform for relating these two cognitive processes. However, there are many issues associated with measuring sequential dependencies and therefore it is necessary to develop measurement models that directly address them. Here, several measurement models of sequential dependencies for both binary and multi-interval response tasks are described. The efficacy of the models is verified by applying them to simulated data sets with known properties. Lastly, the models are then applied to real-world data sets which test the critical assumption that the underlying processes of sequential dependencies are modulated by attention. The models reveal increased vigilance during testing decreases the degree of sequential dependencies.

Recognition memory - a type of episodic memory in long term memory - is known in the literature to be affected by emotion, aging and the modality of the presented stimuli. The major aim of this study was to investigate whether emotional stimuli enhances recognition memory. Another goal was to observe whether modality and aging effects are present and differentiable in a non-Western subject sample. In literature, emotion studies were based on mainly two dimensions of emotions: valence and arousal. However, the contribution of these two dimensions to the enhancement of recognition memory still needs clarification. The present study investigated specifically the effect of valence on recognition memory. Moreover, the experimental manipulations of this study allowed observing the effect of valence on recognition memory due to normal aging. Since modality of the presented stimuli is a major confounding factor on recognition, separate experiments involving visual and verbal stimuli were designed. Pictures and words were selected on the basis of valence and arousal ratings. The stimulus set of the visual recognition memory task consisted of the pictures selected from the International Affective Picture System (IAPS) (Lang et al., 2005). The stimulus set of the verbal recognition memory task was constructed from partially standardized material for affective norms of Turkish emotional words (METU TEW), which was developed as a part of this study. METU TEW allowed selecting words with positive, neutral and negative valence while controlling arousal. The results replicated two findings reported in the literature: (1) younger adults recognized more accurately than older adults / (2) recognition memory was enhanced for visual items regardless of age and valence. Interestingly, this study revealed that recognition memory was not enhanced for emotional stimuli varying only on the valence dimension. More specifically, there was a decline in recognition memory for positive items and no change was observed for negative items, regardless of age. Further analysis also revealed that there may be differential effects of abstractness and concreteness on verbal recognition memory in aging.

The present study investigated the reliability and robustness of a new mnemonic strategy - self-imagination - in a group of memory-impaired individuals with neurological damage. Despite severe memory deficits, almost all of the participants demonstrated a self-imagination effect (SIE) for recognition memory in study 1. Moreover, the ability to benefit from self-imagination was not affected by the severity of the memory deficit. In study 3, more than half of the participants showed a SIE on a task of event-based prospective memory. The data from study 2 suggest the SIE is not attributable to semantic processing or emotional processing and indicate that self-imagination is distinct from other mnemonic strategies. Overall the findings from the present study implicate self-imagination as a new and effective mnemonic strategy. The data also indicate that when it comes to memory there is something special about processing information in relation to the self.

C-type Natriuretic Peptide (CNP), a relatively new member of the natriuretic peptide family, is found throughout the central nervous system. Circumstantial evidence associates CNP with learning and memory, as its expression is highest in brain regions known to be involved in memory and associated with hippocampal physiology. Here, the first study housed rats in an enriched environment, regarded as providing an 'informal' learning experience, for either 14 or 28 days of housing in enrichment in six regions of interest, which was attributed to changes in the degradation of CNP. The second study examined a group of rats trained on object -recognition task – the bow-tie maze. A difference was found in CNP production in the limbic medial prefrontal cortex over repeated exposures to novel objects relative to controls that received 'yoked learning' an exposure only to the test room. CNP concentrations also tended to be lower in rats with better levels of discrimination between familiar objects. Together, these studies provide some initial evidence that CNP influences learning –induced plasticity in the intact brain.

The present thesis aimed to investigate the source of interference in recognition memory. There are two primary alternatives – the item noise approach, in which interference comes about as a consequence of the other items on the study list, and the context noise approach, wherein interference arises from the previous contexts in which an item has been encountered. Alternatively, interference may occur through a combination of both item and context noise. There are many mathematical models designed to simulate the recognition process that incorporate either item or context noise, or both. Item noise models predict a significant list length effect, that is, that memory for an item that was part of a short list at study is better than that for an item that was part of a long list. Context noise models no not predict a significant difference in memory based on the length of the study list. The presence or absence of the list length effect can therefore be used as a mechanism by which to differentiate item and context noise models. The list length effect is among the most documented and replicated findings in the recognition memory literature (Gronlund & Elam, 1994). Yet, while many experiments have been conducted which have identified a significant list length effect in recognition (e.g. Bowles & Glanzer, 1983; Cary & Reder, 2003; Murnane & Shiffrin, 1991; Ohrt & Gronlund, 1999; Strong, 1912; Underwood, 1978), a number of published studies have failed to identify the effect (e.g. Dennis & Humphreys, 2001; Dennis, Lee & Kinnell, 2008; Jang & Huber, 2008; Murnane & Shiffrin, 1991; Schulman, 1974). Dennis and Humphreys (2001) argued that studies that had identified a significant effect of list length on recognition performance had done so because of a failure to control for four potentially confounding variables; retention interval, attention, displaced rehearsal and contextual reinstatement. The possible confounding effects of retention interval and displaced rehearsal are already well established in the literature and most studies employ some controls for these. Dennis et al. (2008) also found that while the role of contextual reinstatement had a pronounced influence on the detection of the list length effect it did not appear to be the most influential of the potential confounds. Thus, a major aim of the present thesis was to investigate the role of attention in the identification of the list length effect. Experiment 1 (N=160) involved two manipulations of attention. The first was to use either a retroactive or proactive design, with differential lapses of attention likely to be more pronounced in the latter. Second, in one condition participants were asked to perform a pleasantness rating task at study, a common technique to encourage participants to attend to the stimulus, while in the other condition they were asked to simply read the words. Results indicated that attention modulates the list length effect and that it is the retroactive versus proactive distinction which is most important as a significant effect of list length was found only when the proactive design was used. The encoding task had little effect. The design of Experiment 2 (N=80) was based on Cary and Reder's (2003) Experiment 3 which itself was a partial replication of Dennis and Humphreys' (2001) experiments. Cary and Reder introduced the Remember-Know (RK) task into the test list in their experiments and identified a significant effect of list length in the presence of controls for the four confounds where Dennis and Humphreys had not. The RK task is thought to index the relative contributions of familiarity and recollection in the recognition process (Gardiner, 1988). To the extent that the RK task encourages a recall-like process (see Clark, 1999; Diana, Reder, Arndt & Park, 2006) it may influence the results regarding the list length effect, in that the effect is widely accepted to occur in recall. Experiment 2 compared recognition memory with or without RK instructions. One condition involved the standard yes/no recognition paradigm, while the other made us of the RK task following all “yes” responses. Controls for the four potential confounds of Dennis and Humphreys were implemented. No significant effect of list length was identified in the accuracy data of either condition, however there was a small but significant effect on median response latency for correct responses in the RK task condition. The results of Experiments 1 and 2 suggest that the effect of list length on recognition performance is negligible and nonsignificant when controls for the four potential confounds of list length are in place. However, both of these experiments, and almost all previous experiments investigating the list length effect, used words as the stimuli. The remaining four experiments in the present thesis (N=40 in each) sought to investigate the list length effect using stimuli other than words in an attempt to identify the boundary conditions of the effect. Each of these experiments followed the same basic method as Experiments 1 and 2. Four different kinds of stimuli were investigated, word pairs, images of novel faces, fractals and photographs. Results indicated a nonsignificant effect of list length for word pairs and photographs, however, there was a significant list length effect when faces (in the accuracy data) and fractals (in the response latency data) were used as the stimuli. However, all of the experiments in the present thesis used a within subjects manipulation of list length in order to maximise experimental power. This design may be an additional confound of the list length effect. The nature of the within subjects design means that by the end of the second study list, all participants will have studied the same number of items, thereby potentially removing any list length manipulation from the experiment. In addition, participants who studied the long list first may be more likely to be affected by lapses in attention than participants who began with the short list with this, rather than interference, the potential cause of any list length differences. In order to investigate this potential confounding, the results from all experiments of the present thesis were re-analysed using a between subjects analysis based on only the first list studied by each participant. The qualitative conclusions drawn from the majority of conditions remained unchanged. The between subjects analysis generally revealed larger effect sizes than did the within subjects analysis, although with the exception of the proactive conditions, these effects can be considered negligible to small at most. The pattern of results across the six experiments of the present thesis are problematic for existing mathematical models of recognition memory. While context noise models are able to account for negligible and nonsignificant effects of list length when words, word pairs and photographs are used as the stimuli, they are unable to predict a slightly larger and significant list length effect when the stimuli are novel faces or fractals. Conversely, while item noise models are able to account for a significant list length effect for faces and fractals, they are unable to predict a nonsignificant list length effect for words and word pairs. The results question whether either item or context noise can be taken as the sole source of interference in recognition memory. Rather, a combination of interference from different sources may be at work, with the precise nature of this combination dependent on the nature of the stimuli involved. However, it is important to note that these models must be able to all but eliminate interference from other items under certain conditions to obtain the negligible list length effect findings reported here. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474563 / Thesis (Ph.D.) -- University of Adelaide, School of Psychology, 2009

A desnutrição protéica precoce afeta as estruturas envolvidas nos mecanismos de comportamento, aprendizagem e memória. Desta forma, o objetivo deste trabalho foi avaliar o desempenho de ratos desnutridos em diversos procedimentos de memória de reconhecimento de objetos. Ratos Wistar machos (n=132) foram submetidos a dietas isocalóricas contendo 6% (Desnutridos) ou 16% de proteína (Controle) durante os primeiros 49 dias de vida. Foi imposto um período de recuperação nutricional do dia 50 a 70 de vida, quando os testes comportamentais foram iniciados. No Experimento I os animais foram colocados em uma arena com um objeto A. Após 3 ou 24 horas desta exposição, o rato retornou para arena com o objeto A e outro objeto B. O Experimento II foi conduzido com três diferentes procedimentos. No primeiro, o animal foi colocado na arena com três objetos diferentes. Após 24 horas desta exposição, o animal foi novamente colocado na arena com dois objetos já conhecidos pelo animal e um novo objeto. No segundo procedimento, os animais foram colocados na arena com dois objetos localizados nos cantos adjacentes da arena. Após 24 horas o animal retornou para a arena com um objeto na mesma posição e o outro objeto no canto diagonal da arena. No terceiro procedimento o animal foi colocado em um contexto A com dois objetos idênticos. Após cinco minutos, o animal foi colocado em um contexto B com dois objetos idênticos, mas diferentes quando comparados aos objetos apresentados no contexto A. Durante a fase de teste, o animal foi colocado em um dos dois contextos com um objeto do contexto A e outro objeto do contexto B. Foi calculado o Índice de Reconhecimento: IR = (tempo gasto no novo objeto/tempo gasto no objeto já conhecido+tempo gasto no novo objeto) X 100. Os dados foram submetidos ao Teste t Student para amostras independentes (p<0,05). Os resultados mostraram que os animais desnutridos apresentaram menores índices de reconhecimento quando comparados aos animais controle em todos os experimentos, sugerindo que a desnutrição protéica precoce prejudica a memória nos procedimentos de reconhecimento de objetos. / Early Postnatal protein malnutrition affects structures involved in the mechanisms of behavior, learning and memory. Thus, the aim of this work was to evaluate the performance of malnourished rats in several procedures of recognition memory for objects. Male Wistar rats (n=132) were submitted to isocaloric diets containing 6% (Malnourished) or 16% of protein (Control) during the first 49 days of life. A nutritional recovery period was imposed from 50 to 70 days of age, when behavioral tests started. In the Experiment I the animals were put in an open field with an object A. After 3 or 24 hours of this exposition, the rat returned in the open field with the object A and another object B. The Experiment II was conducted with three different procedures. In the first one, the animal was placed in the open field with three different objects. After 24 hours, the animal was replaced in the open field with two objects that were already known by the animal and a new object. In the second procedure the animals were placed in the open field with two objects located in the adjacent corners of the open field. After 24 hours the animal returned to the open field with an object in the same position and the other object in the diagonal corner of the open field. In the third procedure the animal was placed in a context A with two identical objects. After five minutes the animal was placed in a context B with two identical objects, but different when compared to the objects presented in the context A. During the test phase, the animal was placed in one of the two contexts with one object from the context A and another object from the context B. It was calculated the recognition index: RI = (time spent in the new object/time spent in the object already known + time spent in the new object) X 100. The data were submitted to a Student´s t test for independent samples (p<0.05). The results showed that malnourished animals presented lower recognition indexes as compared with control animals in all the experiments, suggesting that early protein malnutrition impairs memory in procedures of object recognition.

Current Signal Detection Theory models of source memory necessitate assumptions about the underlying distributions of source strengths to describe source memory performance. The current experiments applied a modified version of the same-different task in order to plot individual memory stimuli along a controlled dimension of the average frequency of voices. This technique allowed us to determine that subjects were using an independent-observations strategy rather than a differencing strategy when deciding whether two test words were spoken by the same or different female speakers at study. By including two male and two female voices and changing the task distinction from same or different speakers to same or different genders, we predictably switched subjects’ decision strategies. With this new same-different memory design, we are one step closer to ending our reliance on measures that are inferred from data to describe subjects’ source memory performance.

The remember-know paradigm is widely used in recognition memory research to explore the mechanisms underlying recognition judgments. The most intriguing question about the paradigm that needs to be answered is: Are the processes that underlie “remember” and “know” responses the same or different? The extant remember-know models provide different answers. The dual-process model (Yonelinas, 1994) assumes that “remember” and “know” judgments are made with qualitatively different underlying processes. The one-dimensional Signal Detection Theory (SDT) model (Donaldson, 1996; Hirshman & Master, 1997) and the Sum-difference Theory of Remembering and Knowing (STREAK) model assume that “remember” and “know” judgments are made with same underlying processes but different response criteria. In this thesis, three experiments were conducted to evaluate these models. The remember-know models were fit to the accuracy data to see which model provides the best account for the ROC data. In addition, the reaction time data were fit with ex-Gaussian distributions and the best-fit skew parameters were used to reveal whether the underlying strategic processes for “remember” and “know” judgments are same or not. The results of the remember-know model fit were mixed: In the first experiment with list length manipulation, 6 out of 8 cases were best fit with the one-dimensional models and the other 2 cases were best fit with the dual-process models; in the second experiment with list strength manipulation, 11 out of 18 cases were best fit with the one-dimensional models, another 6 cases were best fit with the dual-process models and the rest one case were best fit with the STREAK model; in the third experiment with response bias manipulation, 6 out of 16 cases were best fit with the one-dimensional models and the other 10 cases were best fit with the dual-process models. The results of ex-Gaussian fit to RT data supported the one-dimensional model better: for the subjects who provide enough overlapping data in comparison of the distributions of hits followed by “remember” and “know” judgments, the values of skew parameter did not differ for “remember” and “know” responses in 7 out of 8 cases. This indicates that the same process underlies “remember” and “know” responses.