Groundwater levels in the Wheatbelt of Western Australia are rising and causing severe and widespread land salinisation. Evidence from northern Victoria showed that episodic recharge pulses following floods had caused significant groundwater rises. The aim of this study was to determine: 1. whether episodic recharge was significant compared to regular recharge in the Wheatbelt; 2. the conditions under which episodic recharge occurs. (For complete abstract open document)

Patients with dementia due to Alzheimer's disease (AD) tend to exhibit impairments in in their episodic memory. In yes-no tests of recognition memory, patients with AD often display liberal response bias, a stronger tendency to recognize unstudied items as already-studied "old" items. Such tendency is believed to be related to false memory, which can decrease the quality of life in many AD patients. In this study, we analyzed the effect of different instructional manipulations within yes-no recognition memory task on response bias. Younger healthy adults, older healthy adults and one AD patient were evaluated for recognition memory performance and response bias in three different conditions of instructional manipulation. In each session separated by a week-long interval, participants were shown 120 words to study and 240 words, half of which were studied items, to be tested for recognition memory. Instructional manipulation was added in the testing phase of each condition. In one session, the participants were asked if the words were old, studied items; in another session, they were asked if the words were new, unstudied items; finally in the third session, participants were asked to identify if the words were either old or new. Our findings corroborated previous studies by observing liberal response bias in AD and moderately conservative response bias in health adults. We found that the instructional manipulations did not have a significant effect on response bias in either control group while the effect in the AD patient was inconclusive.

A healthy memory is essential to personal identity, completion of everyday tasks, and social acceptance. As factors such as age and illness threaten this key aspect of life, scientific and commercial attention has shifted to software, pharmaceuticals, and medical devices that help stave off inevitable memory decline. There is evidence suggesting that changes in lifestyle similarly work to improve memory. Mindfulness meditation, which is a practice rooted in the spiritual beliefs of Buddhism, has emerged as a promising technique to improve facets of cognition, including memory, as well as to change structures in the brain. Pattern separation is a key process of episodic memory that allows one to keep similar memories distinct. In this study, we evaluate the efficacy of a 4-week mindfulness training program on visual object pattern separation against an active creative writing control intervention and find that mindfulness meditation improves pattern separation and promotes changes in hippocampal brain structures.

The aim of this dissertation was to develop a novel behavioural method to assess young children’s capacity for episodic foresight. Specifically, I developed a marble game paradigm to assess whether 3-, 4-, and 5-year-old children would save marbles for future enjoyment. Study 1 demonstrated that preschoolers will save more spontaneously when they can draw on a recent past experience compared to when the context is completely novel. Results from study 1 also suggest that preschoolers are sensitive to the relative value of future rewards. Study 2 revealed that providing children with a verbal prompt alerting them to their possible courses of action (i.e., saving or spending) facilitated saving, that 5-year-olds saved more than 3-year-olds, and that children’s performance on this behavioural (i.e., nonverbal) measure of saving was independent of their language proficiency. Children’s saving was not associated with other capacities hypothesized to relate to episodic foresight (theory of mind, inhibitory control, and working memory). Implications for children's saving, the development of episodic foresight, and future research are discussed.

Thesis advisor: Scott D. Slotnick / Sex differences exist in both brain anatomy and neurochemistry (Cahill, 2006). Many differences have been identified in brain regions associated with long-term memory including the dorsolateral prefrontal cortex, hippocampus, and visual processing regions (Andreano & Cahill, 2009). There is, however, a paucity of research investigating whether and how these differences translate into differences in functional activity. Part 1 investigated sex differences in the patterns of functional activity in the brain during spatial long-term memory, item memory, memory confidence, and false memory. In addition, a meta-analysis was conducted to identify whether there were consistent sex differences in the brain across different long-term memory types. Part 2 determined whether there were sex differences in the patterns of functional connectivity in the brain during spatial long-term memory. Specifically, differences in functional connectivity between the hippocampus and the rest of the brain in addition to the thalamus and the rest of the brain were investigated. Finally, Part 3 investigated whether the observed differences in the patterns of activity (identified in Chapter 1) had sufficient information to classify the sex of individual participants. The results of Part 3 argue against the popular notion that the average female brain and average male brain are not significantly different (Joel et al., 2015). More broadly, the studies presented in this dissertation argue against the widespread practice of collapsing across sex in cognitive neuroscience. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.

Thesis advisor: Maureen Ritchey / Regulating negative emotions that arise while recalling an unpleasant event presents a persistent challenge. As a reconstructive process, recall offers an opportunity to ease the burden of repeated regulation by updating negative memories, with the potential for long-term reductions in the negative affect associated with a memory. However, little is known about the recall-related brain processes that support lasting effects of emotion regulation on episodic memories. Across three studies, the current project examined the behavioral and neural correlates of regulating emotionally negative memories. First, a stimulus database of real-life news videos optimized for studying naturalistic emotional memory was developed. Then, the behavioral effects of two emotion regulation strategies, memory reappraisal and memory suppression, were tested. Finally, functional magnetic resonance imaging (fMRI) was used to investigate the brain processes associated with lasting reappraisal-related changes in memory valence. We found that reappraisal was associated with lasting reductions in the negative valence of naturalistic memories, whereas suppression had no effect on memory valence. We also found that recall-related activity in lateral occipital cortex was associated with a reappraisal-mediated reduction in negative valence 24-hours after reappraisal. These results suggest that brain processes involved in the initial retrieval of negative content also support the emotion regulation of those memories, consistent with research showing that memory reactivation is critical for robust memory updating. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Psychology.

Atmospheric deposition (AD) is a significant but poorly understood source of nutrients to many aquatic systems around the world. Accurate characterization of the nutrient budgets of aquatic systems is critical to good management decisions, so a better understanding of AD-related nutrient loads is essential, especially for water bodies where nutrient loads from atmospheric deposition are significant. Due to its large surface area, proximity to Great Basin dust sources, high values of atmospheric particulates due to inversions, and the high phosphorus content of local soils, Utah Lake, in the semi-arid Utah Valley, USA, experiences significant phosphorus loading from AD. The lake is eutrophic and has a history of impaired water quality and HABs, which has motivated significant study and debate over nutrient loads to the lake. Previous studies that measured phosphorus AD to Utah Lake showed a large portion of the AD was associated with a few high-volume deposition events, with the data exhibiting unexpectedly high peaks at some locations on a few dates. These issues cast doubt on the data. We used statistical analyses and machine learning models to characterize AD to Utah Lake. In addition to determining the distribution of AD events, we analyzed the relationship between phosphorus AD and local weather events. We used this analysis to determine whether the high phosphorus measurements were outliers due to sampling errors or represented actual conditions. Our analysis shows that AD events followed an XXX distribution, similar to the distribution of precipitation events on the lake. We found the high phosphorus deposition events were correlated with instances of high wind occurring when the ground was dry. We also observed regular cycles of higher and lower measurements throughout the year that are like measures of atmospheric particulate matter. We conclude that atmospheric phosphorus deposition on Utah Lake is episodic and driven by weather conditions around the lake, with the most important factors being the number of hours with high winds during a collection period and the percentage of those hours where the ground was dry during a collection period followed by dry deposition from particulate matter. This is an important finding for the management of Utah Lake and also has implications for the management of other eutrophic lakes in which atmospheric deposition of nutrients impacts water quality.

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The current study was conducted with a sample of 253 college undergraduates to extend the findings in the existing research on motivational models of alcohol and marijuana use. Specifically it was intended to evaluate the relative benefits of assessing motives for using these drugs during a specific episode rather than in the dispositional fashion utilized in virtually every existing study on the subject. Affect regulation aspects of the motivational model were further explored by measuring state (rather than trait) affect immediately preceding a use episode. A timeline follow-back method was used to identify the most recent use episode and to assess recent quantity of use and negative consequences in greater detail. The similarity of the types of motives derived from episodic assessment to those seen dispositionally lends further credence to the validity of DUM subtypes, their distinct pathways to use and related problems, and the affective-motivational model as a whole. Affective states (rather than just traits) played a significant role in the motives endorsed and outcomes. Previous findings on the direct effects of drinking to cope on the development of problems were confirmed on an episodic level. Finally, episodic assessment appeared to have some utility above and beyond that of dispositional assessment when examining specific episodes of use. / Ph. D.

Episodic memory is a critical component of human cognition. Episodic memory involves recollection of the contextual details surrounding an event, the capacity for mental time travel of past and future events, and is characterized by the subjective awareness that an event has been personally experienced. It is fundamental to our understanding of this complex memory system to examine how episodic memory emerges during the course of development. The present investigation explored the developmental improvement in episodic memory processing assessing recollection of factual information and the source of this information (i.e., source memory) between early to middle childhood. The electrophysiological (EEG) correlates of fact and source memory processing and measures of executive function were also examined as potential sources of variation in episodic memory. The focus of Study 1 was to examine source memory development in early childhood in a sample of 4- and 6-year-olds. Results revealed that older children were better able to recall both fact and source information. Source memory measures were correlated to early executive ability, namely measures of working memory, inhibitory control and set-shifting. Frontal EEG accounted for unique variation in fact recall but not source recall, whereas temporal EEG did not predict fact or source recall performance. The focus of Study 2 was to examine source memory development in middle childhood in a sample of 6- and 8-year-olds. Older children were better on fact recall, but both ages were comparable on source recall. Frontal EEG uniquely predicted fact recall performance beyond the contribution of age and language. Both frontal and parietal EEG and executive function predicted variation in source recall performance. In contrast, temporal EEG did not uniquely predict fact or source recall performance. Lastly, Study 3 was a longitudinal investigation of source memory between early and middle childhood. Although age-related increases in performance were evident, Time 1 and Time 2 source memory measures were not correlated. This investigation contributes to our understanding of the developmental changes in source memory processing between early and middle childhood, and identifies that patterns of frontal and parietal brain activity and executive function skills contribute to early episodic memory formation. / Ph. D.