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Publication Search Results

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Overgeneral autobiographical memory in depression: a three-level meta-analysis

(Georgia Institute of Technology, 2021-12) Weiss-Cowie, Samuel Aaron

Overgeneral Autobiographical Memory (OGM) is a frequently studied phenomenon in major depressive disorder (MDD). Although there exist several meta-analyses on OGM and MDD, their emphasis on clinically diagnosed current depression leaves open question about the severity of OGM in subthreshold and remitted depression. In addition, numerous studies of OGM have remained unconsidered due to a focus on one testing paradigm, the Autobiographical Memory Test (AMT). To address these gaps, we conducted a meta-analysis on OGM in MDD that included remitted, subthreshold, and currently depressed samples and incorporated non-AMT studies. In addition, we used three level models for the first time, which enabled robust variance analyses including multiple effect sizes from each study while controlling for dependencies across those effect sizes. With results from a total of 67 published and unpublished works, ours is the largest meta-analysis to date on OGM in depression. We simultaneously identified decreased autobiographical memory specificity (g = -0.73) and increased categoricity (g = 0.77) for depressed individuals compared to controls. Moderator analyses suggested that OGM is more severe in current, clinical MDD than subthreshold and remitted depression, while OGM is similarly severe for positive, neutral, and negative memories. Our results resolve longstanding debate surrounding the relationship between valence and OGM while emphasizing the importance of utilizing a broader range of testing paradigms and considering non-clinical depression in future work.
A Large Online Study Examining Individual Differences in Sleep Quality and Episodic Memory Performance Across the Adult Lifespan: Interactions Between Psychosocial and Sociodemographic Factors

(Georgia Institute of Technology, 2021-07-30) Hokett, Emily

The relationship between sleep quality and episodic memory performance, or memory for the details of past events, has been established in young and older adults. Although the sleep-memory relationship is similar across age groups, older adults tend to experience poorer sleep quality than young adults. Similarly, both young and older racial/ethnic minorities experience poorer sleep quality as compared to non-Hispanic Whites. Certain lifestyle factors may protect against these age and racial/ethnic group sleep disparities and moderate sleep-memory associations. Here, I recruited a 279-participant online sample of racially diverse adults (29% Black). I assessed self-reported sleep quality and associated cofactors, including physical activity, social support, race-related stress, and religiosity. I found no significant age or racial differences in sleep quality nor memory performance. However, Black participants reported greater religiosity. Moreover, Black participants demonstrated stronger associations between larger social networks and better sleep quality than White participants. Across age and racial groups, protective factors moderated the sleep-memory association such that greater endorsement of protective lifestyle factors was linked to reduced sensitivity to sleep for better memory retrieval. Conversely, low social support was linked with stronger associations between poor sleep quality and poor memory performance. In brief, protective factors, such as social support and religiosity may protect against age and race-related sleep disparities as well as the cognitive consequences of poor sleep.
Neural Correlates of Emotional Memory as a Function of Age and Depressive Symptoms

(Georgia Institute of Technology, 2021-07-29) James, Taylor

Age-related positivity effects are well established in the literature. Positivity effects in memory are represented as greater benefits for positive over neutral material and/or reductions in the benefits for negative over neutral material with age. However, it is unknown if positivity effects are limited to older adults without depressive symptoms. In the current fMRI study, individuals ages 18-76 with a range of depressive symptom severity were scanned as they rated the emotional intensity of positive, neutral, and negative images that were preceded by cues to signal the valence of the upcoming image. Participants subsequently completed a recognition memory task outside of the scanner. Behavioral, univariate, representational similarity, and functional connectivity analyses provided evidence for interactive effects between age and depressive symptoms. For instance, at low levels of depression, typical patterns in aging emerged: younger age was associated with better memory for negative than neutral images, and this memory benefit for negative material was reduced with older age. With increasing levels of depression, however, there was a reduction in the positivity effect, manifesting as improvements in negative relative to neutral memory. The neural data highlighted mechanisms that may underlie these interactive effects, including reductions in prefrontal cortex functional connectivity associated with downregulation of negative affect. Together, these findings suggest that depressive symptoms in older adulthood reduce positivity effects through alterations in neural networks underlying emotion regulation.
Sex-related differences in resolving proactive interference during associative memory tasks

(Georgia Institute of Technology, 2021-05) Quadri, Ayesha

Prior studies have shown that males and females perform differently on a variety of memory tasks. It is suggested that certain biological factors can lead to sex-related differences in cognitive decline, memory, and learning. The present study explores this further by examining the performance of males and females on associative memory tasks when exposed to proactive interference (PI). The findings of this study may aid in understanding the underlying mechanisms involved in overcoming interference and improving memory. This study utilized 49 individuals (F = 26, M = 23) between the ages of 18 and 77. The participants were asked to complete associative memory tasks while exposed to varying levels of interference (high interference, low interference, or no interference). During the encoding portion of the memory task, participants were asked to determine the ease in which two images presented together could be imagined. During the retrieval portion of the memory task, participants were asked to recall which associate category (face or scene) the presented object was most recently paired with in the encoding phase. Electroencephalography (EEG) data was also collected while the participants completed the memory tasks, but due to time-constraints and limitations introduced by the COVID-19 pandemic, this data was not analyzed. A 3x2 repeated measures ANOVA conducted found a significant main effect of interference on memory accuracy, but no significant difference in the effects of interference on the memory accuracy of both sexes. Additionally, no interaction between interference conditions and sex was found. However, a paired samples t-test found significant differences in memory accuracy between the three interference conditions used in this study. Given this, future studies may modify components of this study to observe sex-related differences, such as changes to the associative memory task or an increase in the sample size. In the future, the potential analysis of EEG data may shed light onto differences in neural activity between the two sexes when exposed to PI.
Investigating Various Approaches in Classification of EEG Signals Representing Distinct Cognitive States to Reach an Optimal Solution

(Georgia Institute of Technology, 2021-03-02) Mirjalili, Seyedsoroush

There are various cases in which cognitive neuroscientists might be interested in exploring the neural differences associated with distinct cognitive states such as whether an individual has remembered some information or not. While it is common to use event-related potentials (ERPs) to distinguish neural activities representing different cognitive states, it does not allow us to explore single events because of its averaging nature. Classification of brain states associated with single events using real-time signals holds great potential for real-world applications such as brain-computer intervention systems that could support everyday learning. However, the progress in reaching high classification accuracy is still in early stages and thus, moving to the next step and creating such interventions is not possible yet. Moreover, previous studies applying classification methods to decode cognitive states have not typically compared different methods or explained the reasons for their choices. As a result, in this study, I systematically compared different methods of feature extraction, feature selection, and choice of classifier in the same study to investigate which methods work the best for decoding different episodic memory and perceptual “brain states.” Using an adult lifespan sample EEG dataset collected during encoding and retrieval of objects paired with color and scene contexts, I found that the Common Spatial Pattern (CSP)-based features could distinguish the trials of different memory classes (i.e. item remembered vs. forgotten; context correct vs. incorrect; red vs. green vs. brown context perception) better than other types of features (i.e., mean, variance, correlation, features based on AR model, and entropy), and the combination of filtering and sequential forward selection was the optimal method to select the effective features. Moreover, Bayesian classification performed better than other commonly used options (i.e., logistic regression, SVM, and LASSO). These methods were shown to outperform alternative approaches for an orthogonal dataset, supporting their generalizability. My systematic comparative analyses allow me to offer some recommendations for cognitive researchers to consider when applying machine learning based classification to their datasets.
Encoding Differences in Aging Adults can Explain Associative Memory Deficits

(Georgia Institute of Technology, 2020-05) McClelland, Lauren

The relationship between aging and associative memory decline has been well-established in literature, however there is no clear reasoning for this decline. Recent functional magnetic resonance imaging (fMRI) studies have shown that aging adults show decreased neural specificity across the cortex, now commonly termed dedifferentiation. The current research attempts to find a relationship between increased dedifferentiation with age and their resulting decreases in associative memory performance. By utilizing multi-voxel pattern analysis (MVPA) classifiers, the level of neural distinctiveness of the variably aged adults can be quantified and compared to associative memory performance. We found that neural distinctiveness was decreased with age as well as retrieval of increasing levels of specificity of associate items. This suggests that the associative memory decline in older adults can be explained by a decrease in neural specificity for the specifics of associate items during encoding.
Investigation of the relationship between the negative affect in young adults and depression

(Georgia Institute of Technology, 2020-05) Kamat, Anchal

Young adults display the negative affect where they pay attention to and remember negative information better than positive information. A similar affect is in observed in individuals with depression. Since depression is prevalent in young adults, this bring into question whether there is a connection between the negative affect in young adults and depression. This study explores this phenomenon by using fMRI imaging to identify any patterns of activation involved in the relationship between depression and the negative affect in young adults. To achieve this, 13 young adults between the ages of 18 and 34 years old were recruited. After confirming that they are fMRI safe, a set of neuropsychological assessments and depression questionnaires were carried out, followed by an fMRI Encoding Task. During the Encoding Task participants are presented with a positive, negative, or neutral auditory cue and an imaging matching its emotional valence. They were then asked to evaluate the emotional intensity of the picture. After the fMRI a Retrieval Task where individuals asked if the image is new or old and then how confident they are in their decision. Behavioral analysis of memory accuracy with a repeated measures ANOVA resulted in no significant differences in the memory for any of the conditions. ANOVA analysis of the fMRI images with an uncorrected voxel threshold of .001 also showed no significant activation patterns. Overall, this study was not able to achieve its goal due to time restrains. As this is an ongoing project, greater analysis will be utilized to identify a relationship between the experimental conditions and brain activity.
Age-related changes in resolving proactive interference in associative memory

(Georgia Institute of Technology, 2019-11-27) Corbett, Brittany L.

Previous research has found that older adults are more susceptible to proactive interference. This is likely due to age-related deficits in the PFC-mediated cognitive control processes recruited to resolve interference. The current functional magnetic resonance imaging (fMRI) study investigated if age-related deficits in PFC-mediated cognitive control processes underlie age-related differences in the resolution of proactive interference in an associative memory task. Young and older adults were tasked with remembering which associate (face or scene) objects were paired with most recently during study, under conditions of high, low or no proactive interference. Following scanning, participants’ memory was tested for varying levels of episodic detail about the pairings. Young and older adults were similarly susceptible to proactive interference. Memory for both the general target category and the specific target associate worsened as the level of proactive interference increased, with older adults having moderately worse memory for the specific target associate. Across age, the left-VLPFC showed increased recruitment for increasing levels of interference at encoding suggesting that older adults are able to spontaneously engage in post-retrieval selection to the same extent as young adults. At retrieval, older adults recruited the vmPFC more than young adults during remembered low interference trials but similarly recruited the vmPFC during remembered high interference trials. In line with the CRUNCH model, this suggests that older adults need to engage in more monitoring for low interference items, but engage in a similar amount of monitoring to young adults for high interference items, suggesting that successfully resolving high interference is equally difficult for both young and older adults.
Whole-Brain Gray Matter Volume as an Anatomical Predisposition for Cognitive Ability

(Georgia Institute of Technology, 2019-05) Sheikh, Asif

The human brain is the topic of much interest in recent years, and due to the advent and rising popularity of imaging techniques such as functional MRI, we are able to understand the brain with greater detail than ever before. Cognitive ability has always been known to be heavily tied to neuroanatomy, and existing research has shown that although cognitive skill is heavily dependent on specific brain regions such as the dorsolateral prefrontal cortex or hippocampus it is a highly delocalized function that involves the use of numerous brain regions. Larger volumes of whole-brain gray matter has also been shown to be tied to greater success on cognitive assessments implying that volumetric estimations of gray matter can serve as an indication of cognitive ability. Brain volume varies between individuals for a variety of reasons such as sex, age, ethnicity, and socioeconomic status. The former three of these are well understood biological principles or processes, but the last of these is a societal effect on physiology and may include diet and nutrition, education and social development, or occupation and family life. This paper will also examine whole-brain gray matter volumes in respect to education. Subjects (n = 60) were imaged to collect T1-weighted fMRI structural scans and were given Memory Assessment Scales examinations afterwards. We performed voxel-based morphometry using DARTEL in Statistical Parametric Mapping on the fMRI structural scans to acquire the volumes of gray matter, white matter, and cerebrospinal fluid of each individual. These gray matter volumes were then related to the individual’s performance in a variety of cognitive domains tested for by the Memory Assessment Scales to examine if increasing gray matter volume has an effect on the individual’s performance. Years of education was also related to gray matter volume to observe if higher volumes correlated with higher education. Our findings suggest that gray matter does indeed demonstrate a small increase performance in some but not all cognitive domains tested for. The correlation with years of education pursued obtained was minimal, however it became slightly more pronounced in older individuals when the subjects were divided by age group. The brain volumes of the younger age group were determined to be statistically different from the older age group, but when these age groups were divided into high and low education classifications, the brain volumes from the two groups were not shown to be statistically different from each other. This indicates to us, that gray matter volume has a negligible effect on level of education pursued despite its seemingly positive effect on cognitive performance. It is important to understand that the mechanisms behind cognition are incredibly complex involving innumerable factors and that further exploration must begin at the biological level to expand our understanding of this phenomenon.
The influence of valid and invalid context memory cues at encoding

(Georgia Institute of Technology, 2018-10-24) Strunk, Jonathan

Previous episodic memory studies have found that neural activity preceding a to-be-encoded event can reflect subsequent memory performance. This neural activity is thought to reflect the preparatory engagement of cognitive processes related to the specific task characteristics. It is currently unknown if the preparatory activity reflects a benefit to successful encoding or is epiphenomenal; such that trials in which the participant engages in preparatory processes are also trials for which the participant is actively engaged and more likely to successfully encode. Numerous attentional orienting and detection studies find that accurate preparation improves performance by biasing the relevant neural regions and processes. These studies also show that inaccurate preparation can bias competing regions and processes which lead to impairments in performance. This dissertation directly tests the influence of preparation on successful encoding, by manipulating the accuracy of preparation. If preparation directly influences processing the to-be-encoded information, then there should be a benefit to accurately preparing with trial relevant information and a cost to preparation with inaccurate information. But, if preparation is solely epiphenomenal, then the utility of preparation should not influence successful encoding. In the dissertation, I paired items with one of four context scenes during an associative memory task. On each trial, a prestimulus cue was presented that indicated either a context scene with a text label or an uninformative neutral label. The context label cues predicted which scene would be paired with the item. For valid cue trials the cued scene was presented with the item, and for invalid trials the cued scene was not the same as the presented scene. In order to encourage strategic use of the cues, an additional required cue condition was included where a scene was not presented with the item. This paradigm allows for the assessment of preparation without task or stimulus confounds, as it directly assesses accurate and inaccurate preparation while hold task and stimulus characteristics constant within the cue – stimulus interval across cue conditions. Before the encoding task, a familiarization task was used to associate specific context cue labels with specific scene images. During retrieval, old and new items were intermixed, and participants indicated if the item was new or selected the associated scene. A second question asked for their confidence in the retrieval decision. Neural oscillations were used to assess neural activity related to successful subsequent context memory performance. Overall, I found that accurate preparation improved context memory performance and that invalid cues placed greater demands on successfully encoding the correct context. In addition, inaccurate preparation interfered with processing the presented scene compared to trials with a valid cue. During context memory retrieval, the results suggest that participants who did not resolve the interference from the invalid cue at encoding had worse context memory performance. Thus, the utility of preparation during encoding has a direct impact on memory performance.