Browsing by Subject "Working memory"
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Item Adaptive forgetting with uncontrolled and controlled removal processes(2020-08-17) Kim, Hyojeong; Lewis-Peacock, Jarrod A.; Preston, Alison R.; Joseph, Joseph E.; Banich, Marie T.Memory is essential to guide our behavior by which goal-relevant information is accessed in an accurate and timely manner. One of the fundamental cognitive abilities to accomplish such function is to remove unnecessary information from long-term memory and outdated thoughts from working memory. Removing information facilitates information processing in service of the goal-directed behavior by reducing the potential interruption from the irrelevant information and thus increasing cognitive capacity. The research in this dissertation focuses on the removal of information as adaptive memory operations in both unintentional (“bottom-up” implicit learning) and controlled processes (“top-down” cognitive control). To identify the neural mechanisms of removal and link these to specific behavioral outcomes, my approach relies on using functional MRI (fMRI) with multivariate pattern analyses (MVPA). Experiment 1 demonstrated how the automatic learning that generates memory-based predictability alters long-term retention of the memory. While unreliable predictions, which violated real outcome, were more likely forgotten, more generic predictions that matched the outcome in an abstract level were retained. Experiment 2 tested neural consequences in different removal methods that recruit top-down cognitive control in working memory. The different removal operations employed distinct neural systems and removed the representation of item being removed from working memory with different speeds as well as with different impacts on memory capacity. Building upon Experiment 2, Experiment 3 examined representational changes during these removal operations in the ventral visual cortex and hippocampus. While sensory representations reflected different attentional states depending on removal operations, hippocampal representations reflected top-down inhibitory regulation states. The findings also suggest that these removal operations lead to qualitative alterations of representation, which implies different long-term memory forgetting. As a whole, the research in this dissertation is seeking to improve our understanding of memory removal in two key ways: (1) define the role of implicit processes in prediction-based forgetting from LTM, and (2) precisely characterize the control and consequences for multiple operations of removing information from working memory.Item Altered functional connectivity during working memory performance in older adults following low-level laser therapy(2020-08-13) Hickson, Brennan Ouida; Haley, Andreana P.; Harden, Kathryn PMost current interventions for improving cognition in older adults have proven unsuccessful in producing enduring effects, though non-invasive brain stimulation techniques including low-level laser therapy (LLLT) show promise in this regard. The aim of the present study was to determine whether or not physiological changes involving the right superior frontal gyrus, following its stimulation via LLLT, could induce changes in working memory, as measured by a multilevel in-scanner N-back task. Ninety-eight adults (ages 45 and over) with (n = 36) and without (n = 62) mild cognitive impairment were included in this study. It was hypothesized that, relative to adults receiving placebo, individuals treated with LLLT would exhibit strengthened load-dependent functional coupling between this region and other brain regions involved in WM leading to better performance accuracy and faster reaction times on the N-back task. Results showed no differences in performance accuracy (t = 1.02, p = 0.312) or reaction times (t = -0.82, p = 0.413) between treatment groups. Functional connectivity between the right SFG and bilateral occipital gyri and bilateral precuneus regions was strengthened in those who received LLLT but reduced in the placebo group. The LLLT group exhibited reduced functional coupling between the right SFG and paracentral lobule, cingulate cortex, precentral gyrus, middle frontal gyrus, and insula, whereas these connections were strengthened in the placebo group. The absence of change on behavioral outcome measures makes it difficult to contextualize these physiological changes, but the findings seem to suggest excessive engagement in the task following treatment, as well as insufficient deactivation of the default mode network. Follow-up studies are necessary to determine the capacity of LLLT to improve cognition in other domains not investigated by the present study. As well, further insight into the potential of LLLT could be gained through investigations of LLLT in conjunction with cognitive training interventions, as is often the case with alternative neurostimulation therapies.Item Circuit mechanisms of persistent activity in the primate cortex during working memory(2019-05-13) Hart, Eric Lewis; Huk, Alexander C.; Hayhoe, Mary M; Mauk, Michael; Nauhaus, Ian M; Aldrich, Richard WWorking memory is the cognitive ability to actively maintain and manipulate information on the timescale of seconds. Neurons in the prefrontal and posterior parietal cortices of the primate brain remain active in absence of sensory input and appear to correlate with working memory. In this thesis, I investigate the mechanisms of persistent activity during working memory in the frontoparietal network of the macaque. By conducting simultaneous electrophysiological recordings in two of the key regions of this network, the lateral intraparietal area (LIP) and the frontal eye fields (FEF), and employing statistical models of the neural population activity, I characterized the interactions between neurons locally in each area and between these two distant brain regions. In a visuospatial working memory task, during which the subject must remember the spatial location of a target, I found strong recurrent activity on single trials both within and between these areas that was not due to the visual stimulus or the motor response. The strength and timescale of functional interactions between LIP and FEF were highly reciprocal and symmetrical, providing evidence for the theory that reverberatory activity in this circuit does, in fact, support working memory. However, contrary to current models of the frontoparietal network, area LIP exhibited greater local recurrent excitatory activity than FEF, and many individual neurons in LIP displayed activity on longer timescales. In addition, the concurrent population activity had a greater impact on the spiking activity of most neurons than each individual neuron’s own intrinsic drive, especially in LIP. This result further emphasizes the role of network mechanisms in generating and maintaining persistent activity. Taken together, these findings suggest revisions to the current models of working memory, and highlight the importance of studying population activity on single trials.Item Consistent performance differences despite manipulation of cue switching variables in children and adults(2015-08) Bodenhamer, Jessie Raye; Church-Lang, Jessica; Maddox, ToddTo compare the stability of task-switching abilities across children and adults, we created a task with four goals in mind. First, we aimed to test whether certain task manipulations would reduce differences in adult and child performance. We created a nine level switching task, with changes in response choice consistency, number of response choices, and number of cued tasks. Second, we wanted to assess possible performance transitions within the child age group. We did this by subdividing the child group into smaller age bins. Third, we aimed to measure any short-term improvement across the study session. To do so, we compared responses from the first level of the task to an identically formatted level 10. Finally, we created a second study to investigate the effects of a higher working memory demand With respect to our first goal, attempts to reduce differences in adult and child performance were largely unsuccessful; children were consistently slower, less accurate, and more affected by task-level manipulations than adults. Our performance assessment within the child group identified a transition where participants as young as 12 years in Experiment 1 and 14 years in Experiment 2 displayed more adult-like responses in response times. In both studies, as the child age increased, we observed gradual improvement in accuracy. Regarding our third goal, we found similar amounts of improvement in both response time and accuracy for both adult and child groups, despite the high starting level of performance in adults in both studies. Added cognitive demand in Experiment 2 promoted significantly more improvement in both age groups. Thus, these novel tasks temporarily improved task-switching abilities in children and adults within a single session. As a whole, these results reveal consistent differences in task switching performance between age groups, but also relative flexibility (in the short-term) within a given individual.Item Determining fundamental mechanisms of oculomotor working memory(2022-05-05) Carney, Hayden C.; Huk, Alexander C.; Nauhaus, Ian; Geisler III, Wilson S; Hayhoe, Mary M; Mauk, MichaelOculomotor working memory tasks are known to generate persistent activity in regions of the primate brain, including the lateral intraparietal area (LIP). This persistent activity is thought to reflect the active maintenance of behaviorally relevant information. The mechanisms that underlie this persistent activity have been the focus of a great deal of research, but several key principles remain untested due to practical difficulties recording from these circuits in the macaque. To address this issue, we implanted chronic high density electrode arrays in the common marmoset, an emerging model species amenable to large-scale recordings. However, while marmoset LIP has been firmly localized, few studies have functionally explored marmoset parietal cortex and their ability to perform oculomotor working memory tasks was unknown. In this thesis, I developed methods for training marmosets to perform memory-guided saccades and characterized the activity of LIP during this task. I found strong visual and saccadic activity, as well as evidence of persistent activity comparable to macaque LIP, establishing marmoset LIP during memory-guided saccades as a viable model for studying persistent activity. This project was greatly aided by the development of a novel “supersession” analysis method with Jens-Oliver Muthmann and others that allows units on chronic arrays to be easily tracked over weeks or months of behavioral sessions. In addition, I have helped adapt numerous techniques for use in the marmoset, including 2-photon calcium imaging and ultraflexible electrode arrays. Combined with the behavioral paradigms we developed, these approaches will allow persistent activity in primate cortex to be studied in ways that have previously been infeasible.Item Does time perception underlie delay discounting?(2013-08) Berman, Rachel Elisabeth; Tucker, David M., 1953-; Carlson, Caryn L.Delay discounting, the belief that rewards decline in value over time, is a phenomenon observed in several clinical disorders, including Attention Deficit / Hyperactivity Disorder (ADHD), substance abuse disorders, and other impulse control disorders. Delay discounting behavior is characterized by a tendency to choose smaller, more immediate rewards over larger, more delayed rewards. This tendency has been associated with behavioral impulsivity and inability to delay gratification observed in the aforementioned clinical disorders. It has been suggested that time perception may be a salient feature of delay discounting. If the larger, longer-term reward is perceived as being more temporally remote, its relative value decreases and is associated with greater cost, and one becomes more likely to choose the more immediate reward over the longer-term (though optimal) choice. Time perception has been studied in clinical populations, with increased variability of responses as well as both under-production and overestimation of time intervals observed in those with ADHD and other disorders associated with impulsivity. The present study used informational feedback via a metronome to change belief regarding duration of a second--either increasing or decreasing it by approximately 20%. Participants were 132 college-aged students with and without a diagnosis of ADHD. Measures of impulsivity and ADHD symptomatology were collected as well, and participants completed several cognitive tasks measuring working memory and processing speed to explore the impacts of these measures on delay discounting and time perception. While participants were able to reliably incorporate the altered second belief into short estimations of time (i.e., less than a minute), the manipulation failed to generalize to longer-duration temporal estimations, and it did not affect delay discounting. Neither ADHD symptomatology, impulsivity, nor performance on the cognitive tasks were related to delay discounting behaviors, though a working memory measure was correlated with baseline (pre-manipulation) time and one longer duration estimation. This lends support to a relationship between working memory and temporal perception, though the relationship between temporal perception and delay discounting remains elusive. Directions for future studies to clarify the role of temporal processing and ADHD in delay discounting are discussed.Item Dynamics and outcomes of strategies used for prospective remembering(2020-09-17) Koslov, Seth Ryan; Lewis-Peacock, Jarrod A.; Preston, Alison R; Schnyer, David M; Scullin, Michael KProspective memory (PM) is our ability to remember to perform actions at specific times in the future despite other concurrent demands for our attention. Previous research has posited that there are two dissociable strategies that individuals use when trying to perform PM tasks: proactive and reactive control. Proactive control is characterized by the effortful processes of strategic monitoring of the environment for cues related to performing prospective intentions as well as maintaining a sustained representation of the PM-intention. Conversely, reactive control is characterized by the formation of cue-intention associations, which are stored in episodic memory until a cue in the environment triggers the spontaneous retrieval of the to-be-performed action. While previous research has been instrumental in dissociating these two PM strategies, we still do not know the manner in which individuals shift between strategies. Furthermore, little is known about how PM strategy flexibility influences our ability to carry out future intentions. The work in this dissertation investigated how individuals adjust PM strategy in response to environmental demands and how that flexibility relates to the subsequent ability to perform PM intentions. The work presented in this dissertation investigated the relationship between PM strategy, ongoing demands, and PM performance across three experiments. The first experiment investigated if and how individuals adjust PM strategy as ongoing demands gradually increased or decreased, and how those shifts related to subsequent PM performance. Results indicated that individuals adjusted their PM strategy in a fluid manner in response to changes in ongoing task demands. Additionally, these changes were adaptive, as they were related to subsequent PM performance. Experiment 2 investigated how strategy flexibility was related to the probability of a PM-event occurring. Results from that experiment revealed that individuals demonstrated greater shifts in PM strategy when the probability of a PM event was high compared to when it was low. Additionally, it was observed that adaptive strategy use was often related to better PM performance. In experiment 3, eye-tracking was used to more specifically characterize the monitoring component of proactive control, specifically relating eye-tracking measures to the oft used behavioral measure used to infer PM strategy, PM cost. Results from the experiment revealed that the relationship between strategic monitoring and PM costs shifted as a function of ongoing task difficulty, with costs being more closely related to measures of strategic monitoring when ongoing demands were low than when they were high. Additionally, the results indicated that while monitoring was important for prospective remembering, it did not fully explain subsequent PM performance differences. Overall, the results from these three experiments demonstrate that individuals do gradually and fluidly adjust the amount of effortful resources devoted towards prospective remembering in response to demands of the environment. Furthermore, these results extend our knowledge of how individuals implement strategy shifts, as well as our understanding of how shifts in strategy serve adaptive purposes.Item Exploring the interactions between affective auditory distractions and working memory(2024) Koganti, Sannidhi; Lewis-Peacock, JarrodIn our daily lives, the ability to focus on tasks while filtering out distractions is crucial. Attention and working memory play pivotal roles in this process, but distractions, particularly emotional stimuli, can still interfere. Working memory is susceptible to impairments when dealing with emotional distractions, which can have implications for emotional regulation and overall well-being. Negative emotional distractions, in particular, have been shown to interfere with cognitive task performance. However, the impact of affective distractions lacks a consensus in terms of how they interact with working memory performance. Further, the range of acoustic stimuli used as affective distractors is limited, often confined to brief, task-irrelevant sounds, which may not always be applicable to real-world scenarios. In the current study, participants were asked to reproduce the colors of three images presented to them in order of their confidence in their ability to successfully reproduce the correct color. Additionally, the research incorporated prolonged exposure to distraction with the presentation of emotional auditory distractions in the form of news reports. Results showed that the presence of auditory distractions increased participant reports of being off-task. Further, memory errors were higher in the distraction conditions when compared to the no distraction conditions during the last response, when participant confidence was low. The findings suggest that there is a relationship between participant confidence and the interference of emotional auditory distractions. This study underscores the need to consider emotional distractions, particularly auditory stimuli, in real-world scenarios to better comprehend their effects on working memory and cognitive functioning.Item Language proficiency, test anxiety and their effect on working memory capacity(2022-04-22) Alarcon, Tania V.; O'Bleness, Jessica J.; Rodriguez, Erin M.Abstract: English language proficiency and test anxiety among Spanish speakers might affect performance on working memory (WM) tasks, not taking this into consideration, could result in the unreliable measurement of true WM capacity and true ability on tasks that require WM involvement. WM was defined as a system with a limited storage and temporal capacity for information-processing, which also involves attentional control and manipulation of information (Baddeley, 2003). WM performance has been found to be positively affected by bilingualism on WM tasks requiring attentional control (Engle, 2002). Furthermore, the information processing aspect of WM has been found to be negatively affected by test anxiety (Lee, 1999). As such, the present study is aiming to investigate the effects of test anxiety on working memory performance among Spanish/English speakers. The study will use a t-test, analysis of variance, and multiple regression to explore results.Item Long-term memory guides resource allocation in working memory(2021-06-29) Bruning, Allison Lee; Lewis-Peacock, Jarrod A.Working memory capacity is incredibly limited and thus it is important to use this resource wisely. Prior knowledge in long-term memory can aide in efficient encoding of information by allowing for the prioritization of novel stimuli over familiar ones. Here we used a full-report procedure in a visual working memory paradigm, where participants reported the location of six colored circles in any order, to examine the influence of prior information on resource allocation in working memory. Participants learned that one of the items appeared in a restricted range of locations, whereas the remaining items could appear in any location. We found that participants’ memory performance benefited from learning this prior information. Specifically, response precision increased for all items when prior information was available for one of the items. Responses for both familiar and novel items were systematically ordered from highest to lowest precision. Participants tended to report the familiar item in the second half of the six responses and did so with greater precision than for novel items. Moreover, novel items that appeared near the center of the prior location were reported with greater error than novel items that appeared elsewhere. This shows that people strategically allocated working memory resources by ignoring information that appeared in predictable locations and prioritizing the encoding of information that appeared in unpredictable locations. Together these findings demonstrate that people rely on long-term memory not only for remembering familiar items, but also for the strategic allocation of their limited capacity working memory resourcesItem Longitudinal effects of working memory on internalizing and externalizing behavior problems(2010-08) Low, Justin Alan; Keith, Timothy, 1952-; Tharinger, Deborah; Carlson, Cindy; Beretvas, Susan; Anderson, EdwardSeveral research studies have examined the link between working memory ability and behavior problems in youth. Research suggests that children with working memory deficits demonstrate lower levels of attention and higher levels of hyperactivity, physical aggression, and other behavior problems. The purpose of this research was to determine the effects of developmental trajectories of working memory on the developmental trajectories of behavior problems. Results suggested that developmental increases in working memory did not lead to developmental decreases in behavior problems. Results from this study suggested that internalizing and externalizing behavior problems increase over the course of childhood. Several variables did lead to developmental change in behavior problems in children. Children who had lower initial levels of working memory increased in internalizing behaviors less than children with higher initial working memory ability. Also, high socioeconomic status led to smaller increases in internalizing and externalizing behavior, high Peabody Picture Vocabulary Test (PPVT) scores led to larger increases in internalizing and externalizing behavior, and high PPVT scores led to larger decreases in inattentive and hyperactive behavior. Results are discussed in reference to current theories about working memory and behavior problems.Item Modulation of implicit working memory in temporal grouping(2010-08) Paine, Llewyn Elise; Gilden, David Loren, 1954-; Cormack, Lawrence; Kurby, Christopher A.; Maddox, William T.; Markman, ArthurA critical function of perception is the organization of temporally spaced input. This is accomplished through grouping, a process by which within-group elements are integrated with one another to form a cohesive unit. Grouping also requires boundaries to set off within-group elements from unrelated stimuli. In the temporal domain, grouping may be accomplished through use of an implicit working memory system that connects temporally spaced information. Temporal group boundaries may be created by reductions in the default integrative processes of this memory system. The present experiments probed integration strength by embedding priming tasks within temporal groups (i.e., events). Because priming also draws upon implicit working memory, priming strength should reflect the strength of integration. If modulation of temporal integration is responsible for grouping, this should be manifested as a reduction of priming across boundaries. Irrelevant feature priming tasks were used to assess integration strength. Participants responded to one of two independently varying object features. In this form of priming, change consistency of relevant and irrelevant features produces faster reaction times, resulting in a crossed interaction. This interaction served as a meter for the strength of temporal integration. The experiments included a variety of temporal grouping manipulations. Experiments involving rhythmic groups, spatial shifts, rotations, pitch, and timbre, as well as higher-level conceptual shifts, demonstrated reduced priming in across-boundary conditions. Both visual and auditory events were used, and experiments demonstrated that viewers’ interpretation of a scene contributed to the observed effects. Temporal integration does appear to be reduced at certain event boundaries, suggesting that this may be the general manner in which temporal grouping is accomplished. Motion change, a boundary from event segmentation research, did not reduce priming, indicating that the process presently under study differs from that studied using explicit segmentation procedures. The reduction of integration may correspond to a subjective, amodal experience of separation. The present technique may therefore offer an objective, implicit method to assess this sense of separation. Using this method, it is possible to reliably determine when people are experiencing temporal group boundaries even when they are not deliberately attending to them.Item Phonological working memory in adults who do and do not stutter(2011-05) Vallely, Megann Nicole; Byrd, Courtney T.; Sussman, HarveyThe purpose of the present study was to explore whether the phonological encoding difficulties that have been demonstrated in children who stutter persist in adults whose stuttering persists. This hypothesis was investigated by comparing the phonological working memory of adults who stutter (AWS) and adults who do not stutter (AWNS) using non-word repetition and phoneme elision tasks. Twenty-four adults (age range = 17;9 to 46;11 mean age = 28;2): 12 AWS and 12 AWNS matched on gender and age participated in this study. A total of 48 non-words consisting of an equal number (N = 12 per syllable length category) of two-syllable, three-syllable, four-syllable and seven-syllable non-words were selected for use in the non-word repetition and phoneme elision tasks. In the non-word repetition task, results showed a significant interaction between fluency group and syllable length for the 7-syllable length category only, indicating that AWS require a significantly higher mean number of attempts than AWNS. Results of the phoneme elision task revealed a significant main effect for syllable length with both groups demonstrating a significant reduction in accuracy as the non-words increased in length, but there was no significant interaction between fluency group and syllable class length. Potential implications of these findings are presented along with recommendations for future research.Item Phonological working memory in adults who stutter(2018-10-08) Gkalitsiou, Zoi; Byrd, Courtney T.; Griffin, Zenzi M; Marquardt, Thomas P; Sussman, Harvey M; Mahometa, Michael JPhonological working memory has been suggested as one of the multiple factors that contribute to the onset and persistence of stuttering. However, most studies investigating the link between phonological working memory and stuttering incorporated tasks that required an overt verbal response; thus, speech motor influences could not be excluded. Furthermore, stimulus presentation was restricted to auditory input, with no studies investigating both auditory and visual input modalities with the same experimental paradigm. The purpose of this dissertation was to investigate phonological working memory in adults who do and do not stutter using the N-back task as use of this task allowed both visual and auditory stimulus presentation without requiring an overt verbal response. In this task, participants were asked to monitor a series of visual (i.e., images) or auditory (i.e., words) stimuli and respond by pressing a “yes” button if the stimulus they previously viewed or heard was the same as the stimulus 1-, 2-, or 3-trials back. In addition to input modality, the type of linguistic information was also manipulated (i.e., phonologically similar versus dissimilar stimuli). Results indicated that participants performed differently in the visual and the auditory input modality, with AWS demonstrating poorer performance when processing linguistic information auditorily but not visually, for both phonologically similar and dissimilar stimuli.Item Verbal learning ability after traumatic brain injury : roles of working memory and processing speed(2011-08) Ridley, Kristen Paige; Keith, Timothy, 1952-; Allen, Greg; Mercer, Walt; Robillard, Rachel; Schallert, DianeLearning and memory impairments are among the most common and enduring cognitive consequences of traumatic brain injury (TBI). Researchers have yet to reach a consensus with regard to the basic cognitive mechanism underlying new learning and memory disturbances after TBI. The purpose of the present study was to investigate the current views regarding the cognitive processes thought to explain impairments in verbal learning and memory subsequent to brain injury. Specifically, this study sought to examine the roles of the central executive component of working memory and processing speed in verbal learning ability following TBI. Latent variable structural equation modeling (SEM) was used to analyze the data of 70 post-acute care TBI patients between the ages of 16 and 65, who completed a full neuropsychological evaluation. Results indicated that verbal learning and memory difficulties following TBI were explained primarily in terms of the central executive aspects of working memory, after accounting for the relative contributions of processing speed in the model. The direct effect of processing speed on verbal learning and memory was not significant when working memory was taken into account in the model. Rather, the effects of processing speed on verbal learning ability were largely indirect through the central executive component of working memory. Results highlight the importance of both working memory and processing speed in supporting verbal learning and memory processes after TBI. Practical implications for targeting remediation efforts and directing approaches to memory rehabilitation are discussed in light of the study’s findings.Item Working memory and speech production in a 5-year-old child with cochlear implants : a case study(2007-05) Gonzalez, April Rose, 1981-; Davis, Barbara L. (Barbara Lockett)This case study describes the speech production and working memory performance of H, a prelingually deaf female who received her first cochlear implant at 11 months of age, and her second at 2 years of age. Her speech and memory were tested at one time point. H's chronological age at the time of testing was 5 years, 3 months. Data obtained from this study are discussed within the context of the literature that describes speech development and working memory capacities in typically developing and implanted children. Included is a review of speech production, speech perception and working memory processes in both children with normal hearing and children with cochlear implants. Results of analyses indicate that H demonstrated speech production patterns consistent with children with normal hearing. However, a disassociation between speech production performance and working memory capacity was found.