Browsing by Author "Tamber-Rosenau, Benjamin J."
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Item An Exploration of Variability Due to Low Power in Structural MRI Studies of Bilingualism(2018-12) Munson, Brandin A.; Hernandez, Arturo E.; Francis, David J.; Tamber-Rosenau, Benjamin J.; Chiarello, ChristineThe adequacy of replicability among psychological findings has previously been questioned, especially for neuroscientific fields of research. Researchers increasingly point towards the negative effects of low power on replicability of findings. Though decreased sensitivity in smaller samples is a well-known consequence of inadequate power, many overlook the increased likelihood of inflated observed effects and weakened positive predictive values. The aim of this study is to reveal the expected degrees of uncertainty among neuroimaging findings by conducting tests in different sample sizes from a larger-than-average sample, in an area of research with wide-ranging findings that have been proposed by some to be due in part to inadequate sample sizes: bilingual-monolingual structural brain differences. Bilinguals (n = 216) were compared with monolinguals (n = 146) using grey matter density in whole-brain analyses and grey matter volume measures across region-of-interest tests. Variability among findings were compared with the true full-sample findings, and taken in the context of expected differences within the larger bilingualism neuroimaging literature. Results demonstrate excessive variability across the lowest sample sizes (e.g. samples totaling 20 – 80 participants), and this is explored through the trends of subsample outcomes and effect sizes across sample sizes. The extent to which infrequently utilized methods such as multivariate analyses of covariance (MANCOVAs) and Bayes Factors can improve the accuracy of results at lower sample sizes were also explored. It is our hope that this study helps to demonstrate the influences of power on expected variability among sample findings, especially for bilingual researchers and any researchers interested in exploring group differences using neuroimaging.Item Bilingual language control: Bottom-up versus top-down(2021-05) Bodet, Tres P.; Hernandez, Arturo E.; Tamber-Rosenau, Benjamin J.; Leasure, J. LeighBilinguals’ language control mechanisms are well-researched and modelled. An overlooked aspect of their environment, however, is the language context. This research study asks whether context (bottom-up influence) may impact effortful language control mechanisms (top-down control). The present research tests the hypothesis that context can affect top-down language control, and that the extent of these effects are context-dependent, by manipulating auditory language distractors in a picture-naming paradigm with no cued language-switching. This was a departure from the norm of cueing a bilingual to switch languages in order to evidence a proposed language control mechanism. In short, participants heard brief, trial-length audio distractors while engaged in English-only picture-naming. The distractor languages varied per block and were Hungarian, English, Spanish, and Mixed (English and Spanish distractor trials randomly dispersed throughout the block). By removing any cued language-switching (topdown switching) and only changing the context (using auditory distractors), the results yielded can be attributed to the impact of changing bottom-up influence. In the end, the results did not support the hypotheses presented—image-naming response times did not differ significantly between contexts. However, results may suggest that while the immediate effects of a change in context are consistent, the lasting effects may differ from context to context. A number of measures of individual differences significantly influenced these results as well, including cognitive control abilities and English proficiency. While these results do support the view that context matters, future studies are needed to better elucidate the way in which it does or does not matter.Item Brain Structure and Age of Acquisition in Bilinguals and Monolinguals(2018-12) Claussenius-Kalman, Hannah; Hernandez, Arturo E.; Leasure, J. Leigh; Tamber-Rosenau, Benjamin J.Researchers debate whether the age of second language acquisition (AoA) plays any role in determining brain structure. Whereas some studies suggest that bilinguals handle both languages via a single set of cognitive control regions regardless of AoA, others suggest that each language depends on different sets of brain regions for late (but not early/simultaneous) bilinguals. Likewise, structural neuroimaging studies have come to contrasting conclusions: either AoA does not affect structure, or later AoA relates to gray matter expansion in cognitive control and language processing regions. These differing results may occur for two main reasons: 1) low power caused by small group sizes, and 2) a lack of consistency in measures (of brain structure and of AoA) used across studies. This study aimed to address both of these gaps. MRI scans were used to measure cortical thickness, volume, and density via whole-brain analyses of 216 bilingual and 145 monolingual human adults (male and female). Results showed that the neuroanatomical correlates of AoA differ in terms of cortical thickness, volume, and density. Specifically: 1) late bilinguals had thicker cortex than monolinguals, simultaneous bilinguals, and early bilinguals in left and right frontal, temporal, parietal, and occipital regions; 2) no volume differences were found, and 3) compared to monolinguals, late bilinguals had greater density in the left middle frontal gyrus and right pars opercularis and postcentral gyrus, whereas early bilinguals had greater density in the bilateral temporal pole, right middle frontal gyrus, and right postcentral gyrus. The one similar finding across all brain structure measures was that monolinguals and simultaneous bilinguals did not differ. Results suggest that, relative to simultaneous bilinguals and monolinguals, late bilinguals handle language via structural increases in language processing and cognitive control areas. The present results demonstrate that it is important to use multiple measures of brain structure in order to clarify our understanding of bilingual language acquisition, as well as the importance of obtaining sufficient power to test hypotheses using whole-brain analyses.Item Comparing the Time Courses of Top-Down and Bottom-Up Attention in the Temporal Domain(2019-12) Swami, ApurvaAttention shifts within and between time and space frequently during our everyday life. Attention can be controlled both voluntarily and involuntarily and the brain must choose which stimuli are most relevant to process. It is known that this shift in attentional control is costly for the brain in terms of time and resources. In comparison to the well-studied spatial attention, the time courses of top-down (voluntary) and bottom-up (involuntary) temporal attention are less well-known. We examined both top-down and bottom-up attention using the attentional blink and emotion-induced blindness paradigms respectively in order to better understand whether the hallmarks of top-down/bottom-up distinctions in spatial attentional control also occur in temporal attentional control. Participants searched rapid serial visual presentation streams for either two targets or one target following an emotional distractor image. The results showed that participants demonstrated an AB effect, but most likely failed to notice the emotional distractor images and therefore did not show an EIB effect. Due to the lack of the AB-like effect in the EIB condition, this study remains inconclusive as the data in the bottom-up attentional control (EIB) condition were not interpretable.Item Exploring the Limits of the Emotional Attentional Blink(2023-05-22) Santacroce, Lindsay Ashton; Tamber-Rosenau, Benjamin J.; Hernandez, Arturo E.; Bick, Johanna R.; Leonard, Carly J.In the emotional attentional blink (EAB; also termed emotion-induced blindness), a single target in a rapid serial visual presentation (RSVP) stream of fillers is difficult to report when it is preceded by a task-irrelevant emotional distractor, indicating temporal attentional capture by emotion. However, recent research has shown that the EAB is weaker than previously assumed and has suggested that emotion is not a strong driver of stimulus-driven attentional capture, at least in RSVP tasks. This dissertation explored the limits of the EAB with two aims: Aim 1 asked if the EAB is actually driven by emotion, or rather visual distinctiveness that is then modulated by emotion. Using RSVP streams with critical distractors that were emotional, visually distinct, both, or neither, the results support the latter account, and further suggest that the EAB can be characterized as two phases. In Experiment 1.1 with image stimuli, visual salience (regardless of emotion) led to an immediate—but rapidly attenuating—blink, while emotion with low visual salience led to a delayed blink with sparing of early lags. Experiment 1.2 with word stimuli did not show this same effect. Aim 2 asked if emotion appears to be a weak driver of stimulus-driven attentional capture in the EAB because the rapid dynamics of RSVP tasks require general suppression of all stimulus-driven attention to enhance goal-driven attentional control. The two experiments for Aim 2 (Experiment 2.1 with images and 2.2 with words) utilized a novel “skeletal” EAB paradigm with most filler items removed (as previously used in some two-target attentional blink studies) and compared performance to the typical EAB paradigm. Contrary to predictions, similar EABs were observed in skeletal and RSVP paradigms, suggesting that general suppression of all items in RSVP streams does not lead to a weaker EAB. Together, these aims provide a better understanding of the EAB and stimulus-driven attentional capture by emotional stimuli.Item Investigating Gaze Orientation and Spatial Localization in Strabismus(2023-05-15) Karsolia, Apoorva; Das, Vallabh E.; Stevenson, Scott B.; Nurminen, Lauri; Tamber-Rosenau, Benjamin J.Purpose: Disruption of binocular vision during the critical period of development results in strabismus in 3-5% of the population. The visual system adapts to this decorrelation with the help of suppressive mechanisms that influence eye choice behavior. The overall goal of this research was to identify visual and non-visual factors that may impact gaze orientation and localization behavior in strabismus. These studies shed light on the mechanisms underlying binocular vision and spatial localization and provide insights into the temporal dynamics of visual suppression and its impact on eye-choice behavior. Methods: In Aim 1, development of horizontal and vertical ocular alignment was assessed in six prism-reared infant monkeys using Hirschberg photographic methods. In Aim 2, ten human subjects with normal ocular alignment localized briefly presented targets, presented to same or alternate eyes under dichoptic conditions, in an unreferenced environment. In Aim 3, eye movements were recorded in two adult exotropic monkeys while performing memory saccade tasks with variable delays to assess influence on persistence of visual information on fixation-preference. Results: Aim 1: Monkeys reared with prisms during infancy developed strabismus as early as 3 weeks of age (~3 months in humans) suggesting influence of both visual and non-visual mechanisms in development of normal alignment. Aim 2: Under conditions of binocular competition (dichoptic viewing), human subjects were unable to compensate for their inherent phoria and made greater errors as compared to same-eye viewing condition. Aim 3: Fixation preference behavior was observed in adult prism-reared monkeys during memory-guided saccades, similar to patterns observed during visually-guided saccades. Memory delays up to 800msec did not alter fixation preference behavior. Conclusion: Prism-reared monkeys mimic strabismus in humans and are a useful model to study its behavioral and neurophysiological implications including influence of oculomotor proprioception. Binocular dissociation in absence of visual cues, leads to inaccurate localization even in normal ocular alignment, indicating that extra-retinal eye position feedback in the form of oculomotor proprioception may be imprecise or derived from the wrong eye. Visual suppression in strabismus leads to long-lasting adaptations that influence eye choice behavior beyond the stimulus presentation time (800ms), as indicated by fixation patterns of localization.Item Language Dimensionality and the Contribution of Cognitive Abilities on Verbal Repetition Tasks Performance in Spanish-English Bilingual Children with and without Developmental Language Disorders(2022-08-19) Ronderos, Juliana; Hernandez, Arturo E.; Castilla-Earls, Anny; Yoshida, Hanako; Tamber-Rosenau, Benjamin J.; Fitton, LisaPurpose: In the first study, we explored the dimensionality of language abilities in bilingual children using measures of vocabulary and morphosyntax in English and Spanish used clinically to identify bilingual children with DLD. In the second study, we look at selected cognitive processing skills to better understand their unique contribution to performance in verbal repetition tasks (sentence repetition and nonword repetition), which are frequently part of standardized language assessments for the diagnosis of DLD. Method: Participants included 112 Spanish-English bilingual children ages 4-8 from a wide range of language abilities and language dominance profiles. Participants completed a battery of cognitive assessments and language assessments in Spanish and English. The cognitive session included general measures of cognitive abilities (nonverbal IQ and processing speed), short-term memory and working memory, cognitive flexibility, and inhibitory/attentional control. The language sessions included measures of vocabulary and morphosyntax from both norm-referenced assessments and language samples. Results: In the first study, the model which best fit the data was a model with two correlated factors, one for Spanish and one for English. This model used a subset of the observed measures from norm-referenced assessments and language samples representing vocabulary and morphosyntax in both languages. In the second study, results indicate that the strongest predictors for SR task are measures of language abilities and then measures of short-term memory. For NWR, the strongest predictors are measures of short-term memory and then measures of language ability. Conclusions: These results indicate that the structure of language in bilinguals is different from that previously found in English monolingual children of similar ages. In contrast to the unidimensional structure found for English monolingual children, language in Spanish-English children seems to represent two related but distinct constructs that may be influenced differently by language ability and language experience. Our results for the second study suggest that the verbal repetition tasks have similar underlying mechanisms. Although the skills to reproduce sentences and nonwords may overlap, it is understood that sentence repetition requires more linguistic knowledge than nonword repetition to reproduce the complete syntactic structure required. Clarifying how language in bilinguals is conceptualized and impacted by the concurrent development of two languages is an area that requires further research. Understanding both the dimensionality of language in bilinguals and the contribution of cognitive processing skills to language abilities can further assist our knowledge of how language develops in bilingual children and how it is affected by internal cognitive abilities.Item Mechanisms of Sensory Integration During Postural Adaptation(2020-05) Young, David R.; Layne, Charles S.; Parikh, Pranav J.; Lee, Beom-Chan; Tamber-Rosenau, Benjamin J.The body schema is an internal representation of the position of one’s body in relationship to the environment. Adaptation of the body schema involves an update of this internal model in response to changes in the task or the environment. Plasticity of the body schema during postural control allows for one to adapt to changes or hazards in their environment. The level of plasticity is related to the efficiency of integration of sensory feedback in the cortex. This investigation sought to improve the understanding of postural adaptation by identifying the impact of sensory reweighting during a postural adaptation task. Additionally, this investigation sought to identify the effects of bilateral neuromodulation of the posterior parietal cortex (PPC) using transcranial direct current stimulation (tDCS) on postural adaptation. We proposed three experiments to accomplish these goals. During the first experiment, we presented tendon vibration during an incline-intervention, which results an adaptation consisting of an anterior shift in position known as lean after-effect (LAE). During the second experiment, we presented tendon vibration after an incline-intervention. During the third experiment, we performed tDCS prior to an incline-intervention. Primary analyses of the data collected during this investigation revealed that an inclined support surface altered subjects’ response to vibration. We also found that vibration during an inclined stance did not alter the development of LAE, but vibration during the after-effect period had direction specific effects. Last, we found that neuromodulation of the PPC led to alterations in LAE. Results of this dissertation identified effects of proprioceptive reliability on the development of postural adaptation induced by an incline-intervention. Furthermore, this dissertation identified the direction specific results of altered support surface inclination on the effects of tendon vibration, providing new insights to this line of research. Results also help to improve the understanding of the role of the PPC in postural adaptation associated with adaptation of the body schema. These insights may lead to improvements in understanding of the role of the body schema in postural control, which may lead to improvements in strategies for the maintenance and rehabilitation of postural control in aging and disabled populations.Item Neural Mechanisms Underlying Literacy in Bilingual Children with Typical and Atypical Reading Development(2021-12) Claussenius-Kalman, Hannah; Hernandez, Arturo E.; Tamber-Rosenau, Benjamin J.; Fletcher, Jack M.; Church-Lang, JessicaOne in five children in the United States is bilingual. Despite a plethora of research on monolingual reading development, it is unclear how the brain develops to support literacy when two languages are being learned. Furthermore, it is poorly understood how these neural processes develop in bilingual children who are at risk of having reading difficulties. This study aimed to identify the neural correlates of literacy in 69 bilingual middle schoolers with English reading skills above and below state of Texas benchmarks. Children were given a language questionnaire, proficiency assessments, and were asked to complete reading-related tasks while in a magnetic resonance imaging (MRI) scanner that collected functional brain data. Some evidence was found for Hypothesis 1, which was that better task performance would predict ventral reading route activation and worse performance would predict dorsal activation. Specifically, whole-brain general linear modelling showed a positive relationship between task performance and left occipitotemporal activity (part of the ventral route). On the other hand, there was an inverse relationship between task performance and two non-hypothesized areas (right angular gyrus and secondary visual area). These findings indicate that, for bilingual children, recruitment of right hemisphere regions may help compensate when orthographic processing in the second language is less (or not yet) automatized. Hypothesis 2, which was that English proficiency would mediate the relationship between task performance and task activation, was rejected. Instead, post hoc analyses showed that self-report, but not objective, proficiency predicted brain activation in motor and visual regions. These findings highlight the notion that self-report proficiency can capture certain components of language skill that objective measures do not.Item NEUROBEHAVIORAL CORRELATES OF EMBODIMENT IN IMMERSIVE VIRTUAL-REALITY-ASSISTED LEARNING(2023-12) Bodet, Tres; Hernandez, Arturo E.; Pollonini, Luca; Tamber-Rosenau, Benjamin J.; Robinson, Jennifer L.This project aims to investigate the effect of embodiment in immersive virtual reality (iVR) learning. Implementing iVR in the classroom is an opportunity to increase student engagement, and researchers suspect that iVR’s potential for sensorimotor engagement in learning (i.e., embodiment) is a means of improving learning outcomes. Embodiment in the real world consistently improves learning outcomes, but research has not always supported this same relationship in iVR learning. Thus, it is not clear whether embodiment plays a role in iVR-assisted learning. To investigate this, I recorded learning outcomes (short-term and long-term) and neural activity in scenarios of low, medium, and high embodiment word-learning in iVR. I used neural activity to glean deeper insight into embodiment’s seemingly complex relationship with behavioral iVR learning outcomes. Results, similar to past research, show that embodiment had a negative effect overall. However, increasing embodiment may have increasingly protected learned words from long-term decay. Neural data suggest that the L-AG played a significant role in processing related to long-term learning outcomes, suggesting it may underlie the observed protective effects of embodiment. Results led me to suggest that intertwined effects of novelty, distraction, and decreased sense of presence were drivers of embodiment’s short-term negative effects, and research shows that more effective implementation of iVR learning should negate these issues. Based on these neurobehavioral data, it seems embodiment has a negative effect on short-term iVR-assisted learning outcomes and a protective effect on successfully-learned information over time.Item Non-Target Emotional Stimuli Must Be Highly Conspicuous in Order to Break through the Attentional Blink(2019-12) Santacroce, Lindsay Ashton; Tamber-Rosenau, Benjamin J.; Hernandez, Arturo E.; Bick, Johanna R.In the attentional blink (AB), the second of two targets (T2) separated by a short lag in a rapid serial visual presentation (RSVP) stream is difficult to report. The AB is typically thought of as a top-down effect because it is triggered when the first target (T1) matches a search template. However, the AB is modulated when either target has emotional valence, and an AB-like effect can be triggered when a task-irrelevant but valenced critical distractor item (CDI) replaces T1. Neither target nor CDI valence manipulations fully captures the interplay between bottom-up and top-down attention in the AB. The valenced-target approach intrinsically conflates top-down and bottom-up attention. The CDI approach does not manipulate final-target valence, which is critical because such a manipulation can cause a target to “break through” the AB (in the target-manipulation approach). The novel approach of the present research resolves this methodological challenge by indirectly measuring whether a purely bottom-up CDI can break through the AB. This is accomplished by adding a valenced CDI to the “classic,” two-target AB. Participants viewed RSVP streams containing a T1-CDI pair followed by a variable lag and then T2. If the CDI’s emotional valence is sufficient to break through the AB, T2 performance should be modulated by CDI valence, yielding an indirect signal of bottom-up capture by emotional stimuli. Results demonstrated that CDI valence only affects the AB when CDIs are also extremely visually conspicuous. Thus, emotional valence alone is insufficient to break through the AB.Item Relationship Between Cognitive-Cognitive and Cognitive-Motor Dual-Task Interference(2017-10-12) Kumar, AkshatCognitive (cog) tasks require mental effort. Motor (mot) tasks require physical movement. Dual-task (DT) interference is the slower or less accurate performance of two tasks performed simultaneously compared to when each is performed individually. Cog-cog DT and cog-mot DT interference have both been studied individually but it is unknown if they stem from the same capacity limit in the brain. Cog-mot DT interference has been linked to increased fall risk and the development of neurological disorders.1 Linking cog-mot DT interference to cog-cog DT interference could provide new, safer methods of diagnosis/prognosis. Conclusions. Participants who had less cog-cog DT costs tended to have the most DT interference while walking. DT interference in the cog-cog domain may be predictive of DT interference in the cog-mot domain as many of the correlations trended towards significance.Item Searching for Gait Markers of Cognitive-Motor Dual-task Interference using Machine Learning(2021-04-01) Oak, AnushkaPerforming two concurrent tasks, or dual-tasking (DT), commonly results in reduced performance especially when compared to single tasking (ST). Two kinds of DT have been studied in largely separate literatures: concurrent cognitive tasks (cognitive-cognitive: CC) and concurrent cognitive task and motor tasks (cognitive-motor: CM). The present project’s long-term goal is to serve as a proof-of-principal for future studies to relate CC and CM DT in at-risk populations for high DT costs and consequences (e.g. falls in the elderly). The project’s immediate goal is to develop a more sensitive measure for CM DT. Healthy young adult participants (N=9) walked at a set pace, performed a demanding cognitive task (serial sevens subtraction), or performed both tasks concurrently. Motor behavior was tracked using a pressure-sensitive treadmill and 3D motion tracking. These data were reconstructed using Vicon Nexus software and custom preprocessing with MATLAB, iteratively divided into training/testing sets, and submitted to a linear support vector machine learning classifier. All classification was performed within participants. Though a t-test did not result in statistical significance for the group, more sensitive within-participant permutation tests revealed significant above-chance classification in 7 of 9 participants. This result indicates that 3D motion parameters can support detection of CM DT from gait at a constant walking speed. Future analyses will include refined preprocessing, alternative machine learning approaches, and classification based on higher-order features of the data. Support vector machine feature weights will also be analyzed to identify informative/uninformative features, potentially allowing streamlining of future data collection.Item The Role of the DLPFC in Bilingual and Monolingual Switching: Evidence from MVPA and tDCS(2018-12) Vaughn, Kelly; Hernandez, Arturo E.; Tamber-Rosenau, Benjamin J.; Leasure, J. Leigh; Pollonini, LucaPrevious research suggests that the bilingual experience controlling two languages may transfer to non-linguistic control tasks, resulting in a “bilingual advantage.” If this is the case, there should be a neural basis for this transfer (i.e., a region of the brain involved in both types of control). The dorsolateral prefrontal cortex (DLPFC) is one candidate brain region involved in these two types of control. The current studies had two aims. The first was to determine whether bilingual language control and non-linguistic control relate similarly to the DLPFC, and the second was to determine whether bilinguals and monolinguals differed in this relationship. The first study used multi-voxel pattern analysis (MVPA) to determine whether the patterns of fMRI activity in the left and right DLPFC for language control were similar to the patterns of activity for non-linguistic control. In this study, the left DLPFC showed predictable patterns of activity for non-linguistic control in both bilinguals and monolinguals, but no predictable patterns of activity for language control. The second study used transcranial direct current stimulation (tDCS) to directly alter the functioning of the left or right DLPFC for language control and non-linguistic control. In this study, left DLPFC stimulation hurt bilingual performance on the non-linguistic control task, but helped overall performance on the bilingual language control task. These findings suggest that the bilingual DLPFC is involved in language control, but not in a way that benefits non-linguistic control. If a “bilingual advantage” exists, it is important that researchers continue to explore which regions of the brain facilitate the transfer from language control to non-linguistic control.Item The Slow Rate of Visual Working Memory Consolidation Is a Structural Limit(2020-05) Carlos, Brandon John; Tamber-Rosenau, Benjamin J.; Cirino, Paul T.; Yoshida, HanakoExtensive research has focused on the limited storage capacity of working memory (WM), i.e., the maximum amount of information that can be maintained in WM. However, a relatively understudied limitation of WM involves the processing speed by which sensory information can be transformed into a WM representation that is resistant to distraction from ongoing perception and cognition. The speed of this “consolidation” process is the subject of conflicting results. Researchers have arrived at estimates of the consolidation time course using distinct paradigms ranging from 25 ms to 1 s, meaning more than an order of magnitude of variability. The extremely large variation in WM consolidation speed estimates across measurement approaches motivated the current work’s goal of determining whether consolidation speed is under strategic control or is a stable structural constraint of WM encoding. Here, the slower (1 s) measurement of WM consolidation of visually-presented verbal stimuli (i.e., letters) was replicated by using retroactive interference (RI; Nieuwenstein & Wyble, 2014)—essentially, measuring how long it takes after a WM sample array is presented for the representation in WM to no longer be vulnerable to distraction by performing a speeded second task (T2). Then, the RI results were extended to more standard visual WM stimuli (i.e., color patches). Further, slow consolidation was obtained regardless of the relative prioritization of WM encoding vs. T2, supporting the structural account. However, no RI was obtained when T2 was unspeeded. Finally, a sensorimotor decision and motor response to T2 were required to obtain RI. Given that RI was robust to varying WM probes, WM stimuli, and that slow consolidation was obtained regardless of strategic demands, the present study supports the structural account of WM consolidation.