In this paper, binaural beats were used as stimuli to induce Gamma neural activity in the brains of 18 participants with the purpose to see if the effect enhanced memory and/or speech perception. Participants conducted a word-list recall task, followed by a speech-in-noise task under three conditions: before Gamma stimulus, after Gamma stimulus, and after a placebo stimulus. The results showed that the method works to boost Gamma neural activity, but that neither memory nor speech-perception was significantly affected by the stimulus. The conclusion is that binaural beats is unreliable as a method to enhance memory and speech-perception in humans.

Working memory is a mental workspace which utilizes short and long-term memory to maintain and manipulate information. It is crucial in enabling cognitive control and is largely controlled by interactions within and between frontal and parietal cortices. Recent work has identified visual nonspatial, spatial, and visuospatial working memory spectral characteristics of the local field potential through simultaneous recordings from various areas across the monkey frontoparietal network. However, the reports are minimal in number, and there is no clear narrative tying together the heterogenous functionality of the characteristics. Here, a new spectral model of monkey visual working memory is proposed to address these shortcomings. It highlights functional roles for low, mid, and high frequency bands. Next, the organization of structural connectivity which gives rise to these spectral characteristics is investigated. A new binary association matrix representing connections in the frontoparietal network is proposed. A graph theoretic analysis on the matrix found that a 3-node dynamical relaying M9 motif was a fundamental building block of the network. It is optimally structured for the synchrony found in the spectral model. The network was also found to have a small-world architecture, which confers the integration and specialization of function required by visual working memory. Afterwards, three hypotheses generated by the spectral model are tested on non-spatial data. The low and mid band hypotheses were supported by evidence, while the high band hypothesized activity was not observed. This adds credibility to the roles identified in the model for the low and mid band and identifies a need for further investigation of the high band role. Finally, opportunities to expand the spectral model, analyze the M9 motif, and further test the model are explored. In the future, the spectral model could evolve to apply its predictions to humans in the pursuit of treatments for neurological disorders. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Working memory (WM) is a crucial component of cognitive function that affects learning, reasoning, and problem solving, all of which are important for daily functioning. Therefore, addressing factors that can impact working memory, such as stress, are incredibly relevant to understanding WM efficiency. WM is an important component of higher order cognitive function and high WM capacity has been shown to be important for academic and occupational performance. Thus, understanding the relationship between stress-related factors and WM could aid in identifying strategies to mitigate the deleterious effects of stress on working memory. Although some previous research has indicated a negative impact of acute stress on WM, other research has indicated no impact or even a positive impact of stress on WM. As the relationship between acute stress and WM is mixed, examining other stress-related factors may provide further insight into the relationship. The current study examines how adverse childhood experiences (ACEs) and acute stress influence WM, and how frontal theta and alpha activity are affected by WM task demands. Participants completed a working memory task while their EEG was recorded. Participants then completed the PANAS to assess their current emotional state. Following the PANAS, participants viewed a stressful or neutral video as an acute stress induction, followed by a second PANAS to ensure effectiveness of stress induction. Participants then completed the WM task a second time. Finally, the participants completed the ACEs questionnaire. Bayesian linear mixed effects models were used to examine the relationships between ACEs, acute stress, WM, and frontal theta and alpha frequencies. Findings suggest there is not enough evidence to support a relationship between acute stress, ACEs, WM, and WM-related theta and alpha. While the current study did not reveal a relationship, future research should explore how acute stress and exposure to specific stressors during childhood could explain individual differences in WM.

Indiana University-Purdue University Indianapolis (IUPUI) / Posttraumatic stress disorder involves a constellation of neural and behavioral alterations in response to trauma exposure. Aside from symptoms involved in posttraumatic stress disorder diagnosis, patients frequently present with working memory impairments. Working memory training has been established as an effective intervention to reduce posttraumatic stress symptoms. Working memory is associated with posttraumatic stress disorder in that it is commonly impaired in patients and that training can reduce the severity of posttraumatic stress symptoms. Taken together, these points suggest the possibility of a shared mechanism between working memory and posttraumatic stress disorder but working memory has not been studied thoroughly in rodent models of posttraumatic stress disorder. The present study utilizes footshock trauma to induce a posttraumatic stress state in rats and evaluates the effect of trauma and trauma-paired cues on working memory performance. Results demonstrate the emergence of chronic deficits in working memory among traumatized animals three weeks post-trauma. Presentation of trauma-paired cues caused further decrement in working memory performance. Regression analysis indicates that the degree of working memory impairment in response to a trauma-paired cue can be significantly predicted by behavioral phenotypes typic of diagnostic symptoms for posttraumatic stress disorder. This study enhances existing animal models by replicating the clinical observations of working memory deficits associated with posttraumatic stress disorder. This will pave the way for future work to probe underlying mechanistic dysregulation of working memory following trauma exposure and for future development of novel treatment strategies.

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Šárka Timarová: Pracovní paměť v konferenčním simultánním tlumočení disertační práce Abstrakt Tato disertační práce se zaměřuje na otázku zapojení pracovní paměti v procesu konferenčního tlumočení. Pracovní paměť je pro simultánní tlumočení považována za klíčový kognitivní mechanismus, ale toto tvrzení zatím nebylo významně empiricky podloženo. Předkládaná studie vychází z teoretické literatury jak v oblasti tlumočení, tak v oblasti kognitivní psychologie. Analýza publikovaných empirických prací ukázala několik mezer v současném bádání, a to především skutečnost, že výzkum se dosud soustředil pouze na některé funkce pracovní paměti (především funkce paměťové) a na testování osob bez tlumočnické praxe či s praxí omezenou (studenti tlumočení). Předkládaná studie pojímá pracovní paměť šířeji se zvláštním zřetelem k funkcím řídícím, které úzce souvisejí s pozorností, a dále se zaměřuje výlučně na profesionální tlumočníky. Podstatou studie je srovnání výkonu tlumočníků v testech pracovní paměti a při simultánním tlumočení. Výsledky ukazují, že a) existuje vztah mezi pracovní pamětí tlumočníků a simultánním tlumočením, b) tento vztah se týká především funkcí řídících; u funkcí paměťových se žádný zásadní vztah neprokázal, c) některé funkce pracovní paměti se rozvíjejí spolu s tlumočnickou praxí, a d) vztah...

The ability to attentively filter sensory information and manipulate it in working memory is critical for our ability to interact with the world. Although primary and secondary sensory cortical areas have been well-studied, frontal lobe contributions to sensory attention and working memory remain under-investigated. This dissertation investigates the topography and network organization of sensory-biased and multi-sensory regions in the healthy human brain using functional magnetic resonance imaging (fMRI). First, this research developed a series of functional connectivity analyses of data from the Human Connectome Project to validate and extend recently localized auditory-biased network structures, transverse gyrus intersecting the precentral sulcus (tgPCS) and caudal inferior frontal sulcus (cIFS), and visual-biased network structures, superior precentral sulcus (sPCS) and inferior precentral sulcus (iPCS), in lateral frontal cortex (LFC). Results replicated the original findings and extended them by revealing five additional bilateral LFC regions, including middle inferior frontal sulcus (midIFS) and frontal operculum (FO), differentially connected to either the visual- or auditory-biased networks. Due to inter-subject anatomical variability, identification of sPCS, tgPCS, iPCS and cIFS depends critically on within-subject analyses. Next, this work demonstrated that an individual’s unique pattern of resting-state functional connectivity can accurately identify their specific pattern of working memory (WM) and attention task activation in LFC using “connectome fingerprinting” (CF). CF predictions were superior to group-average predictions and matched the accuracy of within-subject task-based functional localization. This research developed and validated methods that use intrinsic functional connectivity information to perform functional brain analyses on highly idiosyncratic brain regions. Finally, a combined auditory, tactile and visual WM study revealed the joint organization of sensory-biased and multi-sensory regions within individual subjects. Hypothesized visual-biased midIFS and auditory-biased FO regions were functionally confirmed for the first time. Several bilateral tactile-biased regions, premotor dorsal, premotor ventral, anterior middle frontal gyrus, middle insula, postcentral sulcus, posterior middle temporal gyrus and pre-supplemental motor area, abutting previously described visual- and auditory-biased regions were identified. Several multi-sensory WM regions, recruited in each stimulus modality, were observed to partially overlap with visual-biased regions. Intrinsic functional connectivity analyses revealed that regions segregate into networks largely based upon their modality preferences. / 2020-06-14T00:00:00Z

Neural oscillations, including rhythms in the beta1 band (12-20 Hz), are important in various cognitive functions. Often brain networks receive rhythmic input at frequencies different than their natural frequency, so understanding how neural networks process rhythmic input is important for understanding their function in the brain. In the current thesis we study a beta1 rhythm that appears in the parietal cortex, focusing on the way it interacts with other incoming rhythms, and the implications of this interaction for cognition. The main part of the thesis consists of two stand-alone chapters, both using as a basis a biophysical neural network model that has been previously proposed to model the parietal beta1 rhythm and validated with in vitro experiments. In the first chapter we use a reduced version of this model, in order to study its dynamics, applying both analytic and numerical methods from dynamical systems. We show that a cell can respond at the same time to two periodic stimuli of unrelated frequencies, firing in phase with one, but with a mean firing rate equal to the other, a consequence of general properties of the dynamics of the network. We next show numerically that the behavior of a different cell, which is modeled as a high-dimensional dynamical system, can be described in a surprisingly simple way, owing to a reset that occurs in the state space when the cell fires. The interaction of the two cells leads to novel combinations of properties for neural dynamics, such as mode-locking to an input without phase-locking to it. In the second chapter, we study the ability of the beta1 model to support memory functions, in particular working memory. Working memory is a highly distributed component of the brain's memory systems, partially based in the parietal cortex. We show numerically that the parietal beta1 rhythm can provide an anatomical substrate for an episodic buffer of working memory. Specifically, it can support flexible and updatable representations of sensory input which are sensitive to distractors, allow for a read-out mechanism, and can be modulated or terminated by executive input.

During decision-making, an individual must weigh the value of the outcomes involved while also considering the amount of time until the outcomes will occur. Discounting occurs when a smaller, immediately available reward is chosen over a larger, more delayed reward. Discounting rates are likely related to working memory capacity, because working memory stores and processes the value of the outcomes. The purpose of this study was to examine the relationship between working memory, temporal discounting, and the decision to engage in physical activity. The results showed that working memory capacity was related to the physical activity rates. Discounting rates from a money task and a health task were not related to activity rates. However, in the subsample of individuals who reported that their primary motive to exercise was health, working memory and discounting rates from the money task were both statistically significant predictors of physical activity.

Indiana University-Purdue University Indianapolis (IUPUI) / In accord with the cognitive model of poor functioning in schizophrenia, defeatist performance beliefs, or overgeneralized negative beliefs about one’s ability to perform tasks, have been linked to poor functional outcomes, cognitive impairment, and negative symptoms in schizophrenia and are a suggested therapeutic target in Cognitive Therapy for Schizophrenia. However, there is a paucity of research investigating these beliefs in schizotypy, or those exhibiting traits reflecting a putative genetic liability for schizophrenia. This study had three aims: to examine whether defeatist performance beliefs 1) are elevated in schizotypy compared to non-schizotypy, 2) are associated with functioning-related outcomes (i.e., quality of life, working memory, negative schizotypy traits), and 3) mediate the relationships between working memory and both negative schizotypy traits and quality of life. Schizotypy (n = 43) and non-schizotypy (n = 45) groups completed measures of schizotypy traits, defeatist performance beliefs, quality of life, and working memory. Results revealed that the schizotypy group reported significantly more defeatist performance beliefs than the non-schizotypy group. Within the schizotypy group, defeatist performance beliefs were significantly positively associated with negative schizotypy traits and significantly inversely associated with quality of life. No associations were observed between defeatist performance beliefs and positive schizotypy traits and working memory. Further, defeatist performance beliefs did not mediate the relationships between working memory and either quality of life or negative schizotypy traits. Findings are generally consistent with the cognitive model of poor functioning in schizophrenia and suggest that defeatist performance beliefs may be an important therapeutic target in early intervention services.