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Title: 1/f structure of temporal fluctuation in rhythm performance and rhythmic coordination.
Creator: Rankin, Summer K., Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description: This dissertation investigated the nature of pulse in the tempo fluctuation of music performance and how people entrain with these performed musical rhythms. In Experiment 1, one skilled pianist performed four compositions with natural tempo fluctuation. The changes in tempo showed long-range correlation and fractal (1/f) scaling for all four performances. To determine whether the finding of 1/f structure would generalize to other pianists, musical styles, and performance practices, fractal...
Show moreThis dissertation investigated the nature of pulse in the tempo fluctuation of music performance and how people entrain with these performed musical rhythms. In Experiment 1, one skilled pianist performed four compositions with natural tempo fluctuation. The changes in tempo showed long-range correlation and fractal (1/f) scaling for all four performances. To determine whether the finding of 1/f structure would generalize to other pianists, musical styles, and performance practices, fractal analyses were conducted on a large database of piano performances in Experiment 3. Analyses revealed signicant long-range serial correlations in 96% of the performances. Analysis showed that the degree of fractal structure depended on piece, suggesting that there is something in the composition's musical structure which causes pianists' tempo fluctuations to have a similar degree of fractal structure. Thus, musical tempo fluctuations exhibit long-range correlations and fractal scaling. To examine how people entrain to these temporal fluctuations, a series of behavioral experiments were conducted where subjects were asked to tap the pulse (beat) to temporally fluctuating stimuli. The stimuli for Experiment 2 were musical performances from Experiment 1, with mechanical versions serving as controls. Subjects entrained to all stimuli at two metrical levels, and predicted the tempo fluctuations observed in Experiment 1. Fractal analyses showed that the fractal structure of the stimuli was reected in the inter-tap intervals, suggesting a possible relationship between fractal tempo scaling, pulse perception, and entrainment. Experiments 4-7 investigated the extent to which people use long-range correlation and fractal scaling to predict tempo fluctuations in fluctuating rhythmic sequences., Both natural and synthetic long-range correlations enabled prediction, as well as shuffled versions which contained no long-term fluctuations. Fractal structure of the stimuli was again in the inter-tap intervals, with persistence for the fractal stimuli, and antipersistence for the shuffled stimuli. 1/f temporal structure is suficient though not necessary for prediction of fluctuations in a stimulus with large temporal fluctuations.
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Date Issued: 2010
PURL: http://purl.flvc.org/FAU/2705083
Subject Headings: Music, Psychological aspects, Emotions in music, Perceptual-motor learning, Computational neuroscience, Synchronization, Musical perception
Format: Document (PDF)

Title: 2009-2010 Program Review Complex Systems.
Creator: Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2009-2010
PURL: http://purl.flvc.org/fau/fd/FA00007674
Format: Document (PDF)

Title: 2010-2011 Program Review Complex Systems.
Creator: Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2010-2011
PURL: http://purl.flvc.org/fau/fd/FA00007681
Format: Document (PDF)

Title: 2012-2013 Program Review Complex Systems.
Creator: Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2012-2013
PURL: http://purl.flvc.org/fau/fd/FA00007688
Format: Document (PDF)

Title: 2013-2014 Program Review Complex Systems.
Creator: Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2013-2014
PURL: http://purl.flvc.org/fau/fd/FA00007695
Format: Document (PDF)

Title: 2014-2015 Program Review Complex Systems.
Creator: Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2014-2015
PURL: http://purl.flvc.org/fau/fd/FA00007702
Format: Document (PDF)

Title: 2015-2016 Program Review Complex Systems.
Creator: Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2015-2016
PURL: http://purl.flvc.org/fau/fd/FA00007709
Format: Document (PDF)

Title: 2016-2017 Program Review Complex Systems.
Creator: Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Florida Atlantic University Departmental Dashboard Indicators. Department program reviews for Charles E. Schmidt College of Science, Florida Atlantic University.
Date Issued: 2016-2017
PURL: http://purl.flvc.org/fau/fd/FA00007716
Format: Document (PDF)

Title: A CELL BIOLOGICAL AND ELECTROPHYSIOLOGICAL STUDY OF MOUSE RETINA.
Creator: Sullivan, James P., Shen, Wen, Prentice, Howard, Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Both proliferative diabetic retinopathy and exudative age-related macular degeneration are major causes of blindness which are caused by growth of defective, leaky and tortuous blood vessels in the retina. Hypoxia is implicated in triggering both of these diseases and results in induction of HIF-1alpha transcription factor in addition to the angiogenic factor VEGF. Müller cells are the major glial cell in the retina and they contribute to neovascularization in hypoxic regions of the retina...
Show moreBoth proliferative diabetic retinopathy and exudative age-related macular degeneration are major causes of blindness which are caused by growth of defective, leaky and tortuous blood vessels in the retina. Hypoxia is implicated in triggering both of these diseases and results in induction of HIF-1alpha transcription factor in addition to the angiogenic factor VEGF. Müller cells are the major glial cell in the retina and they contribute to neovascularization in hypoxic regions of the retina through eliciting secretion of growth factors, cytokines and angiogenic factors. As Müller cells span the breadth of the retina they can secrete angiostatic factors as well as neuroprotective trophic factors, the Müller cell is a valuable cell type for targeting by potential new gene therapies. The current investigation tests the hypoxia responsiveness of an AAV vector containing a hybrid hypoxia response element together with a GFAP promoter, and this vector encodes the angiostatic protein decorin, a well characterized multi-receptor tyrosine kinase inhibitor. Decorin may have advantages over other key angiostatic factors such as endostatin or angiostatin by virtue of its multiple anti-angiogenic signaling modalities. We employed Q-RT-PCR to evaluate the cell specificity and hypoxia responsiveness of an AAV-Vector termed AAV-REG-Decorin containing a hybrid HRE and GFAP promoter driving expression of the decorin transgene. The vector also contains a silencer element between the HRE and the GFAP domains to enable low basal expression in normoxia as well as high level inducibility in hypoxia. AAV-REGDecorin was found to elicit high level expression of decorin mRNA in hypoxia with greater than 9 – fold induction of the transgene in hypoxic conditions in astrocytes by comparison to normoxic astrocytes. AAV-REG-Decorin showed low levels of transgene expression by comparison to the positive control vector AAV-CMV -decorin containing the ubiquitously active CMV-promoter. The expression levels of decorin mRNA from AAV-REG-Decorin and from AAV-GFAP-Decorin were low in the PC12 neuronal cell model and in the ARPE19 line of retinal pigment epithelial cells with respect to those of AAV-CMV-decorin and no induction of Decorin mRNA was found with AAV-REGDecorin in these two control cell lines. Our novel gene therapy vector will serve as a platform for testing efficacy in rodent disease models (OIR and laser induced choroidal neovascularization) for assessment of the benefits of tightly regulated antiangiogenic gene therapy eliciting decorin transgene expression, both in terms of timing and the cellular source of production, during the progression of the retinal pathophysiology.
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Date Issued: 2021
PURL: http://purl.flvc.org/fau/fd/FA00013725
Subject Headings: Macular Degeneration, Retina, Gene therapy, Decorin
Format: Document (PDF)

Title: A COMPARISON OF TASK RELEVANT NODE IDENTIFICATION TECHNIQUES AND THEIR IMPACT ON NETWORK INFERENCES: GROUP-AGGREGATED, SUBJECT-SPECIFIC, AND VOXEL WISE APPROACHES.
Creator: Falco, Dimitri, Bressler, Steven L., Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: The dissertation discusses various node identification techniques as well as their downstream effects on network characteristics using task-activated fMRI data from two working memory paradigms: a verbal n-back task and a visual n-back task. The three node identification techniques examined within this work include: a group-aggregated approach, a subject-specific approach, and a voxel wise approach. The first chapters highlight crucial differences between group-aggregated and subject-specific...
Show moreThe dissertation discusses various node identification techniques as well as their downstream effects on network characteristics using task-activated fMRI data from two working memory paradigms: a verbal n-back task and a visual n-back task. The three node identification techniques examined within this work include: a group-aggregated approach, a subject-specific approach, and a voxel wise approach. The first chapters highlight crucial differences between group-aggregated and subject-specific methods of isolating nodes prior to undirected functional connectivity analysis. Results show that the two techniques yield significantly different network interactions and local network characteristics, despite having their network nodes restricted to the same anatomical regions. Prior to the introduction of the third technique, a chapter is dedicated to explaining the differences between a priori approaches (like the previously introduced group-aggregated and subject-specific techniques) and no a priori approaches (like the voxel wise approach). The chapter also discusses two ways to aggregate signal for node representation within a network: using the signal from a single voxel or aggregating signal across a group of neighboring voxels. Subsequently, a chapter is dedicated to introducing a novel processing pipeline which uses a data driven voxel wise approach to identify network nodes. The novel pipeline defines nodes using spatial temporal features generated by a deep learning algorithm and is validated by an analysis showing that the isolated nodes are condition and subject specific. The dissertation concludes by summarizing the main takeaways from each of the three analyses as well as highlighting the advantages and disadvantages of each of the three node identification techniques.
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Date Issued: 2020
PURL: http://purl.flvc.org/fau/fd/FA00013553
Subject Headings: Functional magnetic resonance imaging, Brain mapping, Working memory, Neural networks (Neurobiology), Neuroimaging--methods
Format: Document (PDF)

Title: A theory for the visual perception of object motion.
Creator: Norman, Joseph W., Barenholtz, Elan, Florida Atlantic University, Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description: The perception of visual motion is an integral aspect of many organisms' engagement with the world. In this dissertation, a theory for the perception of visual object-motion is developed. Object-motion perception is distinguished from objectless-motion perception both experimentally and theoretically. A continuoustime dynamical neural model is developed in order to generalize the ndings and provide a theoretical framework for continued re nement of a theory for object-motion perception....
Show moreThe perception of visual motion is an integral aspect of many organisms' engagement with the world. In this dissertation, a theory for the perception of visual object-motion is developed. Object-motion perception is distinguished from objectless-motion perception both experimentally and theoretically. A continuoustime dynamical neural model is developed in order to generalize the ndings and provide a theoretical framework for continued re nement of a theory for object-motion perception. Theoretical implications as well as testable predictions of the model are discussed.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004221, http://purl.flvc.org/fau/fd/FA00004221
Subject Headings: Human information processing, Neurophysiology, Perceptual motor processes, Visual perception
Format: Document (PDF)

Title: Analyzing connectivity patterns and their application to genetic networks.
Creator: Shehadeh, Lina A., Florida Atlantic University, Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description: The connectivity underlying a complex system determines its global dynamics and its observable functional patterns. Examples are found in a variety of disciplines such as social networks, the Internet, the central nervous system including the cortex, as well as electronic circuits. Novel computational methods from fractal mathematics and "small world" networks provide an entry point to the understanding of the connectiyity and the interaction of its microscopic components from the study of...
Show moreThe connectivity underlying a complex system determines its global dynamics and its observable functional patterns. Examples are found in a variety of disciplines such as social networks, the Internet, the central nervous system including the cortex, as well as electronic circuits. Novel computational methods from fractal mathematics and "small world" networks provide an entry point to the understanding of the connectiyity and the interaction of its microscopic components from the study of the observable variables on the macroscopic system level. As an example of such an approach, we try to understand the underlying connectivity of the genome by analyzing the observable patterns of gene expression profiles made available by cDNA microarrays technology. We start by formulating different models of genetic interactions on a genomic scale and then we compute the statistics of gene expression levels produced from each model. By these means tire obtain a dictionary relating different connection topologies on the microscopic level to corresponding gene expression profiles on the macroscopic system level. To allow for comparison between theory and experiment, we compute the equivalent statistics of experimental cDNA microarrays data obtained from the public domain. Reading the theoretical dictionary backwards and applying it to the statistics of the experimental data, we are able to rule out improbable genetic connectivity patterns and identify the most promising candidates of genetic networks. Our results show that the most promising candidate of genetic network is the "small world" heterogeneous network where the value of the scaling exponent in g(k) = Ak-a is between three halves and six, 3/2 < a < 6. This conclusion is quantitatively supported by the measures of goodness of fit of the models to the experimental data. This would imply that some genes are regulated by the input from a few other genes, while some genes are regulated by the input from many other genes. However, all the genes have a similar pattern of regulatory output onto other genes. We also find that in our genetic interaction models the clustering of the input pattern of the structural connectivity matrices is reflected in the correlation pattern of the functional connectivity matrices. Hence, the model predicts a direct connection between the regulatory links among genes and the co-expression of these genes.
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Date Issued: 2002
PURL: http://purl.flvc.org/fau/fd/FADT12007
Subject Headings: Biology, Biostatistics
Format: Document (PDF)

$Applications of fractals and scaling in population and settlement analysis$

Title: Applications of fractals and scaling in population and settlement analysis.
Creator: Sambrook, Roger Curtis, Florida Atlantic University, Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description: Patterns of settlement are examined using a number of fractal and scaling techniques. Existing methods of spatial analysis are reviewed and evaluated, showing a need for additional methods for the analysis of spatial and geographical data. Fractal methods are introduced as candidates for such uses. They are applied in a variety of ways to analyze patterns of population and settlement: in an exploratory fashion, to test hypotheses, to determine correlations, to validate settlement models, and...
Show morePatterns of settlement are examined using a number of fractal and scaling techniques. Existing methods of spatial analysis are reviewed and evaluated, showing a need for additional methods for the analysis of spatial and geographical data. Fractal methods are introduced as candidates for such uses. They are applied in a variety of ways to analyze patterns of population and settlement: in an exploratory fashion, to test hypotheses, to determine correlations, to validate settlement models, and to explore the dynamics of population. Scaling properties of population and settlement patterns averaged over different regions are found to be non-uniform, allowing comparisons to be made between them. Correlations are discovered between the scaling behavior of settlement patterns and physical factors such as proximity to coastlines and the ruggedness of the landscape. Popular stochastic and central place models are shown to be inadequate for explaining the scaling behavior of real settlement patterns. Finally patterns of population change are examined, compared and described in terms of their scaling properties. This paper demonstrates how fractal and scaling methods can be usefully applied in the social and spatial sciences. Such an exploratory analysis of the scaling behavior of patterns of human population and settlement constitutes a necessary first step toward a detailed understanding of these phenomena.
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Date Issued: 2002
PURL: http://purl.flvc.org/fau/fd/FADT12017
Subject Headings: Sociology, Theory and Methods, Geography
Format: Document (PDF)

Title: Attentional and affective responses to complex musical rhythms.
Creator: Chapin, Heather L., Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description: I investigated how two types of rhythmic complexity, syncopation and tempo fluctuation, affect the neural and behavioral responses of listeners. The aim of Experiment 1 was to explore the role of attention in pulse and meter perception using complex rhythms. A selective attention paradigm was used in which participants attended either to a complex auditory rhythm or a visually presented list of words. Performance on a reproduction task was used to gauge whether participants were attending to...
Show moreI investigated how two types of rhythmic complexity, syncopation and tempo fluctuation, affect the neural and behavioral responses of listeners. The aim of Experiment 1 was to explore the role of attention in pulse and meter perception using complex rhythms. A selective attention paradigm was used in which participants attended either to a complex auditory rhythm or a visually presented list of words. Performance on a reproduction task was used to gauge whether participants were attending to the appropriate stimulus. Selective attention to rhythms led to increased BOLD (Blood Oxygen Level-Dependent) responses in basal ganglia, and basal ganglia activity was observed only after the rhythms had cycled enough times for a stable pulse percept to develop. These observations show that attention is needed to recruit motor activations associated with the perception of pulse in complex rhythms. Moreover, attention to the auditory stimulus enhanced activity in an attentional sensory network including primary auditory, insula, anterior cingulate, and prefrontal cortex, and suppressed activity in sensory areas associated with attending to the visual stimulus. In Experiment 2, the effect of tempo fluctuation in expressive music on emotional responding in musically experienced and inexperienced listeners was investigated. Participants listened to a skilled music performance, including natural fluctuations in timing and sound intensity that musicians use to evoke emotional responses, and a mechanical performance of the same piece, that served as a control. Participants reported emotional responses on a 2-dimensional rating scale (arousal and valence), before and after fMRI scanning. During fMRI scanning, participants listened without reporting emotional responses. Tempo fluctuations predicted emotional arousal ratings for all listeners., Expressive performance was associated with BOLD increases in limbic areas for all listeners and in limbic and reward related areas forthose with musical experience. Activity in the dorsal anterior cingulate, which may reflect temporal expectancy, was also dependent on the musical experience of the listener. Changes in tempo correlated with activity in a mirror neuron network in all listeners, and mirror neuron activity was associated with emotional arousal in experienced listeners. These results suggest that emotional responding to music occurs through an empathic motor resonance.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/368606
Subject Headings: Perceptual-motor learning, Musical perception, Computational neuroscience, Emotions in music, Music, Psychological aspects
Format: Document (PDF)

Title: BEHAVIORAL ANALYSIS OF DEEP CONVOLUTIONAL NEURAL NETWORKS FOR IMAGE CLASSIFICATION.
Creator: Clark, James Alex, Barenholtz, Elan, Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Within Deep CNNs there is great excitement over breakthroughs in network performance on benchmark datasets such as ImageNet. Around the world competitive teams work on new ways to innovate and modify existing networks, or create new ones that can reach higher and higher accuracy levels. We believe that this important research must be supplemented with research into the computational dynamics of the networks themselves. We present research into network behavior as it is affected by: variations...
Show moreWithin Deep CNNs there is great excitement over breakthroughs in network performance on benchmark datasets such as ImageNet. Around the world competitive teams work on new ways to innovate and modify existing networks, or create new ones that can reach higher and higher accuracy levels. We believe that this important research must be supplemented with research into the computational dynamics of the networks themselves. We present research into network behavior as it is affected by: variations in the number of filters per layer, pruning filters during and after training, collapsing the weight space of the trained network using a basic quantization, and the effect of Image Size and Input Layer Stride on training time and test accuracy. We provide insights into how the total number of updatable parameters can affect training time and accuracy, and how “time per epoch” and “number of epochs” affect network training time. We conclude with statistically significant models that allow us to predict training time as a function of total number of updatable parameters in the network.
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Date Issued: 2022
PURL: http://purl.flvc.org/fau/fd/FA00013940
Subject Headings: Neural networks (Computer science), Image processing
Format: Document (PDF)

Title: Behavioral and electroencephalographic analysis of visuomotor coordination.
Creator: Taylor, Debra, Florida Atlantic University, Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description: Sensorimotor coordination is used in everyday behavior. This includes discrete reactive behaviors, such as maneuvers made to avoid a predator that was heard in the distance, or continuous rhythmic behaviors, such as riding a bicycle. Researchers have studied the behavioral aspects of sensorimotor coordination for over a century and various models have been proposed to account for these findings in terms of the nervous system. The purpose of this thesis was to use behavioral measures and...
Show moreSensorimotor coordination is used in everyday behavior. This includes discrete reactive behaviors, such as maneuvers made to avoid a predator that was heard in the distance, or continuous rhythmic behaviors, such as riding a bicycle. Researchers have studied the behavioral aspects of sensorimotor coordination for over a century and various models have been proposed to account for these findings in terms of the nervous system. The purpose of this thesis was to use behavioral measures and electroencephalographic (EEG) recordings in humans to address several of the remaining issues regarding the spatiotemporal dynamics of cortical activity involved in continuous sensorimotor coordination. First, are the spatiotemporal patterns of cortical activity different for discrete and continuous coordination behaviors? To investigate discrete coordination, a simple reaction time (RT) task was used: upon each random presentation of the visual stimulus (2.5--3.5 sec ISI), subjects responded with a unimanual index finger flexion. Continuous coordination was studied via a synchronization-continuation paradigm, which used the same visual stimulus (1 sec ISI) and the same unimanual index finger flexion as in the reaction time task. By keeping the stimulus and motor properties constant for the two types of coordination it was hypothesized that differences in cortical activity would relate to an internal timekeeping system responsible for pacing the rhythmic movements made during continuous coordination. Several models postulate that oscillatory activity is used by the brain for maintaining task timing information (see Miall, 1989, and Church and Broadbent, 1991, for example). Frequency analysis revealed phase-locking of the alpha rhythm in the occipital lobe. This rhythm appears to play a role as a neural timekeeper mechanism: it was found that the degree of alpha phase-locking was predictable from the expected dependence on neural timekeeping, i.e. continuation was greater than synchronization, which is in turn was greater than reaction. These results also support the concept of modality specificity in neural timekeeping mechanisms (reviewed in Matell and Meck, 2004). Furthermore, the behavioral and EEG results support the theory that continuous sensorimotor coordination is largely influenced by timekeeping mechanisms, with sensory stimulation being employed occasionally to keep timing relatively accurate (Hary and Moore, 1987).
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Date Issued: 2005
PURL: http://purl.flvc.org/fcla/dt/12143
Subject Headings: Psychology, Experimental, Psychology, Cognitive
Format: Document (PDF)

Title: Behavioral and Electrophysiological Properties of Nucleus Reuniens: Role in Arousal, Spatial Navigation and Cognitive Processes.
Creator: Viena, Tatiana Danela, Vertes, Robert P., Florida Atlantic University, Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description: The hippocampal-medial prefrontal circuit has been shown to serve a critical role in decision making and goal directed actions. While the hippocampus (HF) exerts a direct influence on the medial prefrontal cortex (mPFC), there are no direct return projections from the mPFC to the HF. The nucleus reuniens (RE) of the midline thalamus is strongly reciprocally connected with the HF and mPFC and represents the major link between these structures. We investigated the role of RE in functions...
Show moreThe hippocampal-medial prefrontal circuit has been shown to serve a critical role in decision making and goal directed actions. While the hippocampus (HF) exerts a direct influence on the medial prefrontal cortex (mPFC), there are no direct return projections from the mPFC to the HF. The nucleus reuniens (RE) of the midline thalamus is strongly reciprocally connected with the HF and mPFC and represents the major link between these structures. We investigated the role of RE in functions associated with the hippocampus and the mPFC -- or their interactions. Using two different inactivation techniques (pharmacological and chemogenetic), we sought to further define the role of RE in spatial working memory (SWM) and behavioral flexibility using a modified delayed non-match to sample (DNMS) working memory task. We found that the reversible inactivation of RE with muscimol critically impaired SWM performance, abolished well-established spatial strategies and produced a profound inability to correct non-rewarded, incorrect choices on the T-maze (perseverative responding). We observed similar impairments in SWM following the chemogenetic (DREADDs) inactivation of RE or selective RE projections to the ventral HF. In addition, we showed that the inhibition of RE terminals to the dorsal or ventral HF altered task related behaviors by increasing or decreasing the time to initiate the task or reach the reward, respectively. Finally, we examined discharge properties of RE cells across sleep-wake states in behaving rats. We found that the majority of RE cells discharge at high rates of activity in waking and REM and at significantly reduced rates in SWS, with a subpopulation firing rhythmically in bursts during SWS. We identified five distinct subtypes of RE cells that discharged differently across vigilant states; those firing at highest rates in waking (W1, W2), in REM sleep (R1, R2) and SWS (S1). Given the differential patterns of activity of these cells, we proposed they may serve distinct functions in waking – and possibly in SWS/REM sleep. In sum, our findings indicate that RE is critically involved in mnemonic and executive functions and the heterogeneous activity of these cells support a role for RE in arousal/attention, spatial working memory and cognition.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013139
Subject Headings: Midline Thalamic Nuclei, Hippocampus, Prefrontal cortex, Neural pathways, Arousal (Physiology), Space Perception, Cognition
Format: Document (PDF)

Title: Brain dynamics and behavioral basis of a higher level cognitive task: number comparison.
Creator: Ballan, Meltem., Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description: Number perception, its neural basis and its relationship to how numerical stimuli are presented have been challenging research topics in cognitive neuroscience for many years. A primary question that has been addressed is whether the perception of the quantity of a visually presented number stimulus is dissociable from its early visual perception. The present study examined the possible influence of visual quality judgment on quantity judgments of numbers. To address this issue, volunteer...
Show moreNumber perception, its neural basis and its relationship to how numerical stimuli are presented have been challenging research topics in cognitive neuroscience for many years. A primary question that has been addressed is whether the perception of the quantity of a visually presented number stimulus is dissociable from its early visual perception. The present study examined the possible influence of visual quality judgment on quantity judgments of numbers. To address this issue, volunteer adult subjects performed a mental number comparison task in which two-digit stimulus numbers (Arabic number format), among the numbers between 31 and 99 were mentally compared to a memorized reference number, 65. Reaction times (RTs) and neurophysiological (i.e. electroencephalographic (EEG) data) responses were acquired simultaneously during performance of the two-digit number comparison task. In this particular quantity comparison task, the number stimuli were classified into three distance factors. That is, numbers were a close, medium or far distance from the reference number (i.e., 65). In order to evaluate the relationship between numerical stimulus quantity and quality, the number stimuli were embedded in varying degrees of a typical visual noise form, known as "salt and pepper noise" (e.g., the visual noise one perceives when viewing a photograph taken with a dusty camera lens). In this manner, the visual noise permitted visual quality to be manipulated across three levels: no noise, medium noise (approximately 60% degraded visual quality from nonoise), and dense noise (75% degraded visual quality from no-noise)., The RTs provided the information about the overt responses; however, the temporal relationship of visual quality (starts earlier than quantity perception) and quantity were examined using eventrelated potentials (ERPs) extracted from continuous EEG recordings. The analysis of the RTs revealed that the judgment of number quantity is dependent upon visual number quality. In addition, the same effect was observed over the ERP components occurring between 100 ms and 300 ms after stimulus onset time over the posterior electrodes. Principal components analysis (PCA) and independent component analysis (ICA) methods were used to further analyze the ERP data. The consistent results of the PCA and ICA were used to represent the spatial brain dynamics, as well as to obtain temporal dynamics. The overall conclusion of the present study is that ERPs, ICs and PCs along with RTs suggested a strategy of quantitative perception (i.e., number comparison) based on the qualitative attributes of the stimuli highlighting the importance of the design of the task and the methodology
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Date Issued: 2010
PURL: http://purl.flvc.org/FAU/2867328
Subject Headings: Cognitive neuroscience, Learning, Physiological aspects, Visual perception, Information visualization, Mathematics, Philosophy
Format: Document (PDF)

Title: COMPUTATION IN SELF-ATTENTION NETWORKS.
Creator: Morris, Paul, Barenholtz, Elan, Florida Atlantic University, Center for Complex Systems and Brain Sciences, Charles E. Schmidt College of Science
Abstract/Description: Neural network models with many tunable parameters can be trained to approximate functions that transform a source distribution, or dataset, into a target distribution of interest. In contrast to low-parameter models with simple governing equations, the dynamics of transformations learned in deep neural network models are abstract and the correspondence of dynamical structure to predictive function is opaque. Despite their “black box” nature, neural networks converge to functions that...
Show moreNeural network models with many tunable parameters can be trained to approximate functions that transform a source distribution, or dataset, into a target distribution of interest. In contrast to low-parameter models with simple governing equations, the dynamics of transformations learned in deep neural network models are abstract and the correspondence of dynamical structure to predictive function is opaque. Despite their “black box” nature, neural networks converge to functions that implement complex tasks in computer vision, Natural Language Processing (NLP), and the sciences when trained on large quantities of data. Where traditional machine learning approaches rely on clean datasets with appropriate features, sample densities, and label distributions to mitigate unwanted bias, modern Transformer neural networks with self-attention mechanisms use Self-Supervised Learning (SSL) to pretrain on large, unlabeled datasets scraped from the internet without concern for data quality. SSL tasks have been shown to learn functions that match or outperform their supervised learning counterparts in many fields, even without task-specific finetuning. The recent paradigm shift to pretraining large models with massive amounts of unlabeled data has given credibility to the hypothesis that SSL pretraining can produce functions that implement generally intelligent computations.
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Date Issued: 2022
PURL: http://purl.flvc.org/fau/fd/FA00014061
Subject Headings: Neural networks (Computer science), Machine learning, Self-supervised learning
Format: Document (PDF)

Title: Contextual influences on real-time processing of linguistic stimuli: Traditional and dynamical approaches.
Creator: Raczaszek, Joanna, Florida Atlantic University, Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description: This work examines contextual influences on processing of linguistic stimuli. The traditional (symbolic) models of context influences are reviewed and their shortcomings pointed out. The dynamical approach, recently emerging in the area of behavioral sciences, is suggested as a viable alternative. Two studies follow. In the first one we use the case of perception of ambiguous sentences to show that perception of linguistic stimuli is the outcome of an underlying dynamical process. Thus it may...
Show moreThis work examines contextual influences on processing of linguistic stimuli. The traditional (symbolic) models of context influences are reviewed and their shortcomings pointed out. The dynamical approach, recently emerging in the area of behavioral sciences, is suggested as a viable alternative. Two studies follow. In the first one we use the case of perception of ambiguous sentences to show that perception of linguistic stimuli is the outcome of an underlying dynamical process. Thus it may be better described in dynamical terms, employing notions such as multistability and differential coherence of patterns, than in the traditional, symbolic framework. The second study is an on-line investigation of contextual adaptation. We studied general category names embedded in neutral or biasing sentential contexts. The results obtained indicate that the initial lexical access is context independent. The relative availability of particular members of category suggests that the initial state is best captured by a multistable representation, which may be essential for the flexibility of linguistic processing. Contextual adaptation seems to occur later in the unfolding sentence. A more detailed investigation into the timing and nature of contextual adaptation suggests that this adaptation takes the form of rapid reorganization of conceptual information rather than just facilitation of relevant category members. The results of the studies presented have implications both for dynamical and psycholinguistic approaches. The main implication for the dynamical approach is the importance of using on-line methods in studies of perception. Dynamical studies that use off-line methods perhaps miss an important stage of processing: a transition from locally invariant to contextually congruent organization of information. For psycholinguistics the characterization of language processing as pattern formation has at least three major advantages: (1) capturing the timing of the processes allows for including distinctions between fast/slow, linear/nonlinear processing, (2) conceptualization of the initially available lexical information as a constraint on possible meanings rather than meaning itself allows for accounting for apparently contradictory psycholinguistic data, (3) adding the dimension of stability of the patterns generated during language processing makes possible new predictions regarding speed and variability of performance on various psycholinguistic tasks.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/12434
Subject Headings: Language, Linguistics, Psychology, Experimental
Format: Document (PDF)

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