Oscillatory Network Dynamics in Perceptual Decision-Making

Synchronized oscillations of ensembles of neurons in the brain underlie human cognition and behaviors. Neuronal network oscillations can be described by the physics of coupled dynamical systems. This dissertation examines the dynamic network activities in two distinct neurocognitive networks, the salience network (SN) and the ventral temporal cortex-dorsolateral prefrontal cortex (VTC-DLPFC) network, during perceptual decision-making (PDM). The key nodes of the SN include the right anterior insula (rAI), left anterior insula (lAI), and dorsal anterior cingulate cortex (dACC) in the brain. When and how a sensory signal enters and organizes within the SN before reaching the central executive network including the prefrontal cortex has been a mystery. Second, prior studies also report that perception of visual objects (face and house) involves a network of the VTC—the fusiform face area (FFA) and para-hippocampal place area (PPA)—and the DLPFC. How sensory information enters and organizes within the VTC-DLPFC network is not well understood, in milliseconds time-scale of human’s perception and decision-making. We used clear and noisy face/house image categorization tasks and scalp electroencephalography (EEG) recordings to study the dynamics of these networks. We demonstrated that beta (13–30 Hz) oscillation bound the SN, became most active around 100 ms after the stimulus onset, the rAI acted as a main outflow hub within the SN, and the SN activities were negatively correlated with the difficult tasks. We also uncovered that the VTC-DLPFC network activities were mediated by beta (13-30 Hz) and gamma (30-100 Hz) oscillations. Beta activities were enhanced in the time frame 125-250 ms after stimulus onset, the VTC acted as main outflow hub, and network activities were negatively correlated with the difficult tasks. In contrast, gamma activities were elevated in the time frame 0-125 ms, the DLPFC acted as a main outflow hub, and network activities—specifically the FFA-PPA pair—were positively correlated with the difficult tasks. These findings significantly enhance our understanding of how sensory information enters and organizes within the SN and the VTC-DLPFC network, respectively in PDM

Perception and cognition in Parkinson's disease: a neural network perspective

Parkinson’s disease (PD) is a neurodegenerative disorder commonly presenting with perceptual and cognitive dysfunction. Whereas previous work in PD suggests that abnormal basal ganglia activity has profound effects on integrated functioning of widespread cortical networks, the relation of specific network functions to the perceptual and cognitive impairments is still poorly understood. Here, I present a series of fMRI investigations of network-level functioning in non-demented individuals with PD with the aim of elucidating these associations. Study 1 examined the neural correlates of optic flow processing in 23 individuals with PD and 17 age-matched control participants (MC). An optic flow network comprising visual motion areas V6, V3A, MT+ and visuo-vestibular areas PIVC and CSv is known to be important for parsing egomotion depth cues in humans. The hypothesis was that individuals with PD would show less activation in these regions than MC when processing optic flow. While MC participants showed robust activation in this network, PD participants showed diminished activity within MT+ and CSv. Diminished CSv activity also correlated with greater disease severity. Study 2 investigated intrinsic network organization in PD with a focus on the functional coupling among three neurocognitive networks: the default-mode network (DMN), the salience network (SN), and the central executive network (CEN). Twenty-four individuals with PD and 20 MC participants were scanned at rest. The hypothesis was that PD participants would demonstrate dysfunctional SN coupling with the DMN and CEN. Relative to MC, in PD the CEN was less positively coupled with the SN and less anti-correlated with the DMN. Study 3 investigated the association between functional coupling and cognition in the same group that participated in Study 2. As hypothesized, anti-correlated functional coupling between the SN and DMN was related to successful performance on tests of executive function, psychomotor speed, and memory retrieval in MC but not in PD, suggesting that dysfunction within these networks could underlie early cognitive deficits in PD. Together, the results from the three studies suggest that dysfunctional activity in cortical networks important for visual motion processing and neurocognitive efficiency may underlie aspects of perceptual and cognitive impairment in PD.2017-12-06T00:00:00

Effects of video game playing on sensorimotor decision-making abilities and brain network dynamics

Video game playing is a popular activity that provides a cognitively engaging, sensory rich, competitive environment. Sensorimotor decision-making is a dynamic brain process involving multiple steps that build to make and execute a choice. This dissertation examines the differences in brain mechanisms for decision-making between those who play video games extensively and those who do not for two studies. These studies of video gamers and non-gamers investigated the differences between commonly activated brain regions from both groups and the differences in brain network interactions. We used a modified moving dot left-right discrimination task to examine each group’s decision-making performance and functional magnetic resonance imaging (fMRI) to record the underlying brain activity associated with task completion. Participants had to make decisions about the direction (left or right) of motion of a specific set of color dots. Video game players (VGP) were found to be faster than non-video game players (NVGP) by approximately 190 milliseconds and overall approximately 2% more accurate. In the commonly activated regions study, we extracted the percent signal change above baseline due to task-induced activity. VGP showed higher levels of percent signal change than NVGP for primary and secondary visual areas and premotor and motor regions. Functional Connectivity (FC) analysis allowed us to examine if the activity from one correlates with the other. Examining FC for commonly activated regions, we found six undirected and four directed increased connections across those regions. We found that VGP displayed increased connections from DLPFC. These findings suggest that VGP perform better on decision-making tasks because of enhanced attention control and visuomotor coordination. For between network interactions, we examined previously studied decision-making related networks, CEN-SN-DMN, and attention switching networks, DAN-DMN-SN. VGP displayed decreased connectivity from SN to DAN, DMN, and CEN but showed increased connectivity to SN. These findings imply that VGP increases their performance by controlling the SN instead of SN controlling network interactions. These results provide an improved understanding of how cognitively engaging tasks, like video game playing, enhance our abilities to perform sensorimotor tasks even outside of video game playing

The Functional Role of the Anterior Insular Cortex in Cognitive Control

Cognitive control, a higher level psychological construct, refers to efficient coordination of thoughts and actions for the accomplishment of goal-directed behaviors. Cognitive control is supported by a commonly activated cognitive control network, and the anterior insular cortex (AIC) serves as one of its key structures. However, the functional role of the AIC in cognitive control has not been fully understood. A human lesion study was conducted to examine the necessary function of the AIC in cognitive control. A mouse optogenetic study with fiber photometry recording further examinedwhether the bilateral AIC was important for cognitive control and how the AIC played a role in different stages of cognitive control (e.g., state uncertainty processing, execution of control, or motor generation). Compatible versions of the post-target interference task consisting of congruent and incongruent conditions were used to measure cognitive control in humans and mice, respectively. In the human lesion study, the patients with lesions in the AIC showed longer overall response time (RT), lower overall processing efficiency, and greater conflict effects of RT and processing efficiency. These findings provided lesion-based evidence to support a causally necessary function of the AIC in cognitive control. In the mouse study, the accuracy of the congruent condition decreased when the AIC was silenced unilaterally or bilaterally by optogenetics after the cue sound and when the AIC was silenced bilaterally during the presentation of target and distractor stimuli, indicating that the disruption of the AIC resulted in a reduction in global processing efficiency. The fiber photometry results showed a significant decrease of the calcium-dependent signal after the cue sound compared to baseline, suggesting that the AIC was involved in state uncertainty processing. The results of the human lesion study identified the necessary role of the AIC in cognitive control. The findings of the mouse study further demonstrated the role of the AIC in cognitive control in both hemispheres and suggested a critical role of the AIC in state uncertainty processing

Evolutionary And Neural Network Mechanisms Of Visual Art Engagement

Engagement with the visual arts is a universal part of the human experience. By exploring the evolutionary advantages for artistic processes as well as the neural network interactions involved, this review illuminates why humans engage with the visual arts and how our brains allow us to do so. Coming up with creative ideas, tangibly executing them, and aesthetically evaluating artwork all require diverse modes of neurocognitive processing that interact in dynamic ways. As the modern human brain evolved and being able to make and evaluate visual artwork became advantageous to group cohesion and sexual selection, the development of large-scale neural networks facilitated artistic processes. Interactions between functionally diverse networks allows for integration of visual input, executive focus, association formation, salience discernment, emotional valence processing, and reward perception required for artistic processes. The central executive network computes behavior for the attainment of complex cognitive goals that require externally directed attention and inhibition of irrelevant stimuli. The default mode network is conversely activated by internally directed attention on self-referential, social, and intuitive information, spontaneously creating associations that guide artistic conceptualization and insight. While these two networks are functionally oppositional, both executive and spontaneous styles of processing are used within visual art processes; the salience network dynamically regulates activation of the central executive and default mode networks. The salience network additionally processes visual saliency and emotional valence and is interconnected with the dopaminergic reward system, which processes the hedonic value of engaging with art. Unique interactions between these brain networks facilitate visual art engagement, which is ingrained within human cultures for its valuable ability to promote social connection

Effect of visual attention on functional connectivity

In our environment, there are so many things to see, e.g., computer screen, buildings, trees and cars in the street. In this busy scenery, we do not process all the information equally, but rather filter out some information and focus more on certain characteristics in the whole scene. In this process, attention plays an important role, and underlying neural correlate is the matter of interest. We focus on investigating how attention changes the connectivity of the fMRI signal in the human brain. Prior studies examined this question, yet most studies used short trial interval (<20s) in examining the connectivity during attention. The short trial interval excludes the slow fMRI fluctuations (<0.1Hz) that showed segmented connectivity structure in the resting-state studies supported by the neurophysiological observations. In the thesis, we introduce an ultra-long trial (2-3mins) to examine connectivity during task conditions, in attention demanding task. In the first study, we asked whether trial length affects the functional connectivity (FC) strength in general during attention task compared to visually matched condition as control. We observed that the long trial interval (2mins) condition showed nearly twice the FC strength compared to short traditional trials (20s). Moreover, attention reorganized the FC as enhanced positive FC between dorsal attention network (DAN) and visual network (VIS) and decreased negative FC between default mode network (DMN) and DAN/VIS, but reduced positive FC within VIS. Notably, the reorganization is frequency dependent: FC changed relied more on slow frequency (0.004-0.05Hz) for the connection between DAN and VIS and high frequency (0.05-0.2Hz) for decorrelation within VIS. In the second study, we addressed the question whether FC strength relies on visual hierarchical distance in visual processing and attention task. We observed a gradient of connectivity, such that DAN connected strongly with high visual region (e.g., V5/MT) that degrades towards lower visual region (e.g., V1). A reversed effect was observed between DMN and VIS, revealing that DMN connected strongly negatively with high visual region that degrades its negative connectivity strength towards lower visual region. More interestingly, we implemented general linear model to the FC strength that showed attention modulates multiplicatively and addictively the connectivity strength along this visual hierarchy. In the third study, we observed how attention changes the connectivity in different features, e.g., color and motion attention. Here, we used seed-to-whole brain connectivity with regressing out the mean signal from the whole brain. First, we observed that V4 and V5/MT selectively connected to the task positive network, including DAN and visual regions, and negatively connected to the DMN. Then, feature-specific analysis showed that color compared to motion attention, selectively connects the V4 to DAN more than V5/MT to DAN, with selective negative connections between V4 and DMN than V5/MT and DMN. This suggest that feature-based attention led the brain communicate specifically cooperative (positive) way, but also competitive (negative) way. Taken together, attention not only reorganizes the connectivity in frequency dependent way, modulates differentially along the visual hierarchy as well as feature-specific manner. More interestingly, our results showed advantages of using long trial block experiment to detect important network connectivity change during attention. Not only applying frequency dependent analysis, but implementation of the GLM in comparing conditions, as well as, regressing out the mean signal from the whole brain for seed-to-whole brain connectivity analysis. All these methods that is used in the thesis can be extended to examine brain connectivity structure noninvasively, that may show important findings in other cognitive tasks, such as decision making or memory tasks

Vividness, Consciousness, and Mental Imagery

Today in many studies, mental images are still either treated as conscious by definition, or as empirical operations implicit to completing some type of task, such as the measurement of reaction time in mental rotation, an underlying mental image is assumed, but there is no direct determination of whether it is conscious or not. The vividness of mental images is a potentially helpful construct which may be suitable, as it may correspond to consciousness or aspects of the consciousness of images. In this context, a complicating factor seems to be the surprising variety in what is meant by the term vividness or how it is used or theorized. To fill some of the gaps, the goal of the present Special Issue is to create a publication outlet where authors can fully explore through sound research the missing theoretical and empirical links between vividness, consciousness and mental imagery across disciplines, neuroscience, psychology, philosophy, cognitive science, to mention the most obvious ones, as well as transdisciplinary methodological (single, combined, or multiple) approaches

Neurocognitive Development of the Resolution of Selective Visuo-Spatial Attention: Functional MRI Evidence From Object Tracking

Our ability to select relevant information from the environment is limited by the resolution of attention – i.e., the minimum size of the region that can be selected. Neural mechanisms that underlie this limit and its development are not yet understood. Functional magnetic resonance imaging (fMRI) was performed during an object tracking task in 7- and 11-year-old children, and in young adults. Object tracking activated canonical fronto-parietal attention systems and motion-sensitive area MT in children as young as 7 years. Object tracking performance improved with age, together with stronger recruitment of parietal attention areas and a shift from low-level to higher-level visual areas. Increasing the required resolution of spatial attention – which was implemented by varying the distance between target and distractors in the object tracking task – led to activation increases in fronto-insular cortex, medial frontal cortex including anterior cingulate cortex (ACC) and supplementary motor area, superior colliculi, and thalamus. This core circuitry for attentional precision was recruited by all age groups, but ACC showed an age-related activation reduction. Our results suggest that age-related improvements in selective visual attention and in the resolution of attention are characterized by an increased use of more functionally specialized brain regions during the course of development

Salience in decision-making: a neuroeconomic analysis

Attention and the closely related concept of salience play an important role in the complex process of human decision-making. In 2012, Bordalo et al. (2012a) proposed a theory on human decision-making that is based on salience. They suggest that salience differences within a decision problem may explain many decision biases. Concerning decisions under risk, Bordalo and colleagues developed a formula to calculate salience differences that are shaped by bottom-up processes. These salience differences have been experimentally investigated. Reaction times in a dot-probe task served as indicator of attentional biases. Data revealed a significant salience effect after a lottery exposure duration of 150 ms. This supports the salience concept proposed by Bordalo et al. (2012a) and suggests an early attentional orienting towards salient payoffs. In order to further differentiate attentional processes involved in the salience effect EEG has been recorded. Different ERP-components may indicate attentional biases at different stages of attentional processing and give a hint at more detailed reasons behind the salience effect. All investigated components, namely, P1, N1, P3a and P3b, showed no significant salience differences. Part III presents a further experiment that was devoted to nudges. These interventions often work by altering the salience within a decision problem or by directing the attention to the decision task itself. Since these interventions influence decisions at least partly on an unconscious level, nudges are subject to criticism. The experiment aimed at investigating the effect of transparent information accompanying the nudges on their efficacy. In line with previous research adding information on the nudge itself, on its purpose and the combination of both had no significant effect on the efficacy of the nudge, even though this additional information again alters salience ratios within the decision problem

How the Expressive Therapies Continuum Informs Intermodal Transfers

Expressive arts therapy (ExAT) is a therapeutic approach that incorporates visual art, music, drama, and dance/movement into the counseling environment. An essential element in ExAT practice is the intermodal transfer, an intentional shift between arts modalities to enhance clients’ understanding and realization. Currently, no theoretical guidelines for intermodal transfers exist in the field of ExAT. In search of a theoretical structure, the author of this Capstone Thesis proposed that the Expressive Therapies Continuum (ETC) informed intermodal transfers. Predominantly presented as an art therapy approach, the ETC originally intended to include all expressive therapies. Yet, there is minimal recent literature that directly connected the ETC with the therapeutic modalities of music, dance/movement, drama, and expressive arts. To further illustrate this relationship and suggest a potential framework for intermodal transfers, this literature review analyzed the ETC and linked it to each of the expressive therapies modalities through commonalities and neuroscience findings. The concepts and information gleaned through research confirmed and validated the ETC\u27s ability to inform ExAT intermodal transfers