Changes in resting-state functionally connected parieto-frontal networks after videogame practice

Neuroimaging studies provide evidence for organized intrinsic activity under task-free conditions. This activity serves functionally relevant brain systems supporting cognition. Here, we analyze changes in resting-state functional connectivity after videogame practice applying a test–retest design. Twenty young females were selected from a group of 100 participants tested on four standardized cognitive ability tests. The practice and control groups were carefully matched on their ability scores. The practice group played during two sessions per week across 4 weeks (16 h total) under strict supervision in the laboratory, showing systematic performance improvements in the game. A group independent component analysis (GICA) applying multisession temporal concatenation on test–retest resting-state fMRI, jointly with a dual-regression approach, was computed. Supporting the main hypothesis, the key finding reveals an increased correlated activity during rest in certain predefined resting state networks (albeit using uncorrected statistics) attributable to practice with the cognitively demanding tasks of the videogame. Observed changes were mainly concentrated on parietofrontal networks involved in heterogeneous cognitive functions

Differences in verbal and visuospatial forward and backward order recall: A review of the literature

How sequential, verbal and visuospatial stimuli are encoded and stored in memory is not clear in cognitive psychology. Studies with order recall tasks, such as the digit, and Corsi span, indicate that order of presentation is a crucial element for verbal memory, but not for visuospatial memory. This seems to be due to the different effects of forward and backward recall in verbal and visuospatial tasks. In verbal span tasks, performance is worse when recalling things in backward sequence rather than the original forward sequence. In contrast, when it comes to visuospatial tasks, performance is not always worse for a modified backward sequence. However, worse performance in backward visuospatial recall is evident in individuals with weak visuospatial abilities; such individuals perform worse in the backward version of visuospatial tasks than in the forward version. The main aim of the present review is to summarize findings on order recall in verbal and visuospatial materials by considering both cognitive and neural correlates. The results of this review will be considered in the light of the current models of WM, and will be used to make recommendations for future studie

Spatiotemporal patterns of parietofrontal activity and eye movements underlying the visual perception of complex human tool use

When watching a child learning to use a spoon, a mother is immediately able to recognize the error when the child grabs the bowl rather than the stem, or when the child uses the spoon to try and scoop paper. Recognizing proper tool grasp-postures and use-contexts is an ability vital for daily life and can be lost due to brain injury. A better understanding of how the brain encodes contextual and grasp-specific tool-use not only furthers basic neuroscience, but also has strong relevance to deficits arising from neural pathologies. However, the majority of research till date has studied the neural response to viewing tools in isolation or viewing simple tool-grasps. These studies have shown that the recognition of tools to be a complex visuomotor process, as not only was the visual cortex engaged but also parietal and frontal regions that underlie actual tool-use. The recognition of tools therefore involves automatically recalling their motor information (graspability and manipulability) via activation of parietofrontal motor regions, a property called action affordances. Yet, it is still unclear how parietofrontal regions encode the combination of contextual and grasp-specific tool-use scenes. In addition, parietofrontal regions are multifaceted and also underlie visuospatial attention and eye movements. It is possible a relationship might exist between eye movements, attention and tool-use understanding over parietofrontal regions. Therefore the overall goal of this thesis was to understand the spatiotemporal patterns of parietofrontal activity and eye movements underlying the perceptual of contextual and grasp-specific static tool use images. Electroencephalography (EEG) was used to measure neural activity, combined with eye tracking to measure fixation and saccades. Overall, results from this thesis present evidence that the affordances of non-functional grasp-postures perturbed an observer from understanding the contextual uses of tools, with corresponding unique patterns of parietofrontal activity and eye movements. This effect was most robust when the tool was placed in contexts that afforded a certain degree of tool-use. Results also revealed a relationship between attention, eye movements and action perception over parietofrontal regions. Specifically, saccades perturbed activity over frontal regions during the perception of non-functional grasp postures and in addition, there was greater engagement of the left precuneus in the superior parietal lobe if the observer had to quickly parse the scene information using peripheral vision and rely on short term memory. In contrast, there was greater engagement of the left middle temporal gyrus if the observer had the ability to parse scene information continuously using foveal attention. Results in this thesis shed light on the neural and visual mechanisms in understanding the affordances of non-functional grasp postures, and the relation between the two mechanisms. The automatic sensitivity in understanding the intent of non-functional grasp-postures may correspond to a lifetime of learning the affordances of grasp-specific action outcomes with tools. Such cognitive motor knowledge may be vital in navigating a human environment almost entirely constructed on advanced tool-use knowledge and findings from this thesis have many potential applications in the field of neuro-rehabilitation.Ph.D

Neural Mechanisms of Transsaccadic Integration of Visual Features

This thesis explores the neural mechanisms of transsaccadic integration of visual features. In the study, I investigated the cortical correlates of transsaccadic integration of object orientation in multiple reference frames. In a functional MRI adaptation (fMRIa) paradigm, participants viewed sets of two orientation stimuli in each trial and were asked to indicate if the orientations were the same (Repeat condition) or different (Novel condition). Stimuli were presented in one of three spatial conditions: 1) space-fixed, 2) retina-fixed and 3) frame-independent. Results indicate that, in addition to common activation in frontal motor cortical regions in all three spatial conditions, parietal and occipitotemporal regions are active in the space-fixed condition, parietofrontal regions are active in the retina-fixed condition, and parietofrontal and occipitotemporal regions are active in the frame-independent condition. In conclusion, these results indicate that transsaccadic integration involves differential activation of cortical areas, depending on the frame of reference

Differences in Verbal and Visuospatial Forward and Backward Order Recall: A Review of the Literature.

How sequential, verbal and visuospatial stimuli are encoded and stored in memory is not clear in cognitive psychology. Studies with order recall tasks, such as the digit, and Corsi span, indicate that order of presentation is a crucial element for verbal memory, but not for visuospatial memory. This seems to be due to the different effects of forward and backward recall in verbal and visuospatial tasks. In verbal span tasks, performance is worse when recalling things in backward sequence rather than the original forward sequence. In contrast, when it comes to visuospatial tasks, performance is not always worse for a modified backward sequence. However, worse performance in backward visuospatial recall is evident in individuals with weak visuospatial abilities; such individuals perform worse in the backward version of visuospatial tasks than in the forward version. The main aim of the present review is to summarize findings on order recall in verbal and visuospatial materials by considering both cognitive and neural correlates. The results of this review will be considered in the light of the current models of WM, and will be used to make recommendations for future studies

The cognitive neuroscience of visual working memory

Visual working memory allows us to temporarily maintain and manipulate visual information in order to solve a task. The study of the brain mechanisms underlying this function began more than half a century ago, with Scoville and Milner’s (1957) seminal discoveries with amnesic patients. This timely collection of papers brings together diverse perspectives on the cognitive neuroscience of visual working memory from multiple fields that have traditionally been fairly disjointed: human neuroimaging, electrophysiological, behavioural and animal lesion studies, investigating both the developing and the adult brain

Allocentric Versus Egocentric Representations for Visual Memory and Action in Human Cortex

In daily life, people frequently perform various aiming movements, such as reaching or making a saccade toward a cellphone. The early stage for executing such movements is to localize the target location precisely. A visual target can be represented and maintained in memory in two main reference frames: egocentric (body-fixed) or allocentric (world-fixed). However, the neural mechanisms for the allocentric spatial processing are poorly understood and for the Allo-Ego conversion are still unknown in humans. This thesis investigated the allocentric and egocentric mechanisms with a focus on target memory coding for reaching (study 1) and saccades (study 2) in healthy humans using event-related functional magnetic resonance imaging (fMRI) designs where the phase of memorized target representation was separated from the phase of motor planning and execution. I further examined neural substrates for Allo-Ego conversion of targets for reach in study 3 using different types of cues to specify reach target direction for two reach tasks before delay or response phases. I observed widely overlapping cortical areas in the egocentric and allocentric reach tasks as compared to the control, but higher activation in parietofrontal areas for the former, and higher activation in early visual areas for the latter. Further, directional selectivity in egocentric coordinates (target relative to gaze/midline) was observed in superior occipital and inferior occipital gyrus; on the other hand, directional selectivity in allocentric coordinates (target relative to a landmark) was revealed in inferior temporal gyrus and inferior occipital gyrus. These results indicate that different cortical mechanisms are involved in the representations of remembered reach targets. I found similar pattern of task-relevant activation and egocentric directional selectivity in the saccade study. However, different areas from those observed in the reach study showed allocentric directional selectivity of remembered saccade targets including precuneus and midposterior intraparietal sulcus, suggesting effector-specific (eye vs. hand) neural mechanisms. In study 3, I identified four areas in parietal and frontal cortex, i.e., posterior precuneus, angular gyrus, supramarginal gyrus and medial frontal gyrus that are specifically involved in converting allocentric target coding to egocentric representation as soon as the final target location for reach is specified

Neurophysiological Investigation of the Functional Interactions between Manual Action Control and Working Memory

Gündüz Can R. Neurophysiological Investigation of the Functional Interactions between Manual Action Control and Working Memory. Bielefeld: Universität Bielefeld; 2020

Visual attention and working memory in action

This doctoral thesis employed a psychophysical approach to investigate the relationship between goal-directed eye and hand movements, visual attention, and visual working memory. To establish a solid methodological basis for investigating visual attention, the first study compared the strengths and weaknesses of a set of discrimination stimuli frequently used in attention research (Chapter 2.1). Based on the results, we used a novel pink noise stimulus for approaching the following research questions concerning visual attention. In the second study, we investigated the dependence of attentional orienting on oculomotor programming (Chapter 2.2). Motivated by the claim that attention can only be allocated to locations reachable by saccadic eye movements, we measured visual sensitivity – a proxy for visual attention – within and beyond the oculomotor range using an eye abduction paradigm. Contrary to previous findings, we found that attention can be shifted without restriction to locations to which saccades cannot be executed, ruling out the necessity to program a saccadic eye movement as a prerequisite for spatial attention. The third study attempted to resolve the longstanding debate as to whether eye and hand movement targets are selected by a single attentional mechanism or by independent, effector-specific systems (Chapter 2.3). Results revealed that during simultaneous eye and hand movements, attention – an index of motor target selection – was allocated in parallel to the saccade and the reach targets. Motor target selection mechanisms moreover did not compete for attentional resources at any time during movement preparation, demonstrating that separate, effector-specific mechanisms attentionally select eye and hand movement targets. The fourth study tested the assumption of effector-specific selection mechanisms in the framework of visual working memory (Chapter 2.4). Participants memorized several locations and performed eye, hand, or simultaneous eye-hand movements during the maintenance interval. When participants performed an eye and a hand movement simultaneously to distinct locations, memory at both motor targets was enhanced with no tradeoff between the two. This suggests that the two effector systems improve working memory at their selected motor targets independently. In the final study, we dissociated the relative contributions of the two highly interdependent parameters, task relevance and oculomotor selection, to the memory benefits consistently observed at eye movement targets (Chapter 2.5). Participants memorized shapes while simultaneously either avoiding or selecting a specific location as a delayed saccade target. While oculomotor selection was consistently associated with an increased working memory performance, mere task relevance was not, indicating that the frequently reported memory benefits for task-relevant items might, in fact, be caused by oculomotor selection. In summary, goal-directed eye and hand movements selectively boost the visual processing of the currently most relevant information, and likewise bias our memory capacities according to behavioral priority. The observed motor-induced enhancements in both the attention and working memory domains appear to be independent and effector-specific, allowing for the most flexible assignment of our limited cognitive resources as we traverse through our crowded environment

Optic Ataxia: From Balint’s Syndrome to the Parietal Reach Region

Optic ataxia is a high-order deficit in reaching to visual goals that occurs with posterior parietal cortex (PPC) lesions. It is a component of Balint’s syndrome that also includes attentional and gaze disorders. Aspects of optic ataxia are misreaching in the contralesional visual field, difficulty preshaping the hand for grasping, and an inability to correct reaches online. Recent research in nonhuman primates (NHPs) suggests that many aspects of Balint’s syndrome and optic ataxia are a result of damage to specific functional modules for reaching, saccades, grasp, attention, and state estimation. The deficits from large lesions in humans are probably composite effects from damage to combinations of these functional modules. Interactions between these modules, either within posterior parietal cortex or downstream within frontal cortex, may account for more complex behaviors such as hand-eye coordination and reach-to-grasp