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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Dynamics of temporal anticipation in perception and action

Heideman, Simone January 2017 (has links)
The selective deployment of attention over time optimises our perception and action at the moments when relevant events are expected to happen. Such "temporal orienting" to moments when something is going to happen is especially useful when this information can be combined with predictions about where and what events are likely to occur. A large body of research has already established how temporal predictions dynamically influence our perception and action, but questions remain regarding the neural bases of these attentional mechanisms. In this thesis I present three magnetoencephalography (MEG) studies that I conducted to investigate anticipatory neural dynamics associated with spatial-temporal orienting of attention for perception and action. I also investigate and discuss how such anticipatory dynamics change with ageing and neurodegeneration in Parkinson's disease (PD), and how these anticipatory neural dynamics behave in situations where a complex, hidden spatial-temporal structure is present. In Chapter 1, I introduce the topic of this thesis by reviewing the literature on temporal orienting of attention and by introducing my specific research questions. In Chapter 2, I present an MEG study on anticipatory neural dynamics of joint spatial-temporal orienting of attention in the visual domain, in younger and older adults. This study shows that neural dynamics with spatial, temporal and spatial-temporal orienting are all differentially affected by ageing. In Chapter 3, I describe an MEG experiment that investigates anticipatory neural dynamics during spatial-temporal motor preparation and compares PD participants to healthy control participants. This study reveals that both behavioural and neural dynamics with temporal orienting are affected in PD. In Chapter 4, I describe an experiment that explores how an implicit spatial-temporal structure is utilised to predict and prepare for upcoming actions. This study shows that motor cortical excitability is dynamically modulated in anticipation of the location and timing of events, even when such expectations are hidden in complex visual-motor sequences that remain largely implicit. In Chapter 5, the General discussion, I place these results in their wider context and discuss limitations and future directions.
192

Novel approaches to studying the role of the anterior cingulate cortex in cognition and Parkinson's disease

Weiss, Alexander R. January 2017 (has links)
The motor symptoms of Parkinson's disease (PD) have been linked to the emergence of exaggerated oscillatory activity in the 13 - 35 Hz beta range in recordings of the basal ganglia (BG) thalamocortical circuit of PD patients and animal models. PD patients and animal models also express dopamine-dependent cognitive impairments, implying effects of dopamine loss on the function of the anterior cingulate cortex (ACC). This thesis examines the electrophysiological behavior of the BG thalamocortical circuit in PD and dopamine-normal states during cognitive and motor activity. In vivo recordings in the BG of PD and dystonic patients were used to study the influence of dopamine during a test of executive function. Normal executive function was also investigated in the dopamine-healthy ACC of chronic pain patients. Both the BG and ACC exhibited lateralized electrophysiological responses to feedback valence. The BG also exhibited dopamine-sensitive event-related behavior. In additional experiments, chronically implanted recording electrodes in awake, behaving hemiparkinsonian rats were used to examine the transmission of synchronized oscillatory activity from the BG, through the ventral medial (VM) thalamus, to the ACC. Modulation of subthalamic nucleus, VM thalamus, and ACC activity during a simple cognitive/movement task was also investigated in hemiparkinsonian rats. Findings in the rat model suggest that ACC-mediated executive function is dopamine-sensitive and is reflected in the region's electrophysiology. These results may provide further insight into the significance of excessive oscillatory activity in PD and its influence on cognitive systems.
193

Cognitive and neural processes underlying memory for time and context

Persson, Bjorn Martin January 2017 (has links)
The aim of this thesis is to examine the underlying cognitive and neural processes at play during retrieval of temporal and contextual source information. This was assessed across three experimental chapters. In the first experimental chapter, Chapter 2, the neural loci of context associations were assessed. Rats trained on an odour-context association task were given lesions to either the Lateral Entorhinal Cortex (LEC) or sham lesions. After surgery, performance on the odour-context task was assessed. It was hypothesised that memory for previously learned odour-context associations would be impaired following LEC lesions but not sham lesions. The results supported this hypothesis, demonstrating impaired memory for the previously learned odour-context associations in the LEC lesion group compared to the Sham lesion. In Chapter 3, the underlying retrieval processes used to retrieve time and context in human memory was assessed across three experiments. It was hypothesised that time would be remembered accurately using both recollection and familiarity, while correct context memory should rely on recollection alone. Two out of the three experiments supported this hypothesis, demonstrating that temporal information can be retrieved using familiarity in certain instances. The final experimental Chapter 4 used fMRI to extend Chapter 3 and examine whether neural activity would be greater in regions associated with recollection during memory for context, while activity in familiarity-related regions would be higher during memory for time. Results revealed no support for these predictions with no regions linked to recollection showing greater context-related activity, and no regions previously linked to familiarity exhibiting increased activation as temporal information was retrieved. The results are discussed in relation to established recollection and familiarity frameworks and previous work examining the neural substrates supporting memory for time and context.
194

A behavioural and cognitive neuroscience investigation of deceptive communication

Hsu, Chun-Wei January 2018 (has links)
There is a rich literature on how people tell lies and detect them in others, but the underlying mechanisms are still poorly understood. The first aim of this thesis was to elucidate key cognitive and neural processes underlying cued (i.e., instructed) and uncued lies. The second aim, based on recent research suggesting a link between dishonesty and creativity, was to determine whether creative cognition contributes to deceptive communication. In a first behavioural study, performance on generating and detecting lies was measured in a socially interactive setting involving cued and uncued lies. Results of a multiple regression analysis showed that creativity predicted lying generation ability: more creative individuals were better liars than less creative people. In contrast, the ability to detect lies showed no association with creativity measures, suggesting that generating and detecting lies are distinct abilities. A second event-related potential (ERP) study investigated the neural mechanisms underlying the generation of uncued lies using a novel bluffing paradigm where participants lied at will. Results showed no stimulus-locked differences between uncued lies and truths, suggesting that decision processes leading to both required comparable cognitive resources. Once the uncued decision has been made, it requires strategic monitoring to keep track of the responses in order to maximize the gains regardless of whether the outcome is a lie or the truth as indexed by no response-locked differences between uncued lies and truths. Finally, parallel functional magnetic resonance imaging (fMRI) and ERP studies were conducted to determine the role of creativity in countermeasure use in a concealed information paradigm requiring cued lying. Results showed that countermeasures degraded the neural signatures of deception and more so for more creative individuals. This work advances understanding of the cognitive and neural mechanisms underlying deception as well as their dependence on individual differences in creative cognition.
195

Neural Correlates of Heart Rate Variability : Threat and Safety Perception

Frändén, Philip January 2018 (has links)
The connection between the heart and the brain was coined 150 years ago by Claude Bernard and has since then been an interesting topic of research. Scientists have for many years searched for biomarkers of stress and health to map the current status of the organism. Heart rate variability (HRV) has been presented as an emerging objective and promising marker to achieve just this. HRV refers to the beat-to-beat variations in heart rate (HR) and is thought to be a useful signal in understanding and providing valuable information of the autonomic nervous system (ANS). HRV has also been proposed as a marker of stress and health by sharing neural correlates and functions with several executive functions. This thesis identified several regions, including the ventromedial prefrontal cortex and the amygdala, in which significant associations across several studies were found between threat and safety perception, emotional regulation and HRV. This suggest that HRV may function as an index of the brain mechanism and structures that guide and govern adaptive functions and thus, provide researchers with valuable information regarding the stress and health of an organism. Two major theoretical frameworks, which articulate and explain the role of HRV as an indicator of individuals ability to adapt to environmental changes and cope under stress is presented. HRV can also be used in practice in several ways and a growing and promising field of application is HRV biofeedback.
196

Delineating the “Task-Irrelevant” Perceptual Learning Paradigm in the Context of Temporal Pairing, Auditory Pitch, and the Reading Disabled

January 2016 (has links)
abstract: Watanabe, Náñez, and Sasaki (2001) introduced a phenomenon they named “task-irrelevant perceptual learning” in which near-threshold stimuli that are not essential to a given task can be associatively learned when consistently and concurrently paired with the focal task. The present study employs a visual paired-shapes recognition task, using colored polygon targets as salient attended focal stimuli, with the goal of comparing the increases in perceptual sensitivity observed when near-threshold stimuli are temporally paired in varying manners with focal targets. Experiment 1 separated and compared the target-acquisition and target-recognition phases and revealed that sensitivity improved most when the near-threshold motion stimuli were paired with the focal target-acquisition phase. The parameters of sensitivity improvement were motion detection, critical flicker fusion threshold (CFFT), and letter-orientation decoding. Experiment 2 tested perceptual learning of near-threshold stimuli when they were offset from the focal stimuli presentation by ±350 ms. Performance improvements in motion detection, CFFT, and decoding were significantly greater for the group in which near-threshold motion was presented after the focal target. Experiment 3 showed that participants with reading difficulties who were exposed to focal target-acquisition training improved in sensitivity in all visual measures. Experiment 4 tested whether near-threshold stimulus learning occurred cross-modally with auditory stimuli and served as an active control for the first, second, and third experiments. Here, a tone was paired with all focal stimuli, but the tone was 1 Hz higher or lower when paired with the targeted focal stimuli associated with recognition. In Experiment 4, there was no improvement in visual sensitivity, but there was significant improvement in tone discrimination. Thus, this study, as a whole, confirms that pairing near-threshold stimuli with focal stimuli can improve performance in just tone discrimination, or in motion detection, CFFT, and letter decoding. Findings further support the thesis that the act of trying to remember a focal target also elicited greater associative learning of correlated near-threshold stimulus than the act of recognizing a target. Finally, these findings support that we have developed a visual learning paradigm that may potentially mitigate some of the visual deficits that are often experienced by the reading disabled. / Dissertation/Thesis / Doctoral Dissertation Psychology 2016
197

Heart rate variability : A possible measure of subjective wellbeing?

Boman, Kajsa January 2018 (has links)
Wellbeing and subjective wellbeing (SWB) has become some the most important goals of our time, both individually and societally. Thus, there is a need for reliable ways to measure SWB, as concerns regarding many current measures have been raised. Due to the interwoven nature of physiology and psychology, heart rate variability (HRV) has the potential to assess psychological processes in a physiological manner. HRV is an attractive measure since it is inexpensive, easy and non-invasive. Hence, the aim is to, from a cognitive neuroscientific standpoint, investigate whether HRV could serve as an objective measure to assess SWB. Most studies demonstrate associations between HRV and SWB, in particular between high frequency (HF)-HRV and positive affect (PA). However, the one study fully matching the theoretical framework only showed an inverse correlation between HRV and negative affect (NA). Plausibly implying that HRV does not serve as a reliable measure of SWB, but may be able to indicate inverse associations with NA, and possibly index certain aspect of SWB such as deactivated PA. The study of the relationship between HRV and SWB is still in its infancy and results are inconsistent. The lack of common standards regarding measurements, implementation details, and variable values, make results difficult to compare and generalize. Further standardizations and research are much needed before accurate conclusions can be drawn.
198

Empathy for pain and its modulating factors

Jones, Madeleine January 2018 (has links)
The present thesis deals with the concept of empathy for pain, its neurobiological underpinnings and modulations of the phenomenon. Empathy for pain is understood as the empathic response that occurs when recognising another in pain and entails at least the affective processes of actually felt pain in oneself. Cortical areas of importance for empathy for pain are the anterior insula and anterior cingulate cortex. Moreover, the phenomenon is correlated with high levels of empathy, as established by behavioural self-reports. Further, empathy for pain has been shown to be highly susceptible to modulatory factors giving rise to changes in the empathic response. Perceived fairness, perspective taking, intent and out-groups are all factors that can evoke change in the subsequent empathy for pain responses in humans. These modulatory factors provide insight into in- and out-group mechanisms. Cognitive strategies can regulate a diminished empathy for pain response, although further research is needed on how to cultivate and strengthen our ability to have empathy for another’s pain.
199

An Exploration of the Adaptive Functions of Dreams and Empirically-Based Methods of Dream Interpretation

Roberts, Isaac 01 January 2018 (has links)
This paper presents a meta-analysis of dream theory within psychology and neuroscience. The questions it attempts to answer are: what is the neuroscientific basis of dreaming? Why do dreams exist (do they have an adaptive function)? Could dreams possibly have no function? And, what is the best way to interpret a dream? The current analysis presents various theories relevant to each of these questions and compares their viability. It also briefly examines the origins of psychological thought on dreams and, towards the end, outlines the steps and empirical support for a well-regarded method of dream interpretation known as the cognitive experiential model. In the end, the analysis finds that a major likely cause of dreaming is the occurrence of different memory processes during REM sleep, whose activity likely also contributes to dream content. As for adaptive functions, the existing neuroscientific evidence suggests that we are almost certainly capable of learning during dreams and that learning may therefore be one of dreams’ primary adaptive functions. However, due to the scarcity of research on dreams, few of these conclusions can be drawn with overwhelming confidence. Lastly, in regards to dream interpretation, the cognitive experiential model seems to provides a framework for dream interpretation which clients and therapists alike find satisfying and useful.
200

Neuroticism related differences during porcessing of controlled congnitive tasks

Saylik, Rahmi January 2017 (has links)
It is suggested that neuroticism impairs cognitive performance mostly in difficult tasks i.e. WM tasks, but not so much in easier tasks. However, behavioural, and functional neuroanatomical correlates of detrimental effect of neuroticism in relation to central executive system (CES) during cognitive tasks particularly in multitasking still unknown. I aim at investigating behavioural and functional neuroanatomical correlates of single- and dual-task performance in high and low neurotics. The general hypothesis is that high neurotics will show a poorer performance on processing of cognitive tasks as compared to low neurotics. From a screened population, I select low neurotics (below 6) and high neurotics (over 16) on 24 item Eysenck Personality Questionnaire (EPQ) neuroticism scale. First empirical study was consisted of three standard WM tests. The result of this study showed that high neurotics had lower performance when the task heavily requires CES such as switching and inhibition. Next empirical studies were consisted of dual tasks based on PRP paradigm. In dual task studies, in addition to SOA manipulation SOA (0 and1000ms), task demand manipulated either by presentation of task order or task set maintenance. The results show that high neurotics considerably slower when SOA is short. Further, it has been observed dual task cost differences between high and low neurotics increase as the demand increase either by random tasks or task set maintenance as evident by lower processing efficiency in high neurotics. Also, high neurotics perceived higher stress level as the task demand increase. In the final study, I assessed brain activity by means of functional magnetic resonance imaging (fMRI) in low and high neurotics while they were performing a demanding dual-task and the less demanding component tasks as single-tasks. Imaging data showed that high neurotics showed less dual-task specific activation in lateral and medial prefrontal cortices. In conclusion, I conclude that high levels of neuroticism impair behavioural performance in demanding tasks with higher perceived stress level, and that this impairment is accompanied by reduced activation of the task-associated brain areas. Key words: Neuroticism, Personality, Multitasking, dual-task performance, prefrontal cortex attentional control theory, working memory.

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