This thesis focuses on tactile perception and aims at a comprehensive analysis of its characteristics over the time-course of various goal-directed movements. Tactile perception is assessed by means of discrimination and detection paradigms, as well as event-related potentials (ERPs). The main question investigated throughout the thesis is: ‘What changes in tactile perception, if any, take place over the time course of a goal-directed movement?’ In Chapter 2, the mechanisms related to such identified changes are examined: a facilitatory one – attention, and an inhibitory one – suppression. The experiment in Chapter 3 tests, at a brain level, amongst several explanations of the experimental results outlined in Chapter 2: timing-based, effector-based, and modality-based attentional/suppressive influences. In Chapter 4, other naturalistic movements are investigated (i.e., the movements involved in juggling and throwing/catching a basketball). The results indicate a lack of facilitation in the processing of tactile information during the preparatory phase of the movement. Furthermore, differential changes are identified in tactile perception over the execution phase of the movement: At a behavioural level, tactile sensitivity significantly declines over the execution phase of the movement (though the detection of incoming tactile stimulation is enhanced), while at a neuronal level the same period exhibits significantly enhanced responses to somatosensory stimulation. The experiments reported here thus bring evidence in favour of a dissociation between detecting and discriminating what is felt while moving. These results suggest that the quality of what is felt while moving may not be important for movement and, at the same time, that different pathways in the brain may be responsible for detecting and discriminating what is felt over the time course of a goal-directed movement. Based on these findings, in Chapter 5, the implications of these results are discussed and directions for further research are outlined.

It is well established that anticipation of the arrival of an expected stimulus is accompanied by rich ongoing oscillatory neurodynamics, which span and link large areas of cortex. An intriguing possibility is that these dynamic interactions may convey knowledge that is embodied by large-scale neurocognitive networks from higher level regions of multi-model cortex to lower level primary sensory areas. In the current study, using autoregressive spectral analysis, we establish that during the anticipatory phase of a visual discrimination task there are rich patterns of coherent interaction between various levels of the ventral visual hierarchy across the frequency spectrum of 8 - 90 Hz. Using spectral Granger causality we determined that a subset of these interactions carry beta frequency (14 - 30 Hz) top-down influences from higher level visual regions V4 and TEO to primary visual cortex. We investigated the functional significance of these top-down interactions by correlating the magnitude of the anticipatory signals with the amplitude of the visual evoked potential that was elicited by stimulus processing. We found that in one third of the extrastriate-striate pairs, tested in three monkeys, the amplitude of the visual evoked response is well predicted by the magnitude of pre-stimulus coherent top-down anticipatory influences. To investigate the dynamics of the coherent and topdown Granger causal interactions, we analyzed the relationship between coherence and top-down Granger causality with stimulus onset asynchrony. This analysis revealed that in an abundance of cases the magnitudes of the coherent interactions and top-down directional influences scaled with the length of time that had elapsed before stimulus onset. / Together these results reveal a complex network of coherent and top-down directional interactions that predict the amplitude of early components of the visual evoked potential in primary visual cortex and vary in strength on the basis of the length of the stimulus onset. / by Craig G. Richter. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

Bering and colleagues (2004, 2005) reported that the expectation that conscious mental states cease with the onset of death (discontinuity reasoning) emerges developmentally, and discontinuity reasoning for some states (emotions, desire, epistemic) remains lower than for others (psychobiological, perceptual). Cormier (2005) reported very similar findings for the context of sleep and proposed a modular explanation of these effects (“intentional persistence”) and suggested that intentional persistence represents an evolved adaptation designed to maintain vigilance and behavioral preparedness while in the presence of animals of ambiguous agency status (e.g., death, sleep, hibernation, feigned death). The current study extended this line of research to realistic animal characters. Although results revealed patterns of discontinuity reasoning and intentional persistence that were consistent with those of previous studies, the prediction that intentional persistence would be more pronounced for predators was not fulfilled. A newly proposed evolutionary product, “Cooptation,” was introduced to further explain the results. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

This study examined the topography of prefrontal molds of human endocasts using three-dimensional laser scanning and geographic information systems (GIS) in order to carry out intra-species comparisons. Overall brain topography can indicate when major reorganizational shifts in brain structure happened in our evolutionalry history, and these shifts may indicate major shifts in cognition and behavior. Endocasts are one of the sole sources of information about extinct hominin brains ; they reproduce details of the brain's external morphology. Analysis of endocast morphology has never been done using GIS methodology. The use of GIS helps to overcome previous obstacles in regards to endocast analysis. Since this methodology is new, this research focuses on only one species, Homo sapiens and the area of focus is narrowed to the frontal lobe, specifically Broca's cap. This area is associated with speech in humans and is therefore of evolutionary significance. The variability in lateralization of this feature was quantified. / by Melissa Boas. / Thesis (M.A.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

A hallmark of intelligence in humans and other animals is the ability to engage in complex behaviors geared towards achieving far-removed goals. Such behavior relies on a set of diverse and sophisticated mental processes that are collectively referred to as cognitive or executive in nature. The prefrontal cortex (PFC) has long been considered the primary neural locus for such processes. From humans down to rodents, damage to the PFC has been shown to impair cognition and executive function. In neuropsychiatric disorders such as schizophrenia, dysfunction of the PFC has been strongly linked to cognitive dysfunction. PFC functioning however, necessarily relies on interactions within and between networks of interconnected neurons. Across species, the PFC has been anatomically defined as the region of cortex reciprocally connected with the mediodorsal thalamus (MD), a definition that suggests PFC functioning cannot be divorced from that of its main thalamic counterpart. Indeed, an increasing number of studies have demonstrated the involvement of MD in cognitive behaviors. Schizophrenia patients performing cognitive tasks also exhibit decreased MD activity, with growing evidence for decreased functional connectivity with the PFC. The studies presented here seek to build on this literature using the mouse as a model organism. Taking advantage of recent tools for temporally- and spatially-restricted manipulations of neural activity we show that a relatively mild and reversible decrease in MD activity is capable of impairing two cognitive behaviors classically shown to be PFC-dependent – behavioral flexibility and working memory. Simultaneously recording MD and PFC activity while mice perform a spatial working memory task, we show task modulations of synchronous MD-PFC activity that are disrupted by a primary decrease in MD activity. Following up on this finding using pathway-specific manipulations of MD-to-PFC and PFC-to-MD neural connections, we provide behavioral and neurophysiological evidence that these circuits serve as distinct neural substrates for working memory maintenance and retrieval. Together, these findings provide causal evidence in support of an association between thalamo-prefrontal dysfunction and cognitive impairment, and may enable the development of more selective therapeutic strategies for cognitive disorders such as schizophrenia.

The privacy paradox is a phenomenon whereby individuals continue to disclose their personal information, contrary to their claim of concerns for the privacy of their personal information. This study investigated the privacy paradox to better understand individuals' decisions to disclose or withhold their personal information. The study argued that individuals’ decisions are based on a cognitive disposition, which involves both rational and emotional mental processes. While the extended privacy calculus model was used as the theoretical basis for the study, the findings of cognitive neuroscience was applied to it to address its limitation in assuming individuals are purely rational decision-makers. Three within-subjects experiments were conducted whereby each subject participated in all three experiments as if it were one. Experiment 1 captured the neural correlates of mental processes involved in privacy-related decisions, while experiment 2 and 3 were factorial-design experiments used for testing the relationship of neural correlates in predicting privacy concerns and personal information disclosure. The findings of this study indicated that at least one neural correlate of every mental process involved in privacy-related decisions significantly influenced personal information disclosure, except for uncertainty. However, there were no significant relationships between mental processes and privacy concerns, except Brodmann’s Area 13, a neural correlate of distrust. This relationship, however, had a positive relationship with privacy concerns, opposite to what was hypothesized. Furthermore, interaction effects indicated that individuals put more emphasis on negative perceptions in privacy-related situations. This study contributed to the information privacy field by supporting the argument that individuals’ privacy-related decisions are both rational and emotional. Specifically, the privacy paradox cannot be explained through solely rational cost-benefit analysis or through an examination of individuals’ emotions alone.

Psychotic symptoms are prevalent in a wide variety of psychiatric and neurological disorders. Yet, despite decades of research, the neurobiological mechanisms via which these symptoms come to manifest themselves remain to be elucidated. I argue in this thesis that using a mechanistic approach towards understanding psychosis that borrows heavily from the predictive coding framework, can help us understand the relationship between neurobiology and symptomology. In the first results chapter I present new data on a biomarker that has often been cited in relation to psychotic disorders, which is glutamate levels in the anterior cingulate cortex (ACC), as measured with magnetic resonance spectroscopy. In this chapter I aimed to replicate previous results that show differences in glutamate levels in psychosis and health. However, no statistically significant group differences and correlations with symptomology were found. In order to elucidate the potential mechanism underlying glutamate changes in the anterior cingulate cortex in psychosis, I tested whether a pharmacological challenge of Bromocriptine or Sulpiride altered glutamate levels in the anterior cingulate cortex. However, no significant group differences were found, between medication groups. In the second results chapter I aimed to address a long-standing question in the field of computational psychiatry, which is whether prior expectations have a stronger or weaker influence on inference in psychosis. I go on to show that this depends on the origin of the prior expectation and disease stage. That is, cognitive priors are stronger in first episode psychosis but not in people at risk for psychosis, whereas perceptual priors seem to be weakened in individuals at risk for psychosis compared to healthy individuals and individuals with first episode psychosis. Furthermore, there is some evidence that these alterations are correlated with glutamate levels. In the third results chapter I aimed to elucidate the nature of reward prediction error aberrancies in chronic schizophrenia. There has been some evidence suggesting that schizophrenia is associated with aberrant coding of reward prediction errors during reinforcement learning. However it is unclear whether these aberrancies are related to disease years and medication use. Here I provide evidence for a small but significant alteration in the coding of reward prediction errors that is correlated with medication use. In the fourth results chapter I aimed to study the influence of uncertainty on the coding of unsigned prediction errors during learning. It has been hypothesized by predictive coding theorists that dopamine plays a role in the precision-weighting of unsigned prediction error. This theory is of particular relevance to psychosis research, as this might provide a mechanism via which dopamine aberrancies, might lead to psychotic symptoms. I found that blocking dopamine using Sulpiride abolishes precision-weighting of unsigned prediction error, providing evidence for a dopamine mediated precision-weighting mechanism. In the fifth results chapter I aimed to extend this research into early psychosis, to elucidate whether psychosis is indeed associated with a failure to precision-weight prediction error. I found that first episode psychosis is indeed associated with a failure to precision-weight prediction errors, an effect that is explained by the experience of positive symptoms. In the sixth results chapter I explore whether the degree of precision-weighting of unsigned prediction errors is correlated with glutamate levels in the anterior cingulate cortex. Such a correlation might be plausible given that psychosis has been associated with both. However, I did not find such a relationship, even in a sample of 137 individuals. Thus I concluded that anterior cingulate glutamate levels might be more related to non-positive symptoms associated with psychotic disorders. In summary, a mechanistic approach towards understanding psychosis can give us valuable insights into the disease mechanisms at play. I have shown here that the influence of expectations on perception is different across disease stage in psychosis. Furthermore, aberrancies in prediction error mechanisms might explain positive symptoms in psychosis, a process likely mediated by dopaminergic mechanisms, whereas evidence for glutamatergic mediation remains absent.

In the current study 24 younger adults and 24 older adults haptically discriminated natural 3-D shapes (bell peppers, Capsicum annuum) using unimanual (one hand used to explore two objects) and bimanual (both hands used, but each hand explored separate objects) successive exploration. Haptic exploration using just one hand requires somatosensory processing in only one cerebral hemisphere (the hemisphere contralateral to the hand being used), while bimanual haptic exploration requires somatosensory processing in both hemispheres. Previous studies related to curvature/shape perception have found either an advantage for unimanual exploration over bimanual exploration or no difference between the two conditions. In contrast to the results of previous studies that found an advantage for unimanual exploration, the current study found that unimanual and bimanual haptic exploration produced equivalent shape discrimination performance. The current results also document a significant effect of age on haptic shape discrimination: older adults exhibited moderately reduced shape discrimination performance compared to younger adults, regardless of the mode of exploration (unimanual or bimanual).

The purpose of this thesis is to explore a thought-provoking consequence of the functionalist theory of mind. Given the current organizational structure of Earth and field theories of consciousness in neuroscience, Earth is probably conscious. The argument is explored through an examination of the current organizational structure of Earth and field theories of consciousness in neuroscience, which leads to the conclusion that Earth is conscious. Various theories of mind have been proposed by neuroscientists and philosophers alike in an attempt to qualify what consciousness is and what provides the basis for consciousness to occur. Support, in the form of data and information, for this thesis was found through reviews of philosophic and neuroscientific literature. Using a functionalist argument and field theories of consciousness, I argue for the possibility of Earth’s consciousness due to its organization. Based on the likelihood of human consciousness being spatially distributed, I illustrate how Earth’s organization is sufficiently similar. However, there is controversy surrounding functionalist theories of mind. This is detailed with Ned Block’s (1978) objection to functionalism, the Chinese Nation thought experiment. I place this objection in conversation with Paul and Patricia Churchland’s (1981) work on inverted qualia, absent qualia, and the method to identify systems with and without qualia. A further objection to my conclusion is explored with Kammerer’s (2015) Sophisticated Anti-Nesting Principle is addressed. Finally, this thesis draws some inspiration from Eric Schwitzgebel’s (2014) paper “If Materialism is True, the United States is Probably Conscious,” but the conclusion is projected to a larger scale, resulting in implications for morality, politics, and theories of mind.

This thesis is concerned with the computational modelling and simulation of physiological structures and cognitive functions of brains through the use of artificial neural nets. While the structures of these models are loosely related to neurons and physiological structures observed in brains, the extent to which we can accept claims about how neurons and brains really function based on such models depends largely on judgments about the fitness of (virtual) computer experiments as empirical evidence. The thesis examines the computational foundations of neural models, neural nets, and some computational models of higher cognitive functions in terms of their ability to provide empirical support for theories within the framework of Parallel Distributed Processing (PDP). Models of higher cognitive functions in this framework are often presented in forms that hybridise top-down (e.g. employing terminology from Psychology or Linguistics) and bottom-up (neurons and neural circuits) approaches to cognition. In this thesis I argue that the use of terminology from either approach can blind us to the highly theory-laden nature of the models, and that this tends to produce overly optimistic evaluations of the empirical value of computer experiments on these models. I argue, further, that some classes of computational models and simulations based on methodologies that hybridise top-down and bottom-up approaches are ill-designed. Consequently, many of the theoretical claims based on these models cannot be supported by experiments with such models. As a result, I question the effectiveness of computer experiments with artificial neural nets as an empirical technique for cognitive modelling.