Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 105-133). Available also in a digital version from Dissertation Abstracts.

Excitatory glutamatergic inputs from limbic regions such as the hippocampus and the basolateral amygdala (BLA), and dopaminergic inputs from the ventral tegmental area converge in the nucleus accumbens (NAc). It has been proposed that interactions between these glutamatergic and dopaminergic pathways play an important role in adaptive behaviors. The present thesis employed a multidisciplinary approach to study these interactions, with a specific emphasis on the importance of mesoaccumbens dopamine (DA) transmission, in order to obtain a better understanding of the neural mechanisms by which the NAc transforms signals from the temporal lobes into behavior. The experiments of Chapter 2 utilized extracellular single-unit recordings of individual NAc neurons in combination with electrochemical measures of DA efflux in the NAc. Recordings from NAc neurons which received input from the hippocampus but not the BLA revealed that increased efflux of mesoaccumbens DA, evoked by tetanic stimulation of the fimbria, potentiated hippocampal-evoked neural activity in these cells. These effects were mediated by both DA and NMDA receptors. Similar recordings from neurons which received converging input from both the hippocampus and the BLA revealed tetanic stimulation of the fimbria again potentiated hippocampal evoked spiking activity, while concurrently suppressing BLA-evoked spiking activity in the same neurons. The suppression of BLA-evoked spiking activity was activity-dependent, and was mediated by both D, and adenosine A, receptors. Chapter 3 showed that random foraging on a radial-arm maze, which is dependent on a neural circuit linking the hippocampus to the NAc, was correlated with an increase in mesoaccumbens DA extracellular levels, as measured with microdialysis. In Chapter 4, pharmacological blockade of DA or NMDA receptors in the NAc, or selective disruption of dopaminergic modulation of ventral subicular inputs to the NAc (using an asymmetrical infusion procedure) significantly disrupted random foraging. These effects were mediated by the Dl receptor. In Chapter 5, the present data are integrated with previous research to formulate a model of ventral striatal function. It is proposed that the NAc mediates behavior through distinct patterns of activity and inactivity driven by excitatory limbic input projecting to different groups of neural ensembles. Mesoaccumbens DA transmission plays an essential role in regulating the synchrony ensemble activity, augmenting activity in one ensemble while suppressing activity in another. It is argued that the modulatory effects of DA appears to be essential when an organism must switch from one form of adaptive behavior to another in response to a constantly changing environment.

Thesis (M.A.)--University of Delaware, 2008. / Principal faculty advisor: Jeffrey B. Rosen, Dept. of Psychology. Includes bibliographical references.

Thesis (Ph. D. in Molecular Physiology and Biophysics)--Vanderbilt University, Aug. 2009. / Title from title screen. Includes bibliographical references.

Excitatory glutamatergic inputs from limbic regions such as the hippocampus and the basolateral amygdala (BLA), and dopaminergic inputs from the ventral tegmental area converge in the nucleus accumbens (NAc). It has been proposed that interactions between these glutamatergic and dopaminergic pathways play an important role in adaptive behaviors. The present thesis employed a multidisciplinary approach to study these interactions, with a specific emphasis on the importance of mesoaccumbens dopamine (DA) transmission, in order to obtain a better understanding of the neural mechanisms by which the NAc transforms signals from the temporal lobes into behavior. The experiments of Chapter 2 utilized extracellular single-unit recordings of individual NAc neurons in combination with electrochemical measures of DA efflux in the NAc. Recordings from NAc neurons which received input from the hippocampus but not the BLA revealed that increased efflux of mesoaccumbens DA, evoked by tetanic stimulation of the fimbria, potentiated hippocampal-evoked neural activity in these cells. These effects were mediated by both DA and NMDA receptors. Similar recordings from neurons which received converging input from both the hippocampus and the BLA revealed tetanic stimulation of the fimbria again potentiated hippocampal evoked spiking activity, while concurrently suppressing BLA-evoked spiking activity in the same neurons. The suppression of BLA-evoked spiking activity was activity-dependent, and was mediated by both D, and adenosine A, receptors. Chapter 3 showed that random foraging on a radial-arm maze, which is dependent on a neural circuit linking the hippocampus to the NAc, was correlated with an increase in mesoaccumbens DA extracellular levels, as measured with microdialysis. In Chapter 4, pharmacological blockade of DA or NMDA receptors in the NAc, or selective disruption of dopaminergic modulation of ventral subicular inputs to the NAc (using an asymmetrical infusion procedure) significantly disrupted random foraging. These effects were mediated by the Dl receptor. In Chapter 5, the present data are integrated with previous research to formulate a model of ventral striatal function. It is proposed that the NAc mediates behavior through distinct patterns of activity and inactivity driven by excitatory limbic input projecting to different groups of neural ensembles. Mesoaccumbens DA transmission plays an essential role in regulating the synchrony ensemble activity, augmenting activity in one ensemble while suppressing activity in another. It is argued that the modulatory effects of DA appears to be essential when an organism must switch from one form of adaptive behavior to another in response to a constantly changing environment. / Arts, Faculty of / Psychology, Department of / Graduate

Decades of research have shown long-term effects of early caregiving adversity on stress physiology and limbic brain regions, two key biological systems that are implicated in risk for internalizing disorders. Although stress physiology and limbic brain structure undergo significant maturational change during childhood and adolescence, and reciprocally influence each other, the effects of early caregiving adversity on these developmental processes is not well understood. In the current study, we used an accelerated longitudinal design to assess the development of stress physiology, amygdala, and hippocampal volume following early institutional care. Previously Institutionalized (PI; N = 93) and comparison (COMP; N = 161) youth (ages 4-20 years old) completed 1-3 waves of data collection, each spaced approximately 2 years apart, for diurnal cortisol (N = 239, providing a total of 380 diurnal datasets), structural MRI (N = 156, providing a total of 306 scans) and parent-reported internalizing symptoms (N = 133, providing a total of 227 time points). We observed a developmental shift in morning cortisol in the PI group, with blunted levels in childhood and heightened levels in late adolescence. PI history was associated with reduced hippocampal volume and reduced growth of the amygdala, resulting in smaller volumes by adolescence. Results also suggested feed-forward brain-to-hormone mechanisms, such that both amygdala and hippocampal volumes were prospectively associated with morning cortisol levels two years later. Finally, amygdala and hippocampal volumes were independently associated with internalizing scores across the entire sample. These results indicate that adversity-related physiological and neural phenotypes are not stationary during development but instead exhibit dynamic and interdependent changes from early childhood to early adulthood.

Charles University of Prague Faculty of Pharmacy in Hradec Králové Department of Biological and Medicinal Sciences Student: Bc. Veronika Hončová Supervisor: Doc. MUDr. Josef Herink, DrSc. Consultant: MUDr. Jela Hrnčiarová Title: Signs of the temporolimbic dysfunction in gamblers Background: The aim of this thesis was to determine whether pathological gamblers exhibit symptoms related to epileptic spectrum disorder. Methods: To investigate, symptoms of the temporolimbic dysfunction were examined by means of the structured questionnaires CPSI (Complex Partial Symptoms Inventory) and LSCL-33 (Limbic System Checklist-33). Mann-Whitney U test and Spearman's correlation coefficient were used for statistical evaluation. Results: The mean score in the questionnaire CPSI of gamblers was 38,9 points, which is an abnormal score. With the questionnaire LSCL-33, the mean score of 21,5 points, corresponds to suspected findings. From the mean results it can be concluded that pathological gamblers may have a higher incidence of the symptoms of the temporolimbic dysfunction. When comparing the groups of gamblers with smokers, it was evaluated that in the questionnaire CPSI was a statistically significant difference between the appearances of symptoms of epileptic spectrum disorder, while it was not in the...

This dissertation discusses an implementation of a design, control and motion planning for a novel extendable modular redundant robotic manipulator in space constraints, which robots may encounter for completing required tasks in small and constrained environment. The design intent is to facilitate the movement of the proposed robotic manipulator in constrained environments, such as rubble piles. The proposed robotic manipulator with multi Degree of Freedom (m-DOF) links is capable of elongating by 25% of its nominal length. In this context, a design optimization problem with multiple objectives is also considered. In order to identify the benefits of the proposed design strategy, the reachable workspace of the proposed manipulator is compared with that of the Jet Propulsion Laboratory (JPL) serpentine robot. The simulation results show that the proposed manipulator has a relatively efficient reachable workspace, needed in constrained environments. The singularity and manipulability of the designed manipulator are investigated. In this study, we investigate the number of links that produces the optimal design architecture of the proposed robotic manipulator. The total number of links decided by a design optimization can be useful distinction in practice. Also, we have considered a novel robust bio-inspired Sliding Mode Control (SMC) to achieve favorable tracking performance for a class of robotic manipulators with uncertainties. To eliminate the chattering problem of the conventional sliding mode control, we apply the Brain Emotional Learning Based Intelligent Control (BELBIC) to adaptively adjust the control input law in sliding mode control. The on-line computed parameters achieve favorable system robustness in process of parameter uncertainties and external disturbances. The simulation results demonstrate that our control strategy is effective in tracking high speed trajectories with less chattering, as compared to the conventional sliding mode control. The learning process of BLS is shown to enhance the performance of a new robust controller. Lastly, we consider the potential field methodology to generate a desired trajectory in small and constrained environments. Also, Obstacle Collision Avoidance (OCA) is applied to obtain an inverse kinematic solution of a redundant robotic manipulator.

Psychopathy is a severe personality disorder associated with a range of affective, interpersonal, and behavioural abnormalities. Evidence suggests that psychopaths show marked deficits in processing emotional information, although it is unclear whether they also show more general deficits in error monitoring, attention allocation and response control. It is also unclear whether any variation in neurophysiological performance is also reflected in subclinical populations. In this thesis, event-related potentials (ERPs) were used to examine these issues and involved two separate samples. The first included incarcerated offenders with a range of scores on the Hare Psychopathy Checklist –Revised (PCL-R) and non-offender (staff) controls. The second included a large group of healthy undergraduate males with a full range on scores on the Self-Report Psychopathy Scale (SRP-III). Error monitoring was examined in both samples using a standard letter-flanker task and a modified version of the task in which faces with angry or fearful expressions were used instead of the usual letter stimuli. In general, psychopathy in both samples was associated with attenuated ERN amplitudes on the face flanker task only. Source modeling of the ERN indicated that, while the ERN is generally modeled as having a dipole in the ACC, the psychopath group showed no evidence of ACC activity in this region in conjunction with face-flanker errors. These data suggest that the affect-based neurophysiological deficits associated with psychopathy in the clinical range are observed in a graduated fashion among subclinical samples. Inhibitory control processes were also examined in the incarcerated group using the inhibitory N2 and anteriorized P3 as indices of inhibitory processes evident in correctly withholding prepotent response tendencies on a Go-NoGo task. Despite the common assumption that poor inhibitory control is a central aspect of psychopathy, there was no sign that those at higher levels of psychopathy showed any inhibitory control problems and they produced a robust NoGo N2 and P3. In fact, there were signs that the incarcerated offenders who were low on psychopathy were more likely to produce diminished inhibitory-related components. Finally, years of controversy regarding attention allocation deficits in psychopathy was addressed by collecting standard P3 components during a traditional visual oddball task in the university sample. Behavioural response and P3 amplitudes were unrelated to psychopathy. However, consistent with data from incarcerated samples, higher scores on psychopathy were associated with larger amplitude P2 and N5 responses to target relative to nontarget stimuli, again suggesting some continuity with respect to a distinct, although not necessarily deficient, attentional style at subclinical levels of psychopathy. In general, across these four data sets, the only clear evidence of impaired processing involved a reduced error-monitoring response during the face-flanker task when emotional stimuli formed the basis of the required discrimination and this reduced response was found to vary with the degree of psychopathy even within a subclinical range. These findings support a model of psychopathy involving limbic and paralimbic structures rather than a general reduction in neural function affecting error monitoring, attention allocation and response control.

Psychopathy is a severe personality disorder associated with a range of affective, interpersonal, and behavioural abnormalities. Evidence suggests that psychopaths show marked deficits in processing emotional information, although it is unclear whether they also show more general deficits in error monitoring, attention allocation and response control. It is also unclear whether any variation in neurophysiological performance is also reflected in subclinical populations. In this thesis, event-related potentials (ERPs) were used to examine these issues and involved two separate samples. The first included incarcerated offenders with a range of scores on the Hare Psychopathy Checklist –Revised (PCL-R) and non-offender (staff) controls. The second included a large group of healthy undergraduate males with a full range on scores on the Self-Report Psychopathy Scale (SRP-III). Error monitoring was examined in both samples using a standard letter-flanker task and a modified version of the task in which faces with angry or fearful expressions were used instead of the usual letter stimuli. In general, psychopathy in both samples was associated with attenuated ERN amplitudes on the face flanker task only. Source modeling of the ERN indicated that, while the ERN is generally modeled as having a dipole in the ACC, the psychopath group showed no evidence of ACC activity in this region in conjunction with face-flanker errors. These data suggest that the affect-based neurophysiological deficits associated with psychopathy in the clinical range are observed in a graduated fashion among subclinical samples. Inhibitory control processes were also examined in the incarcerated group using the inhibitory N2 and anteriorized P3 as indices of inhibitory processes evident in correctly withholding prepotent response tendencies on a Go-NoGo task. Despite the common assumption that poor inhibitory control is a central aspect of psychopathy, there was no sign that those at higher levels of psychopathy showed any inhibitory control problems and they produced a robust NoGo N2 and P3. In fact, there were signs that the incarcerated offenders who were low on psychopathy were more likely to produce diminished inhibitory-related components. Finally, years of controversy regarding attention allocation deficits in psychopathy was addressed by collecting standard P3 components during a traditional visual oddball task in the university sample. Behavioural response and P3 amplitudes were unrelated to psychopathy. However, consistent with data from incarcerated samples, higher scores on psychopathy were associated with larger amplitude P2 and N5 responses to target relative to nontarget stimuli, again suggesting some continuity with respect to a distinct, although not necessarily deficient, attentional style at subclinical levels of psychopathy. In general, across these four data sets, the only clear evidence of impaired processing involved a reduced error-monitoring response during the face-flanker task when emotional stimuli formed the basis of the required discrimination and this reduced response was found to vary with the degree of psychopathy even within a subclinical range. These findings support a model of psychopathy involving limbic and paralimbic structures rather than a general reduction in neural function affecting error monitoring, attention allocation and response control.