Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 2003. / Includes bibliographical references.

Thesis (B.Sc.Hons.) -- University of Adelaide, Department of Psychology, 1972.

Thesis (Ph. D.)--UCLA, 2008. / Vita. Includes bibliographical references (leaves 124-125).

The primary somatosensory cortex (SI) and primary motor cortex (M1) receive somatosensory afferent input to influence motor hand circuitry and control. Much of the literature has investigated this relationship extensively using animal models. In contrast, much of these relationships and neural mechanisms are still not well understood in humans. The present work investigated homosynaptic and hetersynaptic protocol’s modulatory effects on SI and M1 sensorimotor circuitry. Experiment 1 used the homosynaptic protocol continuous theta-burst stimulation (cTBS) over SI and M1 and measured motor evoked potentials (MEP) and short-latency afferent inhibition (SAI). CTBS over M1 suppressed MEPs and did not alter SAI. In contrast, cTBS over SI facilitated MEPs and decreased median and digital nerve evoked SAI. Experiment 2 used the heterosynaptic protocol rapid-rate paired associative stimulation (rPAS) on SI and M1. SAI and MEPs were measured to investigate the sensorimotor changes following rPAS. Results indicated minimal decreases in SAI but increases in MEPs following SI rPAS. However, M1 rPAS lead to significant reductions in SAI and increased MEPs. The findings from this thesis highlight the selective modulation of sensorimotor circuitry through the use of various stimulation protocols. / Thesis / Master of Science in Kinesiology

My thesis focuses on describing novel functional connectivity properties of the sensorimotor system that are of potential interest in the field of brain-machine interface. In particular, I have investigated how the connectivity changes as a consequence of either pathologic conditions or spontaneous fluctuations of the brain's internal state. An ad-hoc electronic device has been developed to implement the appropriate experimental settings. First, the functional communication among sensorimotor primary nodes was investigated in multiple sclerosis patients afflicted by persistent fatigue. I selected this condition, for which there is no effective pharmacological treatment, since existing literature links this type of fatigue to the motor control system. In this study, electroencephalographic (EEG) and electromyographic (EMG) traces were acquired together with the pressure exerted on a bulb during an isometric hand grip. The results showed a higher frequency connection between central and peripheral nervous systems (CMC) and an overcorrection of the exerted movement in fatigued multiple sclerosis patients. In fact, even though any fatigue-dependent brain and muscular oscillatory activity alterations were absent, their connectivity worked at higher frequencies as fatigue increased, explaining 67% of the fatigue scale (MFIS) variance (p=.002). In other terms, the functional communication within the central-peripheral nervous systems, namely involving primary sensorimotor areas, was sensitive to tiny alterations in neural connectivity leading to fatigue, well before the appearance of impairments in single nodes of the network. The second study was about connectivity intended as propagation of information and studied in dependence on spontaneous fluctuations of the sensorimotor system triggered by an external stimulus. Knowledge of the propagation mechanisms and of their changes is essential to extract significant information from single trials. The EEG traces were acquired during transcranial magnetic stimulation (TMS) to yield to a deeper knowledge about the response to an external stimulation while the cortico-spinal system passes through different states. The results showed that spontaneous increases of the excitation of the node originating the transmission within the hand control network gave rise to dynamic recruitment patterns with opposite behaviors, weaker in homotopic and parietal circuits, stronger in frontal ones. As probed by TMS, this behavior indicates that the effective connectivity within bilateral circuits orchestrating hand control are dynamically modulated in time even in resting state. The third investigation assessed the plastic changes in the sensorimotor system after stroke induced by 3 months of robotic rehabilitation in chronic phase. A functional source extraction procedure was applied on the acquired EEG data, enabling the investigation of the functional connectivity between homologous areas in the resting state. The most significant result was that the clinical ameliorations were associated to a ‘normalization’ of the functional connectivity between homologous areas. In fact, the brain connectivity did not necessarily increase or decrease, but it settled within a ‘physiological’ range of connectivity. These studies strengthen our knowledge about the behavioral role of the functional connectivity among neuronal networks’ nodes, which will be essential in future developments of enhanced rehabilitative interventions, including brain-machine interfaces. The presented research also moves the definition of new indices of clinical state evaluation relevant for compensating interventions, a step forward.

No description available.

Thesis (Ed. Spec.)--University of Wisconsin--Stout, 2009. / Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

A human infant facing the blooming, buzzing confusion of the senses grows up to be an adult with common-sense knowledge of geometry; this knowledge then allows her to describe the shapes of objects, the layouts of places, and the relative locations of things naturally and effortlessly. In robotics, such knowledge is usually built in by a human designer who needs to solve complex engineering problems of sensor calibration and inference. In contrast, this dissertation presents a model for how autonomous agents can form an understanding of geometry the same way infants do: by learning from early unstructured sensorimotor experience. Through a framework called sensorimotor embedding, an agent reconstructs knowledge of its own sensor structure, the local geometry of the world, and the pose of objects within the world. The validity of this knowledge is demonstrated directly through Procrustes analysis and indirectly by using it to solve the mountain car task with different morphologies. The dissertation demonstrates how sensorimotor embedding can serve as a robust approach for acquiring geometric knowledge. / text

Thesis (Dip.App.Psych.) -- University of Adelaide, Dept. of Psychology, 1977.