In this thesis we pitted two views of action selection. On the one hand, a traditional view suggesting that action selection emerges from a sequential process whereby perception, cognition and action proceed serially and are subtended by distinct brain areas. On the other hand, an ecological view (formalized in the affordance competition hypothesis) advocating that action selection stems from the parallel implementation of potential action plans. In parallel, the competition between these action plans would be biased by relevant task factors. We first addressed the issue of the temporal dynamics of action selection processes in Chapter 2. We built a reaching task design that crucially gave equal opportunities for serial and parallel processing of cognitive and motor processes to occur. In our study, we first cued participants with probabilities associated to upcoming potential reaches. After several hundreds of milliseconds, participants were given a deterministic go signal indicating which target to reach for. They had to reach for the signaled target as fast as possible. Importantly, our design tries to cope with the biases involved in previous reaching tasks, allowing for a much more informative way to tackle the issue of serial versus parallel processing in action selection. We show that effects of action probability are not only present in the initiation time (i.e. the time it takes to initiate the movement), but crucially also in the movement time (i.e. the time interval between movement initiation and target reaching). Furthermore, an analysis of the movement trajectories showed that reach probability influenced the trajectories according to the predicted pattern. Thus, these results back up a system where cognitive and motor processes continuously interact with one another to come up with a decision. After clarifying the temporal dynamics, we concentrate our efforts on exposing the neural architecture of processes subtending action selection in Chapter 3. In a two-choice button press task, participants were first cued with predictive information regarding upcoming button presses. Crucially, we experimentally manipulated the amount of information in favor of specific button presses whilst adopting a design as similar as possible to those used in monkey neurophysiology (e.g. Cisek & Kalaska, 2005). Using fMRI, our results showed that as information in favor a button press increases, so does activity in the contralateral primary motor cortex, while activity in the ipsilateral primary motor cortex decreases. Moreover, we observed that primary motor regions are more tightly coupled with fronto-parietal areas in a condition involving a decision compared with a situation not implicating a decision between two button presses. Our results are compatible with an account predicting that decision-making emerges from motor areas, and therefore suggest that the architecture presented in the affordance competition hypothesis is not only valid in monkeys but also humans. In Chapter 4, we combine the findings acquired in the studies of chapter 2 and 3 with recent neurophysiological insights to develop a neuro-computational model capable of grasping the continuous interaction between cognitive and motor processes, responsible for the behavioral pattern in reach selection tasks. Our model functions on the principles of cascade forward models whereby activation at one stage of processing systematically spills to the next one, thereby substantially blurring the boundaries between perceptive, cognitive and motor processes. Contrary to most computational models confining action selection processes prior to action execution, our model allows for these processes to leak into action execution. Moreover, the threshold for action execution is not fixed, but rather dynamic and crucially depends on the activity pattern of the model’s primary motor neurons. We propose that the modification of the threshold is governed by the subthalamic nucleus, receiving direct input signals from the primary motor cortex and in turn imposing a dynamical brake on action execution. By including this dynamical threshold, our model has the advantage that it can release movement execution either rapidly or slowly depending on the context. Our model accounts not only for initiation times, but also movement times in reaching task studies. Furthermore, it can grasp the qualitative pattern of movement trajectories. This study suggests that to explain unfolding actions a classical fixed threshold is not sufficient, but rather an execution threshold level that is continuously being updated depending on the context is required. / Doctorat en Sciences psychologiques et de l'éducation / info:eu-repo/semantics/nonPublished

In 1981, a number of reports of death from immune system failure began to cause alarm in medical circles. The Human Immunodeficiency Virus (HIV) was identified as the cause of a condition known as Acquired Immune Deficiency Syndrome (AIDS). To date, there is no cure for AIDS, and as a result it is perceived as the deadliest medical condition of the century. While intensive research remains focused on development of a vaccine, there has been a strong move toward a more preventative approach that is holistic in nature, and encompasses behavioural and social components as being of equal importance. Going hand in hand with HIV/AIDS are Sexually Transmitted Infections (STIs). STIs are increasing around the world and in South Africa at a remarkable rate. Like HIV/AIDS, STIs are also transmitted during sex, more specifically through body contact during sex. Research has identified adolescents as a group that is particularly vulnerable to HIV and STI infection. Life-skills programmes use experiential learning to engage learners and are particularly popular because they empower individuals to make responsible, well thought out decisions based on well developed values and beliefs. There are however, various variables and agents that impact upon the success of HIV/AIDS and STI education. It is therefore suitable to adopt a biopsychosocial approach to underlie a HIV/AIDS and STI life-skills programme. Health models, such as the AIDS Risk Reduction Model, based on this approach should take into consideration important psychological variables to cope with changes in behaviour, as well as prepatory behaviours inclined towards preventing risky behaviour. The Ubuntu Education Fund is a non-government, international organisation that offered a life skills programme in HIV/AIDS, STIs, Rape and Child Abuse to learners in Grades 6 - 9. This study focused on HIV/AIDS and STIs. The sample size was 260 learners from the Nelson Mandela Metropolitan Region. A quasiexperimental one group pre-and post-test design was used to determine if there was a difference between the knowledge of these learners pre- and post- the life skills programme. The results of the study indicate that there was a small increase in knowledge after the life-skills programme intervention. In some schools there was even a decrease in knowledge. This study suggests that the life-skills programme was flawed and that it needs to be reviewed. The implications of these findings are discussed with suggestions for future interventions.

abstract: Stroke is a debilitating disorder and 75% of individuals with stroke (iwS) have upper extremity deficits. IwS are prescribed therapies to enhance upper-extremity mobility, but current most effective therapies have minimum requirements that the individuals with severe impairment do not meet. Thus, there is a need to enhance the therapies. Recent studies have shown that StartReact -the involuntary release of a planned movement, triggered by a startling stimulus (e.g., loud sound)- elicits faster and larger muscle activation in iwS compared to voluntary-initiated movement. However, StartReact has been only cursorily studied to date and there are some gaps in the StartReact knowledge. Previous studies have only evaluated StartReact on single-jointed movements in iwS, ignoring more functional tasks. IwS usually have abnormal flexor activity during extension tasks and abnormal muscle synergy especially during multi-jointed tasks; therefore, it is unknown 1) if more complex multi-jointed reach movements are susceptible to StartReact, and 2) if StartReact multi-jointed movements will be enhanced in the same way as single-jointed movements in iwS. In addition, previous studies showed that individuals with severe stroke, especially those with higher spasticity, experienced higher abnormal flexor muscle activation during StartReact trials. However, there is no study evaluating the impact of this elevated abnormal flexor activity on movement, muscle activation and muscle synergy alterations during voluntary-initiated movements after exposure to StartReact. This dissertation evaluates StartReact and the voluntary trials before and after exposure to StartReact during a point-to-point multi-jointed reach task to three different targets covering a large workspace. The results show that multi-jointed reach tasks are susceptible to StartReact in iwS and the distance, muscle and movement onset speed, and muscle activations percentages and amplitude increase during StartReact trials. In addition, the distance, accuracy, muscle and movement onsets speeds, and muscle synergy similarity indices to the norm synergies increase during the voluntary-initiated trials after exposure to StartReact. Overall, this dissertation shows that exposure to StartReact did not impair voluntary-initiated movement and muscle synergy, but even improved them. Therefore, this study suggests that StartReact is safe for more investigations in training studies and therapy. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2020

Orientador: Eliane Mauerberg de Castro / Banca: Heloisa Gagheggi Ravanini Gardon Gagliardo / Banca: José Angelo Barela / Resumo: A perseveração motora tem sido recentemente usada para interpretar a canônica tarefa "A não B" de Piaget. Nesta tarefa, as crianças observam o experimentador esconde um brinquedo em uma localização "A", um atraso é imposto, e então a criança é encorajada a alcançar. Para as tentativas em A, as crianças tipicamente alcançam para A, onde o objeto foi escondido. Depois de esconder várias vezes e alcançar sucessivamente para A, o experimentador esconde o brinquedo em uma segunda localização, "B", sob condições idênticas ao lado A. Tipicamente por volta do 9 meses de idade, crianças, mesmo olhando esse jogo de esconder e procurar volta a alcançar o brinquedo A depois de o experimentador ter dado a dica no brinquedo B. Explicações iniciais do erro "A não B" são retratados como um problema de codificação do novo local, fragilidade da memória para o novo local, ou a ação repetida. Por outro lado, as crianças perseveram menos nas tentativas em B se os locais A e B são distintos visualmente. Entretanto observamos que a informação visual na tarefa "A não B" é importante para o aparecimento ou não da perseveração motora. A proposta deste estudo foi verificar se crianças com deficiência visual perseveram ou não na tarefa modificada Pigetiana de alcance "A não B", identificar o relacionamento das diferentes propriedades do objeto na taxa de perseverativa, identificar o relacionamento entre a orientação da cabeça e o alcançar durante sua performance, bem como o padrão cinemático do alcançar. Dez bebês com deficiência visual, baixa visão, entre 1 a 4 anos de idade foram autorizados por seus pais para participarem do estudo. As crianças foram avaliadas em duas condições: luminosa e sonora. Enquanto realizaram a tarefa "A não B", todos os participantes foram filmados por três câmeras. Os resultados revelaram que o grupo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Motor perseveration has recently been used to interpret the canonical Piaget's "A not B" task. In this task, the infants watch as the researcher hides a toy in a location "A", a delay is imposed, and then the infants are allowed to reach. On these A trials, infants typically reach to A, to where the object was hidden. After several hidings and successive reaches to A, the researcher hides the toy in a second location, "B", under identical conditions of the location A. Typically, around the age of nine months, infants, even after watching these "hide and search" games, return to reach for the "A" toy after being cued to reach for the "B" toy. Initial explanations for the "A not B" error portrayed it as a problem of encoding the new location, fragility of memory for the new location, or repeated action. On the other hand, infants are less likely to perseverate on attempts to B if the A and B locations are visually distinct. However, we observed that visual information in the "A not B" task is important to the emergence or not of the motor perseveration. The purpose of this study was to determine whether or not children that that have visual deficiency perseverate in a modified Piagetian "A not B" reaching task, to identify the relationship between different characteristics of the object and motor perseveration rate, and also, to identify the relationship between head orientation and reaching during their performance, as well as, the reaching kinematics pattern. Ten visually impaired children, low vision, among age of 1 and 4 years, were authorized by their parents to take part in this study. The children were measured in two conditions: luminous and sonorous. While performing the "A not B" sand box task, all participants were videotaped with three cameras. A section experiment showed results confirming that the group only perseverated under... (Complete abstract click electronic access below) / Mestre

<p>Tool use is an important area of research in psychology, neurophysiology, and motor behavior because it provides insights into the organization of perception, cognition, and action. Tool use research has traditionally focused on the neural structures or cognitive processes that contribute to body-tool integration, while there has been comparatively little interest in motor control. When tool use actions are studied, adaptations have mainly been examined at the level of manual control, while postural control and multi-segment coordination have received less attention. Examining these components of behavior in the context of tool use is vital for developing a better understanding of how humans integrate tools into goal-directed actions.</p><p>The goals of this dissertation were to 1) characterize adaptations to postural control over time when performing a manual task with a tool under different levels of postural constraint and determine their relation to manual task performance, 2) examine postural-manual coupling under different levels of postural constraint during tool use, and 3) determine how multi-segment coordination supports postural stability and suprapostural task performance under different levels of postural constraint during tool use. To address these questions, we adopted a sensorimotor adaptation paradigm to examine postural-manual control and multi-segment coordination before, during, and after an extended bout of tool use.</p>Tool-use adaptations were found to extend beyond the end-effector. Postural control played a crucial role in facilitating improvements in the manual control of tools. Placing constraints on posture interfered with these adaptations, disrupting the coordination of postural-manual behaviors during tool use. However, multi-segment coordination was modified to overcome this challenge and facilitate postural stability and manual performance. These results demonstrate that healthy young adults are capable of flexibly recruiting and exploiting available degrees of freedom in a task-dependent manner the potential challenges associated with integrating tools into movements. This dissertation provides preliminary support for the importance of considering postural control in tool use actions and highlights the utility of examining interactions across multiple levels of motor behavior—postural control, manual control, postural-manual coupling, and multi-segment coordination—to elucidate how tools are integrated into complex, goal-directed behaviors.

There is a paucity of data on neurochemical abnormalities and associated effects on cognition and motor performance in rats ontogenetically treated with quinpirole, a rodent model of dopaminergic hyperfunction. The objective of the current study was to analyze the cognitive and motor effects produced by ontogenetic administration of quinpirole, a dopamine D2/D3 receptor agonist. Past research from this laboratory has shown that ontogenetic quinpirole treatment sensitizes D2 receptors and produces a variety of characteristic stereotypic behaviors in adult rats. In the current study, rats received quinpirole HCl (1 mg/kg/day) or saline from postnatal day (PD) 1 to PD 11 and went otherwise untreated until adulthood (PD 60). In Experiment 1, cognitive performance was assessed on the standard and matching-to-place versions of the Morris water task (MWT). In Experiment 2, skilled motor performance was assessed on the Whishaw reaching task and locomotor activity was also analyzed. We found that ontogenetically quinpirole-treated rats displayed a deficit on the probe trial given at the end of training of the standard version of the MWT but that there were no significant differences from control on the matching-to-place task. Additionally, rats treated in ontogeny with quinpirole showed significant enhancement in reaching accuracy on the Whishaw reaching task as well as increased locomotor activity relative to saline controls. These findings demonstrate that ontogenetic quinpirole treatments produce cognitive deficits, enhanced skilled reaching and hyperlocomotion. The behavioral changes produced by ontogenetic quinpirole treatment are consistent with dopaminergic hyperfunction, and possible mechanisms are discussed.

Neonatal quinpirole (dopamine D(2)/D(3) agonist) treatment to rats has been shown to increase dopamine D(2) receptor sensitivity throughout the animal's lifetime. Male and female Sprague-Dawley rats were neonatalally treated with quinpirole (1 mg/kg) from postnatal days (P) 1-21 and raised to adulthood. Beginning on P62, rats were administered the atypical antipsychotic olanzapine (2.5 mg/kg) twice daily for 28 days. Starting 1 day after the end of olanzapine treatment, animals were behaviorally tested on the place and match-to-place version of the Morris water maze (MWM) over seven consecutive days, and a yawning behavioral test was also performed to test for sensitivity of the D(2) receptor 1 day following MWM testing. Similar to results from a past study, olanzapine alleviated cognitive impairment on the MWM place version and increases in yawning produced by neonatal quinpirole treatment. Brain tissue analyses showed that neonatal quinpirole treatment resulted in a significant decrease of hipppocampal ChAT and BDNF RNA expression that were unaffected by adulthood olanzapine treatment, although adulthood olanzapine treatment produced a significant increase in cerebellar ChAT RNA expression. There were no significant effects of drug treatment on NGF RNA expression in any brain area. These results show that neonatal quinpirole treatment produced significant decreases of protein RNA expression that is specific to the hippocampus. Although olanzapine alleviated cognitive deficits produced by neonatal quinpirole treatment, it did not affect expression of proteins known to be important in cognitive performance.

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第12817号 / 論医博第2079号 / 新制||医||1004(附属図書館) / 31304 / 京都大学大学院医学研究科脳統御医科学系専攻 / (主査)教授 河野 憲二, 教授 金子 武嗣, 教授 大森 治紀 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

<p>In many occupational tasks, environmental constraints limit how close a worker can place their body to a desired element of the task. Although this provides an obstacle when performing the task, workplace obstructions can often be used by a worker to externally support their body by means of bracing. The purpose of this thesis was to identify how a worker’s posture would differ when the task must be performed with a constrained reach, compared to having the option to externally support against the thighs. At 4 different task hand Locations, subjects performed 6 exertions, comprised of 2 Loads (27.5 N and 55 N) and 3 Directions (Up, Down, and Pull). Subjects were able to choose if bracing would be used when performing the first 24 trial exertions. After the choice conditions had been collected, trials were performed again with a forced brace or unbraced. The most important finding of this study was that participants were twice as likely to brace when performing a task with a far reach. In addition, average brace forces were approximately 117 N for Up and Pull exertions, and were nearly half that (67 N) for Down exertions. Participants would brace at a lower height at low versus high locations. Flexing the trunk forward and twisting the right shoulder forward, combined with a more flexed task arm and reduced shoulder rotation, allowed participants to adopt a posture where their shoulder was closer to the point of exertion during braced exertions, thereby increasing their functional arm length.</p> / Master of Science in Kinesiology

Greater than 50% of all spinal cord injuries (SCIs) in humans occur at the cervical level and the biggest desire of quadriplegic patients is recovery of hand and digit function. Several weeks after spinal cord injury, re-organization and re-modeling of spared endogenous pathways occurs and plasticity of both supraspinal and interneuronal networks are believed to mediate functional recovery. Propriospinal interneurons (PNs) are neurons found entirely in the spinal cord with axons projecting to different spinal segments. PNs function by modulating locomotion, integrating supraspinal motor pathways and peripheral sensory afferents. Recent studies have postulated that if PNs are spared following SCI, these neurons can contribute to functional recovery by establishing synaptic connections onto motor neurons. However, to what extent cervical PNs are involved in recovery of reaching behavior is not known. In our first study, we generated a lentiviral vector that permits highly efficient retrograde transport (HiRet) upon uptake at synaptic terminals in order to map supraspinal and interneuronal populations terminating near forelimb motoneurons (MNs) innervating the limb. With this vector, we found neurons labeled within the C3-C4 spinal cord and in the red nucleus, two major populations which are known to modulate forelimb reaching behavior. We also proceeded to use a novel two-viral vector method to specifically label ipsilateral C3-C4 PNs with tetracycline-inducible GFP. Histological analysis showed detailed labeling of somas, dendrites along with axon terminals. Based on this data, we proceeded to determine the contribution of C3-C4 PNs and rubrospinal neurons on forelimb reaching and grasping before and after cervical SCI. In our second study, we have examined a double-infection technique for shutdown of PNs and rubrospinal neurons (RSNs) in adult rats. Adult rats were microinjected with a lentiviral vector expressing tetracycline-inducible inhibitory DREADDs into C6-T1 spinal levels. Adeno-associated viral vectors (AAV2) expressing TetON mixed with GIRK2 were injected into the red nucleus and C3-C4 spinal levels respectively. Rats were tested for deficits in reaching behaviors upon application of doxycycline and clozapine-n-oxide (CNO) administration. No behavioral deficits were observed pre-injury. Rats then received a C5 spinal cord lesion to sever cortical input to forelimb motoneurons and were allowed four weeks to spontaneously recover. Upon re-administration of CNO to activate inhibitory DREADDs, deficits were observed in forelimb reaching. Histological analysis of the C3-C4 spinal cord and red nucleus showed DREADD+ neurons co-expressing GIRK2 in somas and dendrites of PNs and RSNs. PN terminals expressing DREADD were observed near C6-T1 motoneurons and in the brainstem. Control animals did not show substantial deficits with CNO administration. These results indicate both rubro- and propriospinal pathways are necessary for recovery of forelimb reaching. In a separate study, we sought to determine if promoting severed CST sprouting rostral to a C5 lesion near C3-C4 PNs could improve behavioral recovery post SCI. Past studies have examined sprouting and regeneration of corticospinal tract (CST) fibers post-cervical SCI through viral upregulation of key components of the PI3K/Akt/mTOR cascade. We examined the regenerative growth potential of CST fibers that are transduced with AAV2 expressing constituively active Akt3 or STAT3 both separately and in combination (Akt3 + STAT3). We have observed significant increases in CST axonal sprouting and regeneration in Akt3 and Akt3 + STAT3 transduced samples. However, no recovery was observed as animals transduced with viral constitutively active Akt3 displayed an epileptic phenotype. Further, epileptic animals with constitutively active Akt3 were found to have significant cortical neuron cell hypertrophy, activatived astrogliosis, increased dendritic arbors and hemimegencephalitis (HME). These results indicate a new model for examining mechanisms of HME and mTOR hyperactivity-induced epilepsy in adult rodents. / Biomedical Sciences