<p>Evidence suggests that children's pre-linguistic conceptual knowledge significantly influences the course of language acquisition. In a series of nine experiments we investigate this influence. We begin with two experiments using adult human subjects, in which we develop an analogue of children's early sensorimotor semantic representations and demonstrate that we have captured important aspects of meaning. We then use these sensorimotor semantic representations in simulation experiments using neural network models of language acquisition. First, we provide evidence that having these sensorimotor representations improves grammatical learning. Then we demonstrate that with these rich semantic representations there are strong correlations between the time course of lexical and grammatical learning analogous to those found in children. We suggest that this supports the position that grammar emerges from the formation of a rich lexicon. Finally, we show that it is not necessary to provide these sensorimotor representations for all words. We provide evidence that, given a directly grounded foundation of children's earliest words, the model can indirectly acquire grounded, embodied semantic representations for novel ungrounded words. Our results thus provide evidence that the initial structure of children's conceptual or semantic 'space' provides an important constraining and simplifying foundation that influences the course of later language acquisition.</p> / Doctor of Philosophy (PhD)

No description available.

Vocal learning is one of the most distinctive characteristics of the modern human species. Through the intricate interaction between vocal motor and auditory systems during early sensitive periods, humans spontaneously master the ability to speak and decode speech. Because vocal learning is so rare in vertebrates, songbirds (Oscines) are the primary model organisms used in studies of acoustic communication and vocal learning. The acquisition of songs in birds and speech in humans (learning of complex sounds with syntactic structures) exhibit similar developmental trajectories. Research on song learning has focused primarily on vocal production with limited emphasis on the role of auditory perception. While auditory tuning and sensorimotor feedback are indispensable for successful vocal learning and communication, how auditory tuning emerges at different levels of the neural processing hierarchy and how sensorimotor integration occurs in the brain during vocal learning is not fully understood. The neurobiology research described here thus focuses on auditory tuning and sensorimotor integration in vocal learning songbirds using multiple experimental approaches. In the first chapter, I describe peripheral auditory tuning in several songbird species. Using operant conditioning, I trained individual birds to report audible tones and assessed hearing thresholds over the 0.5 to 10 kHz frequency range. I also examined the relationship between song spectral energy and hearing by analyzing song frequency-power spectra and audiograms across species. I found that across songbird species, regardless of age, rearing condition, and sex, hearing range was similar: 0.5 to 8 kHz. Notably, the vocal energy in courtship song matches each species auditory sensitivity, indicating the coevolution of sensory and vocal motor systems. In the second chapter, I describe neuronal tuning in the auditory cortex (AC) of female songbirds. While male songbirds exhibit experience-dependent neuronal tuning in AC, the nature of AC tuning in females that do not sing has not been studied. I used in vivo acute electrophysiological recordings to examine neural responses to tones, ripple stimuli and songs. I compared neuronal firing patterns in female AC between different species groups and rearing conditions. My results suggest that higher-order auditory processing in female songbirds is conserved across species and that early song experience affects some aspects of tuning in the AC of females, suggesting that females exhibit experience-dependent changes in auditory tuning across development. In the final chapter, I examine a potential sensorimotor integration site, the caudal striatum (CSt), and its role in vocal learning. Auditory neurons in CSt suggest that the region may integrate auditory inputs and vocal motor commands to modulate sensorimotor learning. To study the effects of CSt lesions on song learning, I produced excitotoxic lesions in CSt across developmental stages. To label brain regions that project to or receive input from CSt, I injected anterograde or retrograde tracers into CSt. I also characterized the auditory tuning properties of CSt through electrophysiological recording. I found that CSt receives both dopaminergic and auditory projections but is not necessary for successful song learning. Electrophysiological data also show that auditory tuning properties of neurons in CSt are highly similar to neurons in other AC subregions, suggesting that CSt may be a sub-region of AC.

L'être humain utilise trois systèmes sensoriels distincts pour réguler le maintien de la station debout: la somesthésie, le système vestibulaire, et le système visuel. Le rôle de la vision dans la régulation posturale demeure peu connu, notamment sa variabilité en fonction de l'âge, du type développemental, et des atteintes neurologiques. Dans notre travail, la régulation posturale induite visuellement a été évaluée chez des participants au développement et vieillissement normaux âgés de 5-85 ans, chez des individus autistes (développement atypique) âgés de 12-33 ans, ainsi que chez des enfants entre 9-18 ans ayant subi un TCC léger. À cet effet, la réactivité posturale des participants en réponse à un tunnel virtuel entièrement immersif, se mouvant à trois niveaux de vélocité, a été mesurée; des conditions contrôles, où le tunnel était statique ou absent, ont été incluses. Les résultats montrent que la réactivité (i.e. instabilité) posturale induite visuellement est plus élevée chez les jeunes enfants; ensuite, elle s'atténue pour rejoindre des valeurs adultes vers 16-19 ans et augmente de façon linéaire en fonction de l'âge après 45 ans jusqu'à redevenir élevée vers 60 ans. De plus, à la plus haute vélocité du tunnel, les plus jeunes participants autistes ont manifesté significativement moins de réactivité posturale comparativement à leurs contrôles; cette différence n'était pas présente chez des participants plus âgés (16-33 ans). Enfin, les enfants ayant subi un TCC léger, et qui étaient initialement modérément symptomatiques, ont montré un niveau plus élevé d'instabilité posturale induite visuellement que les contrôles, et ce jusqu'à 12 semaines post-trauma malgré le fait que la majorité d'entre eux (89%) n'étaient plus symptomatiques à ce stade. En somme, cela suggère la présence d'une importante période de transition dans la maturation des systèmes sous-tendant l'intégration sensorimotrice impliquée dans le contrôle postural vers l'âge de 16 ans, et d'autres changements sensorimoteurs vers l'âge de 60 ans; cette sur-dépendance visuelle pour la régulation posturale chez les enfants et les aînés pourrait guider l'aménagement d'espaces et l'élaboration d'activités ajustés à l'âge des individus. De plus, le fait que l'hypo-réactivité posturale aux informations visuelles chez les autistes dépende des caractéristiques de l'environnement visuel et de l'âge chronologique, affine notre compréhension des anomalies sensorielles propres à l'autisme. Par ailleurs, le fait que les enfants ayant subi un TCC léger montrent des anomalies posturales jusqu'à 3 mois post-trauma, malgré une diminution significative des symptômes rapportés, pourrait être relié à une altération du traitement de l'information visuelle dynamique et pourrait avoir des implications quant à la gestion clinique des patients aux prises avec un TCC léger, puisque la résolution des symptômes est actuellement le principal critère utilisé pour la prise de décision quant au retour aux activités. Enfin, les résultats obtenus chez une population à développement atypique (autisme) et une population avec atteinte neurologique dite transitoire (TCC léger), contribuent non seulement à une meilleure compréhension des mécanismes d'intégration sensorimotrice sous-tendant le contrôle postural mais pourraient aussi servir comme marqueurs sensibles et spécifiques de dysfonction chez ces populations. Mots-clés : posture, équilibre, vision, développement/vieillissement sensorimoteur, autisme, TCC léger symptomatique, réalité virtuelle. / Maintaining upright stance is essential for the accomplishment of several goal-directed behaviors, such as walking. Humans use three distinct sensory systems to regulate their posture: the somatosensory, the vestibular and the visual systems. The role of vision in postural regulation remains poorly understood, notably its variability across the life-span, developmental type and neurological insult. Hence, visually-driven postural regulation was examined in typically developing and aging participants (5-85 years-old), as well as in atypically developing individuals with autism (12-33 years-old) and in children having sustained mTBI (9-18 years-old). In order to do so, participants' postural reactivity was assessed in response to a fully immersive virtual tunnel moving at 3 different velocities; control conditions were also included wherein the tunnel was either static or absent. Results show that visually-induced postural reactivity was strongest in young children, then attenuated to become adult-like between 16-19 years of age, and started increasing again linearly with age after 45 years until becoming strong again around 60 years. Moreover, at the highest tunnel velocity, younger autistic participants showed significantly less postural reactivity compared to age-matched controls and young adults (16-33 years-old). Finally, children having sustained mTBI, who were initially moderately symptomatic, exhibited increased visually-induced instability compared to their matched controls up to 12 weeks post-injury, although most of them (89%) were no longer highly symptomatic. Altogether, this suggests the presence of an important transition period for the maturation of the systems underlying sensorimotor integration in postural control at around 16 years of age, and further sensorimotor changes after 60 years of age; this over-reliance on vision for postural regulation in childhood and late adulthood could guide the design of age-appropriate facilities/ activities. Furthermore, the fact that postural hypo-reactivity to visual information present in autism is contingent on both the visual environment and on chronological age, enhances our understanding of autism-specific sensory anomalies. Additionally, the fact that children with mTBI show balance anomalies up to 3 months post-injury, even when they are no longer highly symptomatic may be related to altered processing of dynamic visual information and could have implications for the clinical management of mTBI patients, since symptoms resolution is commonly used as a criterion for return to activities. Finally, results stemming from populations with atypical development (autism) and with so-called transient neurological insult (mild TBI) not only contribute to enhance our understanding of sensorimotor integration mechanisms underlying postural control, but could also consist of sensitive and specific markers of dysfunction in these populations. Keywords : posture, balance, vision, sensorimotor development/ aging, autism, symptomatic mTBI, virtual reality.

L'être humain utilise trois systèmes sensoriels distincts pour réguler le maintien de la station debout: la somesthésie, le système vestibulaire, et le système visuel. Le rôle de la vision dans la régulation posturale demeure peu connu, notamment sa variabilité en fonction de l'âge, du type développemental, et des atteintes neurologiques. Dans notre travail, la régulation posturale induite visuellement a été évaluée chez des participants au développement et vieillissement normaux âgés de 5-85 ans, chez des individus autistes (développement atypique) âgés de 12-33 ans, ainsi que chez des enfants entre 9-18 ans ayant subi un TCC léger. À cet effet, la réactivité posturale des participants en réponse à un tunnel virtuel entièrement immersif, se mouvant à trois niveaux de vélocité, a été mesurée; des conditions contrôles, où le tunnel était statique ou absent, ont été incluses. Les résultats montrent que la réactivité (i.e. instabilité) posturale induite visuellement est plus élevée chez les jeunes enfants; ensuite, elle s'atténue pour rejoindre des valeurs adultes vers 16-19 ans et augmente de façon linéaire en fonction de l'âge après 45 ans jusqu'à redevenir élevée vers 60 ans. De plus, à la plus haute vélocité du tunnel, les plus jeunes participants autistes ont manifesté significativement moins de réactivité posturale comparativement à leurs contrôles; cette différence n'était pas présente chez des participants plus âgés (16-33 ans). Enfin, les enfants ayant subi un TCC léger, et qui étaient initialement modérément symptomatiques, ont montré un niveau plus élevé d'instabilité posturale induite visuellement que les contrôles, et ce jusqu'à 12 semaines post-trauma malgré le fait que la majorité d'entre eux (89%) n'étaient plus symptomatiques à ce stade. En somme, cela suggère la présence d'une importante période de transition dans la maturation des systèmes sous-tendant l'intégration sensorimotrice impliquée dans le contrôle postural vers l'âge de 16 ans, et d'autres changements sensorimoteurs vers l'âge de 60 ans; cette sur-dépendance visuelle pour la régulation posturale chez les enfants et les aînés pourrait guider l'aménagement d'espaces et l'élaboration d'activités ajustés à l'âge des individus. De plus, le fait que l'hypo-réactivité posturale aux informations visuelles chez les autistes dépende des caractéristiques de l'environnement visuel et de l'âge chronologique, affine notre compréhension des anomalies sensorielles propres à l'autisme. Par ailleurs, le fait que les enfants ayant subi un TCC léger montrent des anomalies posturales jusqu'à 3 mois post-trauma, malgré une diminution significative des symptômes rapportés, pourrait être relié à une altération du traitement de l'information visuelle dynamique et pourrait avoir des implications quant à la gestion clinique des patients aux prises avec un TCC léger, puisque la résolution des symptômes est actuellement le principal critère utilisé pour la prise de décision quant au retour aux activités. Enfin, les résultats obtenus chez une population à développement atypique (autisme) et une population avec atteinte neurologique dite transitoire (TCC léger), contribuent non seulement à une meilleure compréhension des mécanismes d'intégration sensorimotrice sous-tendant le contrôle postural mais pourraient aussi servir comme marqueurs sensibles et spécifiques de dysfonction chez ces populations. Mots-clés : posture, équilibre, vision, développement/vieillissement sensorimoteur, autisme, TCC léger symptomatique, réalité virtuelle. / Maintaining upright stance is essential for the accomplishment of several goal-directed behaviors, such as walking. Humans use three distinct sensory systems to regulate their posture: the somatosensory, the vestibular and the visual systems. The role of vision in postural regulation remains poorly understood, notably its variability across the life-span, developmental type and neurological insult. Hence, visually-driven postural regulation was examined in typically developing and aging participants (5-85 years-old), as well as in atypically developing individuals with autism (12-33 years-old) and in children having sustained mTBI (9-18 years-old). In order to do so, participants' postural reactivity was assessed in response to a fully immersive virtual tunnel moving at 3 different velocities; control conditions were also included wherein the tunnel was either static or absent. Results show that visually-induced postural reactivity was strongest in young children, then attenuated to become adult-like between 16-19 years of age, and started increasing again linearly with age after 45 years until becoming strong again around 60 years. Moreover, at the highest tunnel velocity, younger autistic participants showed significantly less postural reactivity compared to age-matched controls and young adults (16-33 years-old). Finally, children having sustained mTBI, who were initially moderately symptomatic, exhibited increased visually-induced instability compared to their matched controls up to 12 weeks post-injury, although most of them (89%) were no longer highly symptomatic. Altogether, this suggests the presence of an important transition period for the maturation of the systems underlying sensorimotor integration in postural control at around 16 years of age, and further sensorimotor changes after 60 years of age; this over-reliance on vision for postural regulation in childhood and late adulthood could guide the design of age-appropriate facilities/ activities. Furthermore, the fact that postural hypo-reactivity to visual information present in autism is contingent on both the visual environment and on chronological age, enhances our understanding of autism-specific sensory anomalies. Additionally, the fact that children with mTBI show balance anomalies up to 3 months post-injury, even when they are no longer highly symptomatic may be related to altered processing of dynamic visual information and could have implications for the clinical management of mTBI patients, since symptoms resolution is commonly used as a criterion for return to activities. Finally, results stemming from populations with atypical development (autism) and with so-called transient neurological insult (mild TBI) not only contribute to enhance our understanding of sensorimotor integration mechanisms underlying postural control, but could also consist of sensitive and specific markers of dysfunction in these populations. Keywords : posture, balance, vision, sensorimotor development/ aging, autism, symptomatic mTBI, virtual reality.

Title: The effect of one-off so called sensorimotor serie exercise on postural stability measured on Neurocom SMART Equitest Aim: The goal of this thesis is to evaluate the effect of one-off so-called sensorimotor serie exercise on postural stability on a healthy young human measured by computerized dynamic posturography (CDP). Methods: This experimental study is using a cross-over design, it means that participants got the intervention in randomized order. 20 healthy young subjects participated in the experiment, 12 women and 8 men aged 20 to 28 years (23,55± 1,63). The group of men and women was randomly divided into two groups. Group E1 was measured by Neurocom SMART Equitest using three testing protocols (SOT, MCT, LOS), went through the one-off so called sensorimotor serie, and was measured again immediately afterwards (almost 30 minutes after the first measurement) at the first appointment. In 1 week ± 1 day (wash-out period) participants from the group E1 were only measured without getting any intervention and after 30 minutes break measured again. Group E2 got the intervention in opposite order. Measured data were processed using the Neurocom Balance Manager Software. In the statistical analysis was used one-sample t-test respectively two-sample t-test (Welch's version) as a comparison...

In this dissertation, I have focused on the role of serotonin (5-HT) as a modulator in heart rate, feeding and locomotion behaviors as well as sensorimotor circuit activity in Drosophila melanogaster. A general overview in the actions of the serotonergic (5-HTergic) system on the larval heart and nervous system in larvae and adults is reviewed in Chapter One. I sought to further study the actions of serotonergic system to provide additional insights into cellular and molecular underpinnings in the actions of 5-HT.In Chapter two, I present studies on mechanisms of action by 5-HT in larvae cardiac system. For this purpose, genetic and pharmacological approaches were used. The transgenic flies used expressed hM4Di receptors (designer receptors exclusively activated by designer drugs (DREADDs)) which were employed to manipulate the activity of Gαi heterotrimeric protein through activation of engineered G-protein coupled receptors hM4Di DREADD. The activation of hM4Di DREADD receptors by clozapine-N-oxide (CNO) arrested the heart beat; however, pharmacological manipulation of adenylyl cyclase activity and cAMP levels had no significant effect on heart rate. In Chapter Three the role of various 5-HT receptor subtypes that mediate 5-HT action in larval cardiac tissue is addressed. In this study, various 5-HT agonists and antagonists were employed. The pharmacological results demonstrate that a 5-HT2 agonist significantly increases the heart rate. Furthermore, 5-HT2 antagonist, markedly reduces the effect of 5-HT. In addition, I employed genetic approaches to corroborate the pharmacological results. In addition, I investigated the role of the 5-HTergic system in locomotion and feeding behaviors as well as in modulation of sensorimotor circuits. This study is delineated in Chapter Four. The 5-HT biosynthesis was dysregulated by feeding Drosophila larvae various pharmacological agents. 5-HT receptor subtypes were manipulated using RNA interference mediated knockdown and 5-HT receptor insertional mutations. Moreover, synaptic transmission at 5-HT neurons was blocked or induced in both larvae and adult flies. The results demonstrate that disruption of components within the 5-HT system significantly impairs locomotor activity and feeding behavior in larvae. In addition, acute activation of 5-HT neurons disrupts normal locomotor activity in adult flies. In Chapter Five, I addressed direct actions of fluoxetine on synaptic transmission at neuromuscular junctions (NMJs), neural properties, and cardiac function unrelated to fluoxetine’s action as a selective 5-HT reuptake inhibitor using Drosophila, crayfish and primary neurons in mouse model system. Fluoxetine application blocked action potentials in crayfish axons, enhanced occurrences of spontaneous synaptic vesicle fusion events at NMJs of both Drosophila and crayfish. In rodent primary neurons, fluoxetine application resulted in increase of cytoplasmic Ca2+. I also developed teaching modules, which are presented in Chapter Seven, to guide students how to exploit a vast array of genetic tools, such as optogenetics in Drosophila to manipulate various neural circuits and to observe their effects on behavior and sensorimotor circuit activity. I also developed a module to teach college level students a hands-on experiment regarding proprioception and tension receptors in crab limb, which is detailed in Chapter Eight.

Thesis (MOccTher)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: As a South African occupational therapist (OT) trained to provide occupational therapy using a sensory integration approach (OT/SI), to children and their families, I have personal experience of different parent perceptions and experiences regarding OT/SI as a treatment approach to improving their children’s occupational performance. This made me question the various factors that may influence a parent’s perceptions and experiences, and how these factors may ultimately influence the outcome of OT/SI intervention for the child and family. Additionally, I wanted to know what OT/SI intervention was like for parents of a child with difficulties processing and integrating sensory information and what changes should be made to ensure we are meeting both child and parents’ needs. To date, no research exists regarding parents’ perceptions and experiences of OT/SI intervention in South Africa. Despite this, OT/SI intervention is widely used among South African paediatric occupational therapists. This study focused on the lived experience of OT/SI intervention for parents in the Western Cape, South Africa. The purpose of this study was to explore and describe South African parents’ perceptions and experiences of OT/SI intervention received. This study not only sought to explore whether parents thought OT/SI intervention was valuable or not, but also to understand the meaning, the broader context and the process by which parent’s opinions had come into being, and how these may have influenced the meaning ascribed to the intervention. The study sample consisted of nine parents, including mothers and a father, of children with difficulties processing and integrating sensory information, who lived in various regions of the Western Cape, South Africa. Purposive sampling was used to select participants in this study. Using a qualitative, phenomenological approach, data was collected during face=to=face interviews, participant observation and researcher’s field notes. Four themes that pertain to the aims of the study were revealed during the analysis. They included: “It was tough because we didn’t understand”, “Just suddenly everything made so much sense”, “Mobilized my child into the world”, and “OT/SI intervention facilitators proposed by participants”. These themes describe the progression of the participant’s perceptions and experiences before OT/SI intervention, during intervention, and after having received the intervention, as well as the recommendations they proposed to facilitate OT/SI intervention in South Africa. I found that factors such as poor awareness and understanding of OT/SI intervention amongst the participants negatively influenced their understanding of their child’s occupational performance, their role as parents and their social performance as a family in various social contexts. Key points of transformation were identified during the ‘input phase’ of OT/SI intervention, which either facilitated or created a barrier in the participants’ shift to the ‘after phase’ of OT/SI intervention. Despite the barriers, all participants perceived and experienced a shift to the ‘after phase’ of OT/SI intervention. For some participants, this shift included changes they perceived in their child, which influenced social performance of the child and family. However, for the majority of participants, this shift meant a number of factors: a better understanding and expectations of their child; changes in their child’s abilities, activities and self=worth; changes in themselves as parents and how this influenced their parent=child relationship; as well as changes in their child’s and family’s social performance in various contexts. Insight gained from the participants’ recommendations and my interpretation of findings, allowed recommendations to be made in an attempt to overcome the barriers and promote the facilitators that will make a difference to OT/SI intervention in South Africa. Recommendations were made within two contexts: the broader social context of South Africa and the context of OT/SI intervention received by children and their parents. / AFRIKAANSE OPSOMMING: As ‘n Suid=Afrikaanse arbeidsterapeut (AT), opgelei om arbeidsterapie met ‘n sensoriese integrasie benadering (AT=SI) te verskaf aan kinders en hul families, het ek persoonlike ondervinding van verskeie ouers se persepsies en ervarings omtrent AT=SI as ‘n behandelingsbenadering om die kind se arbeidsprestasie te bevorder. Dit het my laat wonder watter faktore die ouer se persepsies en ervarings sou beïnvloed, asook hoe hierdie faktore die uitkoms van die AT=SI behandeling vir die kind en die familie sou beïnvloed. Ek wou ook uitvind hoe die ouer van ‘n kind met SIA (SID), AT=SI intervensie beleef het en watter veranderinge behoort aangebring te word om te verseker dat beide die kind en die ouers se behoeftes nagekom word. Tot dusver bestaan daar geen navorsing aangaande die ouer se persepsies en ervarings van AT=SI intervensie in Suid=Afrika nie. Ten spyte hiervan word AT=SI alom gebruik deur pediatriese arbeidsterapeute in Suid=Afrika. Hierdie studie fokus dus op ouers se persoonlike ervaring van AT= SI intervensie in die Wes=Kaap, Suid=Afrika. Die doel van hierdie studie was om die persepsies en ervarings van Suid=Afrikaanse ouers wat AT= SI intervensie ontvang het, te ondersoek. Hierdie studie het nie net gepoog om vas te stel of die ouers gedink het dat AT=SI waardevol was aldan nie, maar ook om die betekenis, die breër konteks, en die proses waardeur hul opinies gevorm is en hoe dit hulle beïnvloed het, te verstaan. Die steekproef het bestaan uit nege ouers, insluitend moeders en ‘n vader, van kinders met SIA (SID), woonagtig in verskillende streke in die Wes=Kaap, Suid=Afrika. ‘n Doelgerigte steekproef is gebruik om die deelnemers vir die studie te kies. ‘n Kwalitatiewe=fenomenologiese benadering is gebruik om data in te samel deur aangesig=tot=aangesig onderhoude, waarneming van deelnemers, asook die navorser se veldnotas. Vier temas wat direk verwant was aan die doelwitte van die studie, is tydens die analise van die data geïdentifiseer. Dit het die volgende ingesluit: “Dit was moeilik want ons het nie verstaan nie”, “Ewe skielik het alles so baie sin gemaak”, “My kind in die wêreld gemobiliseer ”, “AT=SI intervensie fasiliteerders voorgestel deur die deelnemers”. Hierdie temas beskryf die vordering van die deelnemers se persepsies en ervarings voor die aanvang van AT=SI intervensie, gedurende die intervensie en ook nadat intervensie voltooi is, asook die aanbevelings wat hulle gemaak het om AT=SI intervensie in Suid=Afrika te fasiliteer. Ek het bevind dat faktore soos deelnemers se swak bewustheid en begrip van AT=SI intervensie, hul begrip van hul kind se arbeidsprestasie, hul rol as ouers en hul sosiale optrede as ‘n familie in verskeie sosiale kontekste, negatief beïnvloed het. Kernpunte van verandering is geïdentifiseer gedurende die ‘inset=fase’ van die AT=SI intervensie, wat die deelnemers se vordering na die ‘na= fase’ van AT=SI intervensie òf gefasiliteer het, òf bemoeilik het. Ten spyte van die struikelblokke het alle deelnemers ‘n skuif na die ‘na=fase’ van AT=SI intervensie waargeneem en ervaar. Vir sommige deelnemers was hierdie skuif die veranderde optrede wat hulle in hul kind waargeneem het, wat die kind en familie se sosiale gedrag verander het. Vir die meerderheid deelnemers het hierdie skuif egter ‘n aantal faktore ingesluit: ‘n beter begrip en verwagting van hulle kind; veranderinge in hulle kind se vermoëns, aktiwiteite en eiewaarde; veranderinge in hulself as ouers en hoe dit hul ouer=kind verhouding beïnvloed het; asook veranderinge in die kind en familie se sosiale gedrag in verskeie kontekste. Die deelnemers se voorstelle en my interpretasie van die bevindinge het my in staat gestel om voorstelle te maak om die struikelblokke te probeer oorkom en die fasiliteerders aan te moedig wat die verskil gaan maak in AT=SI intervensie in Suid=Afrika. Aanbevelings is gemaak vir twee areas: die wyer sosiale konteks van Suid=Afrika, asook die konteks van die AT=SI intervensie wat ontvang word deur kinders en hulle ouers.

Sensory neocortex contains a significant number of inhibitory neurons that use gamma-aminobutyric acid (GABA) as their neurotransmitter. Functional roles for these neurons have been identified in physiological studies. For example, in primary somatosensory cortex (SI), blockade of GABAa receptors with bicuculline leads to expansion of receptive fields (RFs). The magnitude of RF enlargement varies between SIpopulations of GABAergic neurons were identified by labeling specific calcium binding proteins.

La respiration est une activité motrice autonome rythmique au cours de laquelle de nombreux muscles se contractent de manière coordonnée afin de produire des mouvements ventilatoires adaptés aux contraintes environnementales et aux exigences de l'organisme. Cette fonction vitale doit être fiable et adaptable à très court terme, c’est pourquoi elle est influencée, entre autres, par un grand nombre d’activités motrices. Par exemple, lors d’exercices physiques, le rythme respiratoire peut se coupler au rythme locomoteur. Les objectifs de ce travail doctoral sont centrés sur l’exploration des mécanismes neurogènes à la base du couplage entre ces deux fonctions motrices chez le rat nouveau-né. Pour une grande partie, cette étude a été réalisée sur préparation isolée in vitro de tronc cérébral-moelle épinière de rat nouveau-né (0 à 3 jours), ce modèle permettant de conserver dans leur intégrité les centres responsables des rythmes respiratoire et locomoteur. Compte tenu de l’accessibilité directe aux réseaux neuronaux, les mécanismes de couplage et d'entraînement respiratoire ont été abordés par des approches combinées électrophysiologique, neuroanatomique, pharmacologique et lésionnelle. Dans ce contexte, un des principaux résultats de ce travail doctoral est le rôle crucial joué par les informations sensorielles en provenance des membres antérieurs et postérieurs dans l'entraînement respiratoire observé lors de séquences locomotrices. Ainsi, les afférences proprioceptives spinales capables de réinitialiser et d'entraîner l’activité des centres respiratoires bulbaires via un relais pontique, établissent également des connexions sur l’ensemble des populations de motoneurones spinaux respiratoires phréniques, intercostaux et abdominaux. / Respiration is an autonomous rhythmic motor activity that requires the coordinated contractions of diverse muscles to produce ventilatory movements adapted to organismal needs. This crucial physiological function must be reliable and adaptable on a short-term basis, and requires coordianted movements with various other motor activities. For instance, respiratory rhythmicity becomes coupled to locomotion during physical exercise. My doctoral work aimed to explore the neurogenic mechanisms underlying the interactions between these two motor functions in the neonatal rat. This work was mainly conducted on isolated in vitro brain stem-spinal cord preparations of newborn rats (0-3 days), an experimental model that allows the maintenance of the still functional respiratory and locomotor CPGs in vitro. Due to the easy access to the neuronal networks in these preparations, locomotor-respiratory coupling and respiratory entrainment mechanisms were investigated by combined electrophysiological, neuroanatomical, pharmacological and lesional approaches. A major finding was the crucial played by sensory information from fore- and hindlimb in respiratory entrainment induced by locomotor rythmicity. Spinal sensory afferents can reset and entrain the activity of the medullary respiratory centres via a pontine relay, as well as making direct connections with the various spinal respiratory motoneuron (phrenic, intercostal and abdominal) populations.