Aim: The aim of this thesis is both evaluate a somatognosis quality and consider rate of personality dimensions in patients with FBSS. Methods: 30 patients with FBSS and 25 probands of healthy control group were examinated in laboratory of spatial cognition called Blue Velvet Arena. They underwent spatial navigation task and body scheme tests. We made comparative analysis of these measurements between groups. We evaluated personality dimensions in patients group, by using NEO personality inventory and Petrie test. Finally we consider relationships of these variables and another related factors. Results: Signicant difference between patient's group and control group was found both in spatial navigation task and body scheme tests. In spatial navigation task control group had lower results compared to the patient's group. In body scheme tests was found reverse results. We found high correlation of body scheme with age, pain duration and activity level. There was high percentage of underestimating probands and probands with high score of conscientiousness. Error rate (judgement out of tolerance zone) was higher in patient's group compared to the control group. Conclusions: Our results states that patients with FBSS have lower quality of somatognosis in light of body scheme. We hypothesise, that body...

As pessoas interagem diariamente com seu ambiente e, embora possa parecer simples, esta interação recruta diferentes fontes de informações visuais e não visuais que podem ser usadas no processamento da distância durante a locomoção. Baseado nisto, o objetivo deste estudo foi avaliar o desempenho de crianças e adolescentes em tarefas envolvendo distância e orientação espacial durante o caminhar de rotas retilíneas e triangulares, na ausência de informações visuais e auditivas. Para tanto, grupos de voluntários de ambos os sexos, G1 (7-8 anos), G2 (9-10 anos) e G3 (12-16 anos), realizaram três tarefas em ambientes naturais. A tarefa I consistiu em caminhar diretamente a um alvo, com a visão ocluída, após vê-lo brevemente. A tarefa II consistiu em caminhar distâncias em linha reta, com a visão ocluída, pelo guiar de um condutor, e subsequentemente, ao girar em sentido horário ou anti-horário, retornar sozinho à origem do percurso. A tarefa III foi similar a tarefa II, mas com rotas triangulares; o participante, com a visão ocluída, caminhou as duas primeiras arestas do triângulo guiadas por um condutor, e a aresta complementar, percorrida sozinho retornando à origem do percurso. Em cada tarefa foram mensuradas as distâncias caminhadas e os desvios de orientação, sendo que as distâncias consideradas como acuradas eram de 4, 8 e 16 m. Os resultados em todas as tarefas demonstraram que a acurácia na produção das distâncias depende da amplitude da distância percorrida independente da idade. Nas tarefas I e II, a distância de 4 m exerceu maior efeito sobre o G1, possivelmente devido à menor experiência sensório-motora destes participantes sobre relações físicas espaciais e como elas surgem para os seus sentidos. Em relação à manutenção da orientação, nas tarefas I e III, todos os grupos apresentaram maiores desvios na distância de 16 m. Ainda, na tarefa III o girar em sentido anti-horário no retorno à origem aumentou o grau dos desvios bem como as distâncias caminhadas. Em conclusão, nossos resultados sugerem que a acurácia do desempenho depende da amplitude das distâncias e da complexidade da tarefa. / People interact daily with their environment and, although it may seem simple, this interaction recruits different sources of information, both visual and non-visual, which can be used for distance processing during locomotion. Based on this, the objective of this study was to assess the performance of children and adolescents in tasks involving distance and spatial orientation during walking in a straight lines and triangular routes, in the absence of visual and auditory cues. Thus, groups of volunteers, G1 (7-8 yrs), G2 (9-10 yrs) and G3 (12-16 yrs), accomplished three tasks. Task I consisted of walking blindfolded directly towards a target, after seeing it briefly. Task II consisted of walking blindfolded in a straight lines distances, led by the experimenter, and subsequently, to turn clockwise or anti-clockwise, returning to the origin of the route alone. Task III was similar to task II, but the routes were triangular, the participant blindfolded walked the first two edges of the triangle guided by a driver, and the additional edge, traveled alone back to the origin of the route. Walking distance and direction deviation were measured in each task, given that the distances were accurate considered accurate were 4, 8 and 16 m. The results in all tasks showed that the accuracy in the production of distances depend on the magnitude of the distance travelled, irrespective of age. In tasks I and II, a distance of 4 m had stronger effect on the G1, possibly the lower sensory-motor experience of the participants about physical spatial relations and how they appear to your senses.Regarding the maintenance of orientation in tasks I and III, all groups showed larger deviations in the distance of 16 m. Besides, in task III rotating counter-clockwise increased not only the desviations, but also the walked distances. In conclusion, our results suggest that the accuracy of performance depends on the distances amplitudes and the complexity of the task.

No andar, o risco de quedas em idosos é maior. O objetivo é estudar o risco de quedas na locomoção sem visão e a relação entre orientação espacial, veering e controle postural. Participaram 27 adultos (25,2±4,5 anos, 1,68±0,10m, 63,8±10,3kg); 27 idosos AF (72,1±4,3 anos, 1,60±0,09m, 68,5±13kg); 12 idosos RQ (72,3±6 anos, 1,57±0,08m, 67,4±10,9kg). Eles caminharam 15m sem visão com um acelerômetro fixo entre L1 e L2. Variáveis: grupo; variabilidade do desvio; erro absoluto e variável; DFA; Tc; HST; DLT. O idoso RQ teve maior variabilidade do desvio (F(2,63)=4,6, p=0,01), erro absoluto (F(2,63)=16,64, p<0,0001) e variável (F(2,63)=4,5, p=0,01). Grupo (F(2,652)=48,9, p<0,0001) e direção (F(1,652)=444,5, p<0,0001) afetaram o DFA, e foi maior nos idosos e em AP (p<0,0001). O grupo (F(2,652)=29,3, p<0,0001) e direção (F(1,652)=605, p<0,0001) afetaram o HST, no idoso RQ e na ML (p<0,0001). O grupo (F(2,652)=30,8, p<0,0001) e direção (F(1,652)=178, p<0,0001) afetaram HLT,que foi maior nos idosos e em ML (p<0,0001). A forma como o indivíduo caminha nas direções ML e AP são diferentes. O controle da oscilação é anti-persistente na direção ML e persistente na AP. Os idosos dependem mais da visão na estabilização ML na locomoção. Os idosos RQ apresentam maior veering, os idosos AF e adultos têm veering semelhante. A AF pode retardar o envelhecimento quanto à estabilidade dinâmica e à memória espacial durante a locomoção sem visão, diminuindo o risco de quedas / For elderly, the risk to fall increases during walking. The aim of this project is to study the risk to fall in elderly during gait without vision and its relation to spatial orientation, veering and postural control. The subjects were 27 adults (25.2±4.5 years old, 1.68±0,10 m height, 63.8±10.3 kg weight); 27 elderly AF (72.1±4.3 years old, 1.60±0.09 m height, 68.5±13 kg weight); 12 elderly RQ (72.3±6 years old, 1.57±0.08m height, 67.4±10.9 kg weight). The subjects were instructed to walk straight ahead with their eyes closed for 15 m, with an accelerometer fixed between L1 and L2. The variables were: group; target variability; absolute and variable error; DFA; Tc; HST; DLT. The elderly RQ showed the highest target variability (F(2,63)=4.6, p=0.01), absolute (F(2,63)=16.6, p<0,0001) and variable error (F(2,63)=4.5, p=0.01). Group (F(2,652)=48.9, p<0.0001) and direction (F(1,652)=444, p<0.0001) affected DFA, AP and elderly showed the highest values (p<0.0001). Group (F(2,652)=29.3, p<0.0001) and direction (F(1,652)=605, p<0.0001) affected HST, elderly RQ and ML showed the highest values (p<0.0001). Group (F(2,652)=30.8, p<0.0001) and direction (F(1,652)=178, p<0.0001) affected HLT, all elderly and ML showed the highest values (p<0.0001). The direction affects gait control, it is anti-persistent for ML direction and persistent for AP direction. The lack of visual information affects more the elderly in ML direction. The elderly RQ showed larger veering; while the others were similar. Physical activity may slow down the aging process by affecting the dynamic stability and spatial memory during gait without vision, leading to reduce the risk of fall

No estudo da cognição espacial de primatas selvagens, a capacidade de representação da localização espacial de objetivos é habitualmente inferida por mudanças no padrão de deslocamento. A maioria das pesquisas nessa área observa se existem variações na linearidade e velocidade, em função do objetivo. Contudo, poucas pesquisas têm estudado se outros fatores poderiam afetar esses padrões, como variáveis climáticas. O objetivo deste trabalho foi verificar se variações em precipitação e temperatura modificam os padrões de deslocamento de um grupo de macacos-prego da Mata Atlântica. Os macacos foram acompanhados por um ano durante as duas estações consideradas para coletar dados comportamentais. Os dados climáticos foram fornecidos pelo INMET e as rotas foram coletadas com tecnologia GPS. Analisaram-se segmentos diários para objetivos espaciais e segmentos sem objetivo. Em cada segmento calculou-se velocidade e linearidade. Os resultados mostraram que existiu pouca influência da chuva nas variáveis controladas. Entretanto, algumas medidas de linearidade foram afetadas significativamente pela temperatura. Por incluir mudanças da distribuição do alimento, a sazonalidade foi mais explicativa de velocidade e linearidade que as variáveis climáticas. Nossos resultados sugerem que mudanças de velocidade e linearidade em deslocamentos para objetivo são indicadores confiáveis de representação de localização espacial / In studies of wild primates spatial cognition by means of natural observation, changes in navigation patterns, particularly travel speed and linearity depending on the spatial target, are usually considered as indicative of the ability of representing and locating spatial goals. However, few investigations have considered whether other factors, such as climatic conditions, could be affecting those navigation patterns. Our goal here was to verify if variations on rainfall and temperature can modify the navigation patterns of a black capuchin monkeys group in the Brazilian Atlantic Forest. For collecting behavioural data, the group was followed during a year in both seasons. The National Institute of Meteorology (INMET) provided the weather data and routes were collected with GPS technology. Goal and non-goal daily segments were analyzed. For each segment, travel speed and linearity index were calculated. Results showed that there was little influence of rainfall on the controlled variables. Nevertheless, some measurements of linearity were influenced by temperature. Seasonality was a better predictor of travel speed and linearity than weather conditions due to changes in food distribution. Our results suggest that changes in travel speed and linearity towards goals are good indicators of the representation of spatial locations

O processo de tomada de decisão tem sido estudado em várias espécies de formigas e em diversos contextos, especialmente durante o forrageamento e a escolha do local do ninho. Nesses estudos, os cientistas tentam entender quais são os mecanismos envolvidos na seleção de um determinado local para o ninho ou de rota de forrageamento. Há poucas pesquisas sobre tomada de decisão em relação ao descarte de lixo. O lixo pode ser uma fonte de patógenos. Seu manejo é importante para insetos eusociais, como as formigas cortadeiras, pois a proximidade genética entre os indivíduos do ninho facilita a disseminação de doenças. O projeto visa estudar o comportamento da Atta sexdens frente ao lixo, dando especial atenção ao processo de tomada de decisão, às estratégias para descarte de lixo, à orientação no transporte de lixo e à forma como as operárias lidam com ele. Para isso, realizamos uma série de procedimentos experimentais, cuja metodologia incluiu o uso de labirintos e pontes em diferentes formatos e a observação do comportamento das operárias. Em geral, observamos que as formigas, assim como visto na literatura, preferem isolar o lixo do resto da colônia. Com a Atta sexdens, isso costuma ocorrer em câmaras sob a terra, unidas ao formigueiro, mas longe de fungos. O ambiente laboratorial não permite que isso ocorra, o que faz com que elas busquem meios alternativos para isolar o lixo. Esse isolamento pode ocorrer usando potes dentro da bandeja de ninho, mas parece haver preferência em colocar o lixo fora dela, em outra bandeja, por exemplo, interligada àquela em que ficam os potes com fungos. Sempre que há esse espaço externo para o depósito de detritos, as formigas transportam o lixo para ele. Esse local não precisa ser o mais distante possível, ao contrário do que esperávamos. Para orientação, as lixeiras levam em consideração as diferentes pistas que possuem (químicas, visuais e outras, intrínsecas). Finalmente, temos evidências de que as formigas adaptam suas estratégias de forrageamento ao ambiente em que estão, evitando, por exemplo, a contaminação das folhas. Não encontramos evidências, no entanto, de agressividade contra as formigas contaminadas pelo lixo. Houve, porém, mais agressividade contra lixeiras que contra forrageadoras. Esses resultados vão parcialmente na direção esperada / The decision-making process has been studied in several species of ants and in different contexts, especially during the planning and selection of the nest site. In these studies, scientists try to understand which are the mechanisms involved in selecting a particular nest site or foraging route. There are a few studies on decision-making regarding waste disposal. Waste can be a source of pathogens. Its management is important for eusocial insects, such as leaf-cutting ants, since there is a genetic proximity between individuals, facilitating the spread of diseases. This project aims to study the behavior of Atta sexdens and how they manage their waste, focusing in the decision-making process, strategy for waste disposal, guidance on the transportation of waste and how workers deal with waste. For this, we performed a series of experimental procedures, whose methodology included the use of labyrinths and bridges in different formats and the observation of the behavior of the workers. In general, we observed that the ants, as seen in the literature, prefer to isolate the waste from the rest of the colony. In Atta sexdens, this usually occurs in chambers below ground, attached to the nest, but away from the fungus. The laboratory environment does not allow this to occur, which causes them to seek alternative means to isolate the waste. This isolation can occur using pots inside the nest tray, but it seems preferable to put the waste outside of it, for example in another tray, interconnected with that in which the pots with fungus are placed. Whenever there is this external space for debris deposit, the ants carry the waste for it. This place does not have to be as distant as possible, contrary to what we expected. For guidance, dumps take into account the different clues they have (chemical, visual, other intrinsic tracks). Finally, we have evidence that the ants adapt their foraging strategies to the environment they are in, for example to avoid contamination of the leaves. We found no evidence, however, of aggressiveness against ants contaminated with waste. There was, however, more aggressiveness against dumps than against foragers. These results are partly in the expected direction

No estudo da cognição espacial de primatas selvagens, a capacidade de representação da localização espacial de objetivos é habitualmente inferida por mudanças no padrão de deslocamento. A maioria das pesquisas nessa área observa se existem variações na linearidade e velocidade, em função do objetivo. Contudo, poucas pesquisas têm estudado se outros fatores poderiam afetar esses padrões, como variáveis climáticas. O objetivo deste trabalho foi verificar se variações em precipitação e temperatura modificam os padrões de deslocamento de um grupo de macacos-prego da Mata Atlântica. Os macacos foram acompanhados por um ano durante as duas estações consideradas para coletar dados comportamentais. Os dados climáticos foram fornecidos pelo INMET e as rotas foram coletadas com tecnologia GPS. Analisaram-se segmentos diários para objetivos espaciais e segmentos sem objetivo. Em cada segmento calculou-se velocidade e linearidade. Os resultados mostraram que existiu pouca influência da chuva nas variáveis controladas. Entretanto, algumas medidas de linearidade foram afetadas significativamente pela temperatura. Por incluir mudanças da distribuição do alimento, a sazonalidade foi mais explicativa de velocidade e linearidade que as variáveis climáticas. Nossos resultados sugerem que mudanças de velocidade e linearidade em deslocamentos para objetivo são indicadores confiáveis de representação de localização espacial / In studies of wild primates spatial cognition by means of natural observation, changes in navigation patterns, particularly travel speed and linearity depending on the spatial target, are usually considered as indicative of the ability of representing and locating spatial goals. However, few investigations have considered whether other factors, such as climatic conditions, could be affecting those navigation patterns. Our goal here was to verify if variations on rainfall and temperature can modify the navigation patterns of a black capuchin monkeys group in the Brazilian Atlantic Forest. For collecting behavioural data, the group was followed during a year in both seasons. The National Institute of Meteorology (INMET) provided the weather data and routes were collected with GPS technology. Goal and non-goal daily segments were analyzed. For each segment, travel speed and linearity index were calculated. Results showed that there was little influence of rainfall on the controlled variables. Nevertheless, some measurements of linearity were influenced by temperature. Seasonality was a better predictor of travel speed and linearity than weather conditions due to changes in food distribution. Our results suggest that changes in travel speed and linearity towards goals are good indicators of the representation of spatial locations

O processo de tomada de decisão tem sido estudado em várias espécies de formigas e em diversos contextos, especialmente durante o forrageamento e a escolha do local do ninho. Nesses estudos, os cientistas tentam entender quais são os mecanismos envolvidos na seleção de um determinado local para o ninho ou de rota de forrageamento. Há poucas pesquisas sobre tomada de decisão em relação ao descarte de lixo. O lixo pode ser uma fonte de patógenos. Seu manejo é importante para insetos eusociais, como as formigas cortadeiras, pois a proximidade genética entre os indivíduos do ninho facilita a disseminação de doenças. O projeto visa estudar o comportamento da Atta sexdens frente ao lixo, dando especial atenção ao processo de tomada de decisão, às estratégias para descarte de lixo, à orientação no transporte de lixo e à forma como as operárias lidam com ele. Para isso, realizamos uma série de procedimentos experimentais, cuja metodologia incluiu o uso de labirintos e pontes em diferentes formatos e a observação do comportamento das operárias. Em geral, observamos que as formigas, assim como visto na literatura, preferem isolar o lixo do resto da colônia. Com a Atta sexdens, isso costuma ocorrer em câmaras sob a terra, unidas ao formigueiro, mas longe de fungos. O ambiente laboratorial não permite que isso ocorra, o que faz com que elas busquem meios alternativos para isolar o lixo. Esse isolamento pode ocorrer usando potes dentro da bandeja de ninho, mas parece haver preferência em colocar o lixo fora dela, em outra bandeja, por exemplo, interligada àquela em que ficam os potes com fungos. Sempre que há esse espaço externo para o depósito de detritos, as formigas transportam o lixo para ele. Esse local não precisa ser o mais distante possível, ao contrário do que esperávamos. Para orientação, as lixeiras levam em consideração as diferentes pistas que possuem (químicas, visuais e outras, intrínsecas). Finalmente, temos evidências de que as formigas adaptam suas estratégias de forrageamento ao ambiente em que estão, evitando, por exemplo, a contaminação das folhas. Não encontramos evidências, no entanto, de agressividade contra as formigas contaminadas pelo lixo. Houve, porém, mais agressividade contra lixeiras que contra forrageadoras. Esses resultados vão parcialmente na direção esperada / The decision-making process has been studied in several species of ants and in different contexts, especially during the planning and selection of the nest site. In these studies, scientists try to understand which are the mechanisms involved in selecting a particular nest site or foraging route. There are a few studies on decision-making regarding waste disposal. Waste can be a source of pathogens. Its management is important for eusocial insects, such as leaf-cutting ants, since there is a genetic proximity between individuals, facilitating the spread of diseases. This project aims to study the behavior of Atta sexdens and how they manage their waste, focusing in the decision-making process, strategy for waste disposal, guidance on the transportation of waste and how workers deal with waste. For this, we performed a series of experimental procedures, whose methodology included the use of labyrinths and bridges in different formats and the observation of the behavior of the workers. In general, we observed that the ants, as seen in the literature, prefer to isolate the waste from the rest of the colony. In Atta sexdens, this usually occurs in chambers below ground, attached to the nest, but away from the fungus. The laboratory environment does not allow this to occur, which causes them to seek alternative means to isolate the waste. This isolation can occur using pots inside the nest tray, but it seems preferable to put the waste outside of it, for example in another tray, interconnected with that in which the pots with fungus are placed. Whenever there is this external space for debris deposit, the ants carry the waste for it. This place does not have to be as distant as possible, contrary to what we expected. For guidance, dumps take into account the different clues they have (chemical, visual, other intrinsic tracks). Finally, we have evidence that the ants adapt their foraging strategies to the environment they are in, for example to avoid contamination of the leaves. We found no evidence, however, of aggressiveness against ants contaminated with waste. There was, however, more aggressiveness against dumps than against foragers. These results are partly in the expected direction

Die sich im Verlaufe einer Demenz manifestierenden Orientierungsstörungen schränken die Selbständigkeit der Erkrankten ein und sind oftmals einer der Gründe für die Übersiedlung in eine Pflegeeinrichtung. Aufgrund ihrer krankheitsspezifischen kognitiven Einschränkungen ist es den Betroffenen dort erschwert, sich ihr neues Wohnumfeld zu erschließen. Demzufolge sind Demenzerkrankte zur Aufrechterhaltung von Mobilität und Selbständigkeit in einem ganz besonders hohen Maße von baulichen Strukturen abhängig, die ihnen räumliche, zeitliche und situative Orientierung bieten. Bisher liegen jedoch nur sehr wenige empirisch fundierte Forschungsarbeiten zu deren geeigneter Gestaltung vor. In dieser Dissertation wurde untersucht, welche baulichen Merkmale von Altenpflegeeinrichtungen das räumliche Orientierungsvermögen demenzerkrankter Bewohner beeinflussen. Dazu wurden die baulichen Strukturen von 30 Einrichtungen analysiert und umfangreiche Daten zur Orientierung der dort lebenden Bewohner erhoben. Es wurden fünf Wege innerhalb der Wohnbereiche identifiziert, die Bestandteil der Aktivitäten des täglichen Lebens sind und in allen Einrichtungen vorgefunden wurden. Durch Einschätzung der Pflegekräfte wurde bewertet, ob, bzw. wie gut, die Bewohner diese Wege zurücklegen können. Der Einfluss der unterschiedlichen baulichen Merkmale auf die resultierenden Orientierungswerte wurde mittels statistischer Signifikanztests überprüft. Die Ergebnisse zeigen, dass mit fortschreitender Demenz das Orientierungsvermögen sinkt. Gleichzeitig steigt die Abhängigkeit von der Ausprägung der baulichen Strukturen jedoch an. Signifikante Einflussfaktoren bestehen u. a. in der Bewohnerzahl, der Erschließungstypologie und der Ausformung der Gemeinschaftsflächen. Kleinere Einrichtungen begünstigen zwar die Orientierung, aber auch Wohnbereiche mit 25-30 Bewohnern können gute Werte erzielen, wenn sie eine geradlinige Horizontalerschließung über Flure, die keine Richtungswechsel beinhalten, aufweisen. Gleichartige Elemente, wie z.B. mehrere Wohn- und Essbereiche oder Cluster kleinerer Wohngruppen, schränken die Orientierung hingegen ein. Diese und weitere Erkenntnisse wurden in Gestaltungsempfehlungen überführt, die in der Versorgungspraxis bei der Planung sowie Umstrukturierung von Pflegeeinrichtungen angewendet werden können. Weiterhin wurden auf Grundlage im Krankheitsverlauf eingesetzter Orientierungsformen und –strategien Modelle des Orientierungsprozesses Demenzerkrankter entwickelt.

This thesis explores neural activity associated with processing of rotated alphanumeric characters, focusing particularly on linear and quadratic trend components of orientation-dependent activity. Choice of these components was driven by results of reaction-time (RT) studies; judging whether characters are normal or backward (parity task) typically elicit RTs that are linearly related to character disorientation, implying mental rotation of the characters to the upright, while judging whether they are letters or digits (categorisation task) elicits RTs related nonlinearly to disorientation, combining both linear and quadratic component, but not indicative of mental rotation. In Experiment 1 neural activity was monitored using fMRI while participants performed these tasks. In the next two experiments, neural processing was monitored with high-density EEG. In Experiment 2 participants performed the same two tasks, while in Experiment 3 they performed the category task and red-blue colour judgements. In Experiment 1, linear increases in fMRI activation were elicited only by the parity task and were observed in the posterior portion of the dorsal intraparietal sulcus and lateral and medial pre-supplementary motor areas, suggesting a fronto-parietal network underlying mental rotation. Experiment 2 showed that linear increases in parietal negativity between 350 and 710 ms only evident in the parity task, again indicating that mental rotation is only elicited by that task. Contrary to previous evidence, Experiment 2 indicated that both hemispheres may be involved in mental rotation, but rotation is faster in the right hemisphere than in the left hemisphere. Experiment 1 also showed that effects of orientation common to both tasks were best characterised by a quadratic trend, and were restricted to the supramarginal gyrus. This activation was interpreted as representing orientation-dependent shape recognition. Experiments 2 and 3 also revealed orientation-dependent neural activity at three distinct stages prior to mental rotation. First, on the P1 component, there was a difference between oblique and vertical orientations, suggesting the extraction of orientation based on axis of elongation. Next, orientation affected the N1 component, with longer latencies and larger amplitudes with misorientation, and smaller effects for inversion than for intermediate angular rotations. Finally, changes in orientation affected the P2 component differently for the parity and category tasks, probably signalling the perception of orientation relative to a parity-defined memory representation, and serving as a preparation for mental rotation. These experiments identify both the orientation-specific neural processing that occurs prior to the onset of mental rotation, and the subsequent neural correlates of mental rotation itself. / Top Achiever Doctoral Scholarship, University of Auckland Doctoral Scholarship, The New Zealand Neurological Foundation, University of Auckland Research Fund (Project numbers: 3607199, 3605876 3604420)

This thesis explores neural activity associated with processing of rotated alphanumeric characters, focusing particularly on linear and quadratic trend components of orientation-dependent activity. Choice of these components was driven by results of reaction-time (RT) studies; judging whether characters are normal or backward (parity task) typically elicit RTs that are linearly related to character disorientation, implying mental rotation of the characters to the upright, while judging whether they are letters or digits (categorisation task) elicits RTs related nonlinearly to disorientation, combining both linear and quadratic component, but not indicative of mental rotation. In Experiment 1 neural activity was monitored using fMRI while participants performed these tasks. In the next two experiments, neural processing was monitored with high-density EEG. In Experiment 2 participants performed the same two tasks, while in Experiment 3 they performed the category task and red-blue colour judgements. In Experiment 1, linear increases in fMRI activation were elicited only by the parity task and were observed in the posterior portion of the dorsal intraparietal sulcus and lateral and medial pre-supplementary motor areas, suggesting a fronto-parietal network underlying mental rotation. Experiment 2 showed that linear increases in parietal negativity between 350 and 710 ms only evident in the parity task, again indicating that mental rotation is only elicited by that task. Contrary to previous evidence, Experiment 2 indicated that both hemispheres may be involved in mental rotation, but rotation is faster in the right hemisphere than in the left hemisphere. Experiment 1 also showed that effects of orientation common to both tasks were best characterised by a quadratic trend, and were restricted to the supramarginal gyrus. This activation was interpreted as representing orientation-dependent shape recognition. Experiments 2 and 3 also revealed orientation-dependent neural activity at three distinct stages prior to mental rotation. First, on the P1 component, there was a difference between oblique and vertical orientations, suggesting the extraction of orientation based on axis of elongation. Next, orientation affected the N1 component, with longer latencies and larger amplitudes with misorientation, and smaller effects for inversion than for intermediate angular rotations. Finally, changes in orientation affected the P2 component differently for the parity and category tasks, probably signalling the perception of orientation relative to a parity-defined memory representation, and serving as a preparation for mental rotation. These experiments identify both the orientation-specific neural processing that occurs prior to the onset of mental rotation, and the subsequent neural correlates of mental rotation itself. / Top Achiever Doctoral Scholarship, University of Auckland Doctoral Scholarship, The New Zealand Neurological Foundation, University of Auckland Research Fund (Project numbers: 3607199, 3605876 3604420)