In daily life, both animals and humans are often faced with the task of returning to previously visited locations. In many cases, an organism must be able to (1) establish a directional frame of reference and (2) determine location based on surrounding cues in order to solve this problem. Moreover, successful navigation is generally thought to rely on how an organism learns and uses the metric relationships between various locations in its environment. This thesis examines various factors that affect the way animals encode and use metric information in their environment, both to orient and to navigate. A transformation approach is used to determine what aspects of metric information are learned and/or preferred. Additionally, this thesis follows a comparative approach in order to examine similarities and differences among species. In chapter 2, I show that two closely related species of chickadees differently use geometric and featural information when establishing a directional frame of reference. I suggest that ecological factors, but not rearing condition, affect the way that chickadees preferentially use metric or featural information to orient. In chapter 3, I used a similar paradigm to show that a pre-existing directional frame of reference can interact with rats’ use of metric cues to navigate. More specifically, chapter 3 shows that experience gained through training procedures affects the way that rats use metric information in a navigation task. Chapter 4 expands upon this idea, and shows that pigeons encode directional metric differently based on their past experience. Finally, in chapter 5, I examined the flexibility of use of metrics by comparing how search strategies of human adults and children can change based on a goal’s proximity to an edge. To summarize, this thesis shows that use of metric information is malleable and situation-specific and can be affected by a variety of factors including ecology, past experience and boundary information.

No description available.

Neurologically healthy individuals misbisect their visual space by erring towards the left. This misreprentation has been attributed to the right hemisphere dominance in processing of spatial information. Lateral biases are thought to emerge as behavioural outcomes of cognitive processing, mainly attention. Recently, attention mechanisms have been reported to be closely inter-related to memory systems, where attention directs what will be remembered and memory impacts where attention is directed. Although spatial biases attributed to attention have been widely accepted, the claim that memory exhibits similar biases has been more controversial. Recent research shows that recall of representations is biased towards the left side of space, indicating that lateral asymmetries may not necessarily be limited to perceptual and attentional mechanisms, but may extend to memory mechanisms as well. The purpose of this work is to understand better the relationship between lateral biases within working memory and attention interactions. Two approaches were considered. First, working memory, as defined by the representations and operations related to manipulate the representations, used time delay and visual load. Second, backward masking was used to control the relative formation of the working memory trace, which strengthens with recurrence of the visual stimuli and is through to progress from attention to working memory. To explore these two theoretical avenues, a novel task was constructed. Two circular arrays were presented at the top and bottom of the computer screen. These arrays were composed of six individual discs of varying shade. Hence, the overall array represented a greyscale gradient, where discs on one lateral side were darker compared to the middle discs and the other lateral side. For example, if two darkest discs were presented on the left side, the lightest discs were presented on the right side. Such array was presented with its left/right mirror reversed image. In this example, the second array was with the lightest discs on the left side and growing progressively darker, with darkest discs on the right side. Such presentation requires the participants to integrate the array of individual discs into an overall representation to perform a brightness judgement and select the array seemingly darker. A total of six behavioural studies addressed the two theoretical approaches. The first approach, to determine the impact of inter-stimulus time interval and visual load on lateral asymmetries, was addressed in four experiments. The findings indicated that participants were able to integrate the discrete disks into an overall array. Participants exhibited an overall leftward bias similar to that obtained in attention tasks, where they selected an array to be overall darker when the darkest disks were presented on the left side of the array. Furthermore, these biases increased the most when the stimuli were presented in the lower half of the computer screen, consistent with the lower visual field. Conversely, stimuli presented to the upper half of the screen elicited a rightward bias, which is consistent with the upper visual field. Stronger biases were observed when the stimulus noise, in the form of black, white and grey pixels, was relatively low and weaker biases were attained with a relatively high noise levels. In the second study, the findings showed that the magnitude of upper and lower visual field biases shows dependence on the vertical and lateral stimulus manipulation within these fields. Upper-left, lower-right interactions indicate that biases may not simply rely on the horizontal and vertical dimensions, as previously thought, but also on the relative spatial distribution of stimuli within these dimensions. The third study, which used the standard rectangular greyscale stimuli, revealed that visual load does not impact the lateral biases, but shows to impact the upper and lower visual field processing. Further, time interval between stimulus presentation and response, extended past 1 second eliminated lateral and vertical biases. The remaining two studies investigated lateral asymmetries within working memory by selectively manipulating the formation of working memory trace using backward masks. The presence of a mask, following a stimulus, inhibits the memory trace formation for that stimulus. Conversely, if no mask is presented following the stimuli, the memory trace is permitted to form within working memory. Again, using the circular array task, participants were required to select the overall darker array while retaining either a shade of position information from the array within their working memory. Findings showed increased rightward biases when memory trace was permitted to form with longer inter-stimulus (3 sec) time interval, as compared to shorter (0 to 1 sec) time interval. In the last study, the participants were required to make brightness judgement while maintaining either a position or shade information within working memory to determine whether previously acquired information, which does not serve as a cue, impact the brightness judgement task. Rightward biases were evident when participants were required to maintain either a position or shade information relating to the array, but did not provide any cue-type of information, which could facilitate performance. Rightward biases were stronger while retaining position information and completing the brightness task, hence indicating a spatial nature of the bias. As well, stronger rightward biases were obtained when the to-be-remembered position information was allowed to create a memory trace. Furthermore, recall accuracy of the position information was increased when the memory trace was permitted to form, indicating involvement of working memory processes. Overall, the data attained in this set of experiments can be interpreted using the activation-orientation model presented by Reuter-Lorenz (1990) indicating that this model may also be valuable when integrating working memory in addition to attentional processes.

The nervous system is a complex organ that functions in most metazoans to sense and respond to a constantly changing world. How the nervous system does this is a major focus of systems-level neuroscience. This dissertation investigates the neural basis of the sensorimotor transformation underlying a spatial orientation strategy in the nematode Caenorhabditis elegans. Motile organisms rely on spatial orientation strategies to navigate to environments that are conducive to organismal fitness and comfort, e.g. environments with the correct temperature, light level, or access to food and mates. As such, spatial orientation strategies as a class represent a key behavior common to most forms of life on earth. To explore the behavioral mechanism used by C. elegans for spatial orientation, we designed and manufactured a microfluidic device that breaks the feedback loop between self-motion and environmental change by partially restraining the animal. The device takes advantage of laminar flow at small scale to provide distinct environments across the dorsoventral undulation that constitutes locomotion in this animal without using a physical barrier. This device allowed us to conclude that worms use the change in chemical concentration sensed between lateral extremes of the locomotion cycle to direct forward locomotion toward a favorable stimulus, an orientation strategy termed klinotaxis. We then investigated the neuronal basis of this behavior using laser ablation, calcium imaging, and optogenetic stimulation. We found a minimal neuronal network for klinotaxis to sodium chloride including the ASE, AIY, AIZ, and SMB neuron classes that displays left/right asymmetry across the sensory neuron, interneuron, and motor neuron levels. We extended these results by ablating other neurons that have been implicated in klinotaxis in other studies. Finally, we imaged the ASE neurons during klinotaxis in microfluidic device and found that these neurons are active on the timescale of individual head swings. Additionally, we found anecdotal evidence that photostimulation of ASE neurons expressing the light sensitive ion channel Channel Rhodopsin (CHR2) is sufficient to stimulate klinotaxis behavior. This dissertation includes previously published co-authored material.

The purpose of this project is to design a computer program to help children understand a strategy for changing vantage points within an imagined space and gain knowledge of how spatial transformations work. The developed software, called Viewpoints, presents a virtual three-dimensional environment to be explored and modified by the user. Object and camera manipulations are illustrated through animation. Furthermore, the program was designed to have an intuitive interface and be easy to access. This should allow the software’s target audience of children to focus on the spatial orientation and spatial visualization aspects. A small study evaluated the software in terms of content, instructional design, technical quality, student use, and instructor use. The study provided valuable feedback on how to improve Viewpoints in the future. Information gathered suggests the issue of speed should be addressed and supplemental materials should be added.

Thesis (M.A.) - Carleton University, 2005. / Includes bibliographical references (p. 82-98). Also available in electronic format on the Internet.

The ability of the spatial orientation of the reptiles is not fully researched yet. It is unknown if reptiles use only simple types of navigation, for example cue learning (one key mark), or more difficult types, for example allothetic navigation (combination of marks) or cognitive map (mental representation of the area). The main aim of this thesis was examine the possibility of the spatial orientation in lizard leopard gecko (Eublepharis macularius) in modificated Morris water maze (MWM). Design of the experiments was based on Parallel Map Theory, a theory which describes using spatial information from more navigation frames. The leopard gecko preferences of orientation frames were tested . That means the ability to combinate the spatial information from the bearing maps (one mark and gradient) and the sketch maps (local marks). This ability is prerequisite for creating the integrated map. The research was also focused on the significance of the simple cue learning strategy and cognitive more difficult allothetic navigation for the orientation of leopard gecko. Leopard geckos can use the combination of information from the navigation frames, which indicate the possibility of integrated map creation. Usage of navigation strategies is individual. Keywords: reptiles, leopard gecko, spatial...

The domestic chick (Gallus gallus domesticus) has been widely used as an animal model to investigate spatial orientation and the neural mechanisms underlying this function. In all vertebrate species the hippocampus plays an essential role in spatial orientation. Since the hippocampus is a bilateral structure, it is important to investigate the specific role of the left and the right hippocampi in spatial processing. Although, the domestic chick has been often used as animal model to assess cognitive lateralization, the involvement of the left and the right hippocampal formation in spatial orientation has been poorly investigated in this model. Behavioral studies using monocular eye occlusion have shown that in chicks the left eye-system (right hemisphere) is involved in the elaboration of spatial relational information, while the right eye-system (left hemisphere) processes local information. However, while visual lateralization in chicks had been traditionally considered to be induced by embryonic light exposure, recent studies suggest the presence of structural and behavioural asymmetries also in dark-incubated chicks. Thus, the main aim of this thesis was to test the lateralization of hippocampal functions in dark incubated chicks, both in spatial and non-spatial tasks. In the first study dark-incubated chicks were trained to orient in a large circular arena using spatial relational information provided by free-standing objects. Once chicks reached a learning criterion they were tested binocularly or under a monocular eye-occlusion condition. This study provided the first demonstration that domestic chicks are able to orient by relational spatial information provided by free-standing objects, in binocular vision conditions. However, if either one of the two eyes was occluded, chicks failed the orientation task. These results show that at least in dark-incubated chicks binocular integration is needed to solve this spatial orientation task. We also investigated if chicks have a preference to orient by local or spatial information provided by free-standing objects and if this ability is influenced by eye occlusion. Chicks preferred to use local over spatial cues to orient, both in binocular and monocular conditions (independently of which eye was occluded). These results indicate that local cues are processed by both eye-systems and do not require access to information from both eyes, contrary to relational spatial cues. Using the same setup, in the second study we directly investigated the involvement of chicks’ left and right hippocampal formation during orientation by free-standing objects. For this purpose we performed an immunohistochemical staining of the immediate early gene product c-Fos (a neural activity marker). Two independent groups of dark-incubated chicks were trained to find food in the large circular arena and the level of hippocampal activation was compared between the two groups. One group was trained to orient exclusively by local cues, while the other was orienting by spatial relational information provided by free-standing objects. This revealed selective activation of the right hippocampus during orientation by spatial relational information in dark-incubated chicks. While monocular occlusion has often been used to test lateralization of spatial functions in chicks, it is still unclear whether this manipulation affects hippocampal activation. The aim of the third study was to clarify this issue, by exposing dark-incubated chicks to a novel environment in conditions of monocular occlusion or binocular vision. Activation of the hippocampal formation was once again measured by c-Fos expression. Exposure to a novel environment is known to trigger hippocampal activation in different animals, including domestic chicks. As expected, exposure to the novel environment activated the hippocampus in binocular vision conditions. However, if either one of the eyes was occluded, the hippocampal c-Fos expression did not rise above what observed in the baseline condition (chicks maintained in a familiar environment). Thus, successful hippocampal response to a novel environment requires input from both eyes. Our results also suggest that monocular occlusion equally affects the left and the right hippocampus. Overall, access to information from both eyes plays a crucial role for the acquisition of a spatial map of a novel environment, in line with the behavioral results of the first study. Moreover, a task independent lateralization effect, with higher c-Fos expression in the left compared to the right hippocampus, could be observed in all the experimental conditions. This confirms the presence of neuroanatomical lateralization in dark-incubated chicks. The last study investigated whether chicks’ hippocampus would also respond to novel social stimuli, in line with the activation observed in this structure after exposure to a novel environment. Only few studies have directly investigated the involvement of birds’ hippocampal formation in social functions. Here, the hippocampal activation was compared between chicks exposed to an unfamiliar conspecific vs. chicks exposed to a familiar one. We found that the ventral and dorsomedial portion of the right hippocampus of dark-incubated chicks responds to an unfamiliar individual. This provides the first demonstration of hippocampal sensitivity to social novelty in birds. Overall the studies performed in this thesis indicate a selective lateralized involvement of domestic chicks’ hippocampal formation not only in spatial, but also in social functions.

This diploma thesis summarizes recent knowledge about body scheme, spatial orientation and their change in context of chronic pain. The purpose of this work is to find out if chronic pain negatively affects the body scheme and spatial orientation. The thesis includes a comparative analysis of experimental measurements between the patients with Failed Back Surgery Syndrome and healthy control group. The analysis compares tasks based on spatial orientation and body scheme tests. Results show the patients' group having lower results in body scheme related tests, showing a noticeable disparity compared to the control group's test scores. These results were further supported by portion of spatial orientation based tasks, where patients' group again performed at significantly lower level than the control group. In conclusion, our thesis, along with other academic works, states that there is a correlation between chronic pain, disrupted body scheme and spatial orientation. However, at the present time it could not be determined whether the pain precedes the effect of disrupted body scheme or vice versa. Powered by TCPDF (www.tcpdf.org)

The aim of this diploma thesis is to evaluate spatial orientation in the patients after vestibular schwannoma surgery. In the theoretical part, there are summarized the facts about vestibular system; there is described the clinical picture of unilateral vestibular dysfunction and the field of vestibular schwannoma and spatial orientation in general. In the practical part, we performed the investigation of the spatial orientation using the Blue Velvet Arena System and posturography using the platform Balance Master® System. The purpose of the practical part was to find out, whether unilateral vestibular dysfunction in patients after vestibular schwannoma surgery has the impact on spatial orientation and to what extent is the postural stability influenced in patients identified for surgery and in patients after vestibular schwannoma surgery. Powered by TCPDF (www.tcpdf.org)