Graduate School of Systemic Neurosciences - Digitale Hochschulschriften der LMU

Animals require cognitive maps for efficiently navigating in their natural habitat. Cognitive maps are a neuronal representation of their outside world. In mammals, place cells and grid cells have been implicated to form the basis of these neuronal representations. Place cells are active at one particular location in an environment and grid cells at multiple locations of the external world that are arranged in a hexagonal lattice.

This thesis proposes a new approach to investigate insight problem solving. Introducing magic tricks as a problem solving task, we asked participants to find out the secret method used by the magician to create the magic effect. Based on the theoretical framework of the representational change theory, we argue that magic tricks are ideally suited to investigate insight because similar to established insight tasks like puzzles, observers’ prior knowledge activates constraints. In order to see through the magic trick, the constraints must be overcome by changing the problem representation. The aim of the present work is threefold: First, we set out to provide a proof of concept for this novel paradigm by demonstrating that it is actually possible for observers to gain insight into the magician’s secret method and that this can be experienced as a sudden, insightful solution. We therefore aimed at showing that magic tricks can trigger insightful solutions that are accompanied by an Aha! experience. The proposed paradigm could be a useful contribution to the field of insight research where new stimuli beyond traditional puzzle approaches are sorely needed. Second, the present work is aimed at contributing to a better understanding of the subjective Aha! experience that is currently often relied on as important classification criterion in neuroscientific studies of insight, yet remains conceptually vague. The new task will therefore be used to further elucidate the phenomenology of the Aha! experience by assessing participants’ individual solving experiences. As a third question, we investigated the influence of insight on memory. A positive impact of insight on subsequent solution recall is often implicitly assumed, because the representational change underlying insightful solutions is assumed to facilitate the retention of solution knowledge, yet this was never tested. A stimulus set of magic tricks was developed in collaboration with a professional magician, covering a large range of different magic effects and methods. After recording the tricks in a standardized theatre setting, pilot studies were run on 45 participants to identify appropriate tricks and to ensure that they were understandable, surprising and difficult. In the main experiment, 50 participants watched the final set of 34 magic tricks, with the task of trying to figure out how the trick was accomplished. Each trick was presented up to three times. Upon solving the trick, participants had to indicate whether they had found the solution through sudden insight (i.e. with an Aha! experience) or not. Furthermore, we obtained a detailed characterization of the Aha! experience by asking participants for a comprehensive quantitative (ratings on a visual analogue scale with fixed dimensions) and qualitative evaluation (free self-reports) which was repeated after 14 days to control for its reliability. At that time, participants were also required to perform a recall of their solutions. We found that 49% of all magic tricks could be solved and specifically, that insightful solutions were elicited in 41.1% of solved trials. In comparison with noninsight solutions, insightful solutions (brought about by representational change) were more likely to be correct and reached earlier. Quantitative evaluations of individual Aha! experiences turned out to be highly reliable since they remained identical across the time span of 14 days. Qualitatively, participants reported more emotional than cognitive aspects. This primacy of positive emotions was found in qualitative as well as in quantitative evaluations, although two different methods were used. We also found that experiencing insight leads to a facilitated recall of the respective solutions since 64.4% of all insight solutions were recalled correctly, whereas only 52.4% of all noninsight solutions were recalled correctly after a delay of 14 days. We demonstrated the great potential of our new approach by providing a proof of concept for magic tricks as a problem solving task and conclude that magic tricks offer a novel way of inducing problem solving that elicits insight. The reliability of individual evaluations of Aha! experiences indicates that, despite its subjective character, it can be justified to use the Aha! experience as a classification criterion. The present work contributes to a better understanding of the phenomenology of the Aha! experience by providing evidence for the occurrence of strong positive emotions as a prevailing aspect. This work also revealed a memory advantage for solutions that were reached through insight, demonstrating a facilitating effect of previous insight experiences on the recall of solutions. This finding provides support for the assumption that a representational change underlying insightful solving experiences leads to long-lasting changes in the representation of a problem that facilitate the retention of the problem’s solution. In sum, the novel approach ...

’Gain-field-like’ tuning behavior is characterized by a modulation of the neuronal response depending on a certain variable, without changing the actual receptive field characteristics in relation to another variable. Eye position gain fields were first observed in area 7a of the posterior parietal cortex (PPC), where visually responsive neurons are modulated by ocular position. Analysis of artificial neural networks has shown that this type of tuning function might comprise the neuronal substrate for coordinate transformations. In this work, neuronal activity in the dorsal medial superior temporal area (MSTd) has been analyzed with an focus on it’s involvement in oculomotor control. MSTd is part of the extrastriate visual cortex and located in the PPC. Lesion studies suggested a participation of this cortical area in the control of eye movements. Inactivation of MSTd severely impairs the optokinetic response (OKR), which is an reflex-like kind of eye movement that compensates for motion of the whole visual scene. Using a novel, information-theory based approach for neuronal data analysis, we were able to identify those visual and eye movement related signals which were most correlated to the mean rate of spiking activity in MSTd neurons during optokinetic stimulation. In a majority of neurons firing rate was non-linearly related to a combination of retinal image velocity and eye velocity. The observed neuronal latency relative to these signals is in line with a system-level model of OKR, where an efference copy of the motor command signal is used to generate an internal estimate of the head-centered stimulus velocity signal. Tuning functions were obtained by using a probabilistic approach. In most MSTd neurons these functions exhibited gain-field-like shapes, with eye velocity modulating the visual response in a multiplicative manner. Population analysis revealed a large diversity of tuning forms including asymmetric and non-separable functions. The distribution of gain fields was almost identical to the predictions from a neural network model trained to perform the summation of image and eye velocity. These findings therefore strongly support the hypothesis of MSTd’s participation in the OKR control system by implementing the transformation from retinal image velocity to an estimate of stimulus velocity. In this sense, eye velocity gain fields constitute an intermediate step in transforming the eye-centered to a head-centered visual motion signal.Another aspect that was addressed in this work was the comparison of the irregularity of MSTd spiking activity during optokinetic response with the behavior during pure visual stimulation. The goal of this study was an evaluation of potential neuronal mechanisms underlying the observed gain field behavior. We found that both inter- and intra-trial variability were decreased with increasing retinal image velocity, but increased with eye velocity. This observation argues against a symmetrical integration of driving and modulating inputs. Instead, we propose an architecture where multiplicative gain modulation is achieved by simultaneous increase of excitatory and inhibitory background synaptic input. A conductance-based single-compartment model neuron was able to reproduce realistic gain modulation and the observed stimulus-dependence of neural variability, at the same time. In summary, this work leads to improved knowledge about MSTd’s role in visuomotor transformation by analyzing various functional and mechanistic aspects of eye velocity gain fields on a systems-, network-, and neuronal level.