Maps and memories of space in the human brain

Roppelt, Christopher (2020): Maps and memories of space in the human brain. Dissertation, LMU München: Graduate School of Systemic Neurosciences (GSN)

Abstract

Mammalian navigation is mostly studied in rodents and humans. Due to ethical and methodological constraints, rodent research so far primarily targeted the neurophysiological mechanisms of navigation, while navigation studies in humans predominantly focused on navigational behavior and the cognitive processes involved in it. Although basic mechanisms of navigation seem well preserved across rodents and humans in general, human and rodent navigation also differ substantially in several aspects and it is not obvious how particular findings translate across both species. As a consequence, for many aspects of navigation, we do not know how processes on the cognitive level can be attributed to those on the cellular level, and, eventually, how particular navigation behavior can be causally related to neural activity. This knowledge gap is addressed in this thesis with two studies that extend our understanding of how findings from rodents and humans translate across both species. To this end, a framework was developed that combines human navigation in landmark-sparse virtual environments that resemble the open-field setups typically used to study spatially tuned neurons in rodents. Applying this framework, the first study presented in this thesis separates passive and active components during navigation, and investigates how varying navigational and spatial memory demands impact participants' brain activity. The results suggest that, first, certain brain regions primarily known for perception of static scenes are recruited during passive navigation, and also contribute information processing specifically relevant for active navigation; and that, second, the anterior medial hippocampus provides a coherent spatial representation of the current environment that is dependent on spatial memory. Using a similar setup, the second study investigates participants' spatial representation in more detail. The results show that, first, a model inspired by electrophysiological findings in rodents that explains location memory as a function of proximity to the environment's boundaries generally matches participants' behavior in a similar open-field environment; that, second, the model's explanatory power may be further improved when, in addition to the precision, also the accuracy of participants' location memory is considered; and that, finally, in a quadratic open-field environment, the diagonals also impact participant's spatial orientation and location memory. The findings reported in this thesis demonstrate that the framework applied in both studies allows for a detailed investigation of human navigation behavior, and the cognitive processes associated with it. It furthermore increases comparability of findings between human and rodent navigation, and may eventually help to better understand how neurophysiological processes are transformed into navigation behavior.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: Human,Brain,Cognition,Space,Memory
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 570 Biowissenschaften, Biologie
• Fakultäten: Graduate School of Systemic Neurosciences (GSN)
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 15. Juli 2020
• 1. Bericht­erstatter:in: Flanagin, Virginia