UC San Diego

The study behavioral phenomena and the brain states which accompany these behaviors has a long history. The fields of neuroscience and behavioral psychology have, for over 100 years, utilized structured mazes in their work in order to probe how animals choose to navigate them, and how neuron activity reflects navigational features of the environment. This dissertation proposes that appreciating similar places within an environment requires a structurally complex environment to appreciate. Evidence that structural complexity ought to elicit novel neural and behavioral phenomena is substantial. There is evidence that subiculum (SUB) neurons respond in a spatial manner similarly across different environments that share general structural complexity, and present unique directional tuning only on structured mazes. There is also evidence that less explicit structure in an open environment can drastically modulate activity in posterior parietal cortex (PPC) neurons. Both of these brain regions lay along an anatomical circuit connecting the hippocampal formation (HPC) to motor-output regions of the brain. Furthermore it is known that alternation behavior (AB), while reliable, is readily modulated by environmental factors in simple structures. To address deficiencies in investigating these systems this dissertation employs both a structured maze, the triple-T, alongside a working memory task which allows for the animal to self-organize a strategy; thus providing structure in two forms, one explicit with the maze, and one implicit with the reward contingencies. Unique representations of place-analogies, and structural route-similarity are reported from SUB and PPC respectively. These reports alongside a report of AB being organized by spatial location provide a functional framework for the utility of appreciating similar places in complex spaces. This dissertation describes the neural correlates of brain regions anatomically crucial to a space-to-action circuit while animals are navigating on a structurally complex environment. We discovered novel spatial representations in neuron populations linking HPC to motor-associated regions of the brain. We also discovered novel behavioral organization elaborating on well-known AB studies. Altogether these data show the importance of probing these systems with sufficiently complex structure in order to get a deeper understanding of these systems.