Affiliations: Faculty of Electrical, Biomedical and Mechatronics Engineering, Qazvin Brach, Islamic Azad University, Qazvin, Iran. E-mail: [email protected]
Abstract: Existence of allocentric and egocentric systems for human navigation, mediating spatial and response learning respectively, has been discussed so far. It is controversial whether navigational strategies and their underlying learning systems and, accordingly, the activation of their associate brain areas are independent/parallel or whether they functionally/causally interact in a competitive or in a cooperative manner to solve navigational tasks. Insights of neural networks involved in reward-based navigation attributed to individual involvement or interactions of learning systems were searched. This paper characterizes the neuronal interactions by constructing generative neural models and investigating their functional and effective connectivity patterns. A computer first-person virtual reality environment was constructed to simulate a navigation task within a naturalistic large-scale space wherein participants were rewarded for using either a place or response or mixed strategy within different stages. First, functional analyses were fulfilled to evaluate neural activities via mapping the brain activation and making statistical inference. Effects of interest of spatial and response learning/retrieval and their competition and cooperation were investigated. The optimal generative model was then estimated using dynamic casual modeling to quantify effective connectivities within the network. This analysis revealed that how experimental conditions in support of strategies’ competition and cooperation modulate the underlying network. Results suggest that when navigational strategies cooperated, there were statistically significant functional and effective connectivities between hippocampus and striatum. However, when the strategies competed effective connections were not established among these regions. Instead, connections between hippocampus/striatum and prefrontal cortex were strengthen. It can be inferred that a kind of dynamical reconfigurations occur within a network responsible for navigation when strategies interact either cooperatively or competitively. This supports the adaptive causal organization of brain when it is engaged within a goal directed behavior.