Navigating in an environment means not only orienting. Beside the orienting process, it seems to involve also planning, that is another process considered as a form of problem solving. A navigation through the environment without a plan may be not efficient as it is. Despite these consideration, very few studies drew attention on interaction between planning and wayfinding (i.e., finding a way in the environment we are navigating in), using a planning task within a wayfinding task in either a real or a simulated environment. In cognitive psychology, visuospatial planning process has been studied using the “Traveling Salesperson Problem” (TSP), which simulates a salesperson who has to achieve all the errands displayed on a map in the shortest route and time. In the present work, a 3D version task developed from the Maps task (a 2Dcomputerized task based on TSP paradigm) was used: subjects should navigate by means of a computer keyboard into a 3D simulation of a regular grid of gangways, aiming to collect all the subgoals. During the execution of the task, rTMS stimulation at 1 Hz of either the parietal (P3 or P4) and frontal (F3 or F4) lobes was hypothesized to induce a worsening in the performance only if these areas are involved in the task. Since both planning and wayfinding are required to efficiently execute the task, a network of cortical areas has been hypothesized to be their neural substrate. In particular, we hypotesized that: a) rTMS on PFC should disturb the execution of the plans; b) inhibition of PPC should interfere with plan creation in its visuospatial and representational components; c) gender differences may emerge from the stimulation of the 2 hemispheres and areas. Hypotheses were confirmed by several results: TMS generally worsened women performance when stimulating right PPC, while men performed worse when left PFC was stimulated. In general, males exhibited shortest paths, execution and planning time with respect to females. Planning during a wayfinding task, therefore, seems to involve a cerebral network based on PPC and PFC. An explanation for the role of the 2 regions is proposed: PPC is mainly involved in generating a plan based on the environment representation, while PFC monitors the execution of the plan and, if needed, operates a switch to a new plan. Moreover, sexual differences are found to modulate the distribution of these processes.
Authors: Chiara Saracini, Daniela Basso, Marta Olivetti Belardinelli
Publish Year: 2008
