The development of a neural wayfinding mechanism: How children and adolescents process landmarks.

Successful navigation is often facilitated by the presence of objects along the
route. However, not all objects equally support navigation. In order to
navigate successfully, we need to distinguish between relevant, irrelevant and
ambiguous information. Previous imaging studies in adult human beings provided
evidence for the existence of a highly specific neural network that responds to
the navigational relevance of objects. More specifically, the parahippocampal
gyrus (PHG) (major component of the medial temporal lobe (MTL)) responds to
objects that are relevant for successful navigation whereas the right middle
frontal gyrus (major component of the prefrontal cortex (PFC)) responds to
ambiguous information along the route.
From a developmental perspective, surprisingly little is known about spatial
navigation. Even less is known about the development of neural circuitries that
support this ability. Recent neuroimaging studies revealed that MTL and PFC
regions develop late into adolescence. On the basis of this result, it is
hypothesized that MTL and PFC maturation is a limiting factor in the use of
landmark information. The proposed study aims to test this hypothesis.

The aim of this study is to examine the neural correlates of landmark
processing in children and adolescents. We are particularly interested in the
developmental trajectory of a specific brain network that automatically
distinguishes between relevant, irrelevant and ambiguous information along the
route.

The proposed study has a quasi experimental design. The experiment will be
divided into two parts. Those parts will take place on two consecutive days.
During the first visit, the participant will be administered the Raven Standard
Progressive Matrices (R-SPM) test. The R-SPM assesses cognitive functioning by
means of a visuospatial task that requires participants to identify the missing
item that completes the stimulus pattern. In a mean while, parents will fill
out the child behavior checklist to screen the child for psychiatric
conditions.
The second day is divided into three parts: A study phase outside the scanner,
a recognition phase inside the scanner and a navigation phase outside the
scanner. During the study phase, the participant watches a film sequence of a
guided tour in a virtual museum. The museum has 120 objects at its disposal,
all of which are placed on tables along the wall. Each object is assigned to
one of four conditions. In condition 1, the object appears twice at different
locations that are relevant for successful navigation (i.e. decision point). In
condition 2, the object appears twice at different locations that are
irrelevant for successful navigation (i.e. non-decision point). In condition 3,
the object appears once at a decision point. And in condition 4, the object
appears once at a non-decision point. Participants are instructed to attend to
the route and the objects along the route. When the study phase is completed,
the participant is required to perform a recognition task of the objects inside
the scanner. During this task, functional images of the whole brain are
acquired. Finally, the participant will perform a navigation task outside the
scanner.

We aim to investigate the development of a neural network that has shown to
support spatial navigation in adults. We will therefore include children and
adolescents in the proposed study. There are no known risks associated with
participation in the study.