A New Paradigm for the Study of Cognitive Flexibility in Children and Adolescents: The "Virtual House Locomotor Maze" (VHLM)

Abstract

Classical neuropsychological assessments are designed to explore cognitive brain functions using paper-and-pencil or digital tests. The purpose of this study was to design and to test a new protocol named the "Virtual House Locomotor Maze" (VHLM) for studying inhibitory control as well as mental flexibility using a visuo-spatial locomotor memory test. The VHLM is a simple maze including six houses using the technology of the Virtual Carpet Paradigm™. Ten typical development children (TD) were enrolled in this study. The participants were instructed to reach a target house as quickly as possible and to bear in mind the experimental instructions. We examined their planning and replanning abilities to take the shortest path to reach a target house. In order to study the cognitive processes during navigation, we implemented a spatio-temporal index based on the measure of kinematics behaviors (i.e., trajectories, tangential velocity and head direction). Replanning was tested by first repeating a path chosen by the subject to reach a given house. After learning this path, it was blocked imposing that the subject inhibited the learned trajectory and designed a new trajectory to reach the same house. We measured the latency of the departure after the presentation of each house and the initial direction of the trajectory. The results suggest that several strategies are used by the subjects for replanning and our measures could be used as an index of impulsivity.

Keywords: cognitive control; executive functions; locomotor protocol; replanning; spatial navigation; visuospatial abilities.

Figure 1

(A) The representation of the experimental setup: (a) control desk location where the experimenter runs the experiment, (b) departure point, (c) two HTC Vive cameras, (d) the video projector. (B) 3D motion sensors motion-tracker. (a) one handheld 3D motion sensor is adapted to a bike helmet and is worn on the participant's head and (b) the second handheld 3D motion sensor is attached to the belt which worn on the participant's waist.

Figure 2

The Virtual Maze layout. (A) The left image shows a target house highlighted in green. The same house was shown 5 times for inducing an overlearned trajectory. (B) The right image shows a target house highlighted in green and the obstacles blocking access to the house by the shortest paths. This induced the necessity to replan the overlearned trajectory.

Figure 3

The global navigational array in the X and Y- axis coordinates. (A) The “c” represents de corners, the “h1”, “h2”, “h3”, etc. represent the house order presented to the participant and the “d” represents de Start point. (B) Representation of the projection on the floor including the houses and the start point.

Figure 4

Representation of the Learning and the Replanning phase for a single participant : (A) Trajectories and (B) tangential velocities for the learning. (C) Trajectory and (D) tangential velocity for the replanning phase for the first house. The red arrows represent the direction of the trajectories for the replanning phase showing a new direction (ND) adapted reconfiguration during the replanning.

Figure 5

Representation of the computing tangential velocity and latency (Lambda, λ) of one participant during a trail in the Learning phase. In the X-axis, the zero corresponds to the moment when the house was lit on the ground indicating “GO” signal. The time of real departure of the subject was computed when the tangential velocity was above the threshold of 30 cm/sec. The “λ” is the delay between the “GO” signal and the velocity exceeding the threshold.

Figure 6

Boxplot of latency in Sec by trials (Leaning and replanning). Box = 25th and 75th Percentiles; bars = min and max values.

Figure 7

(A) An example of a trajectory for the learning phase. (B) An example of a trajectory for the replanning phase. The red arrows represent the head direction of the trajectories for each phase.

Figure 8

Trajectories replanning examples. (A) Departure to previous learned direction (PLD) during replanning before the treatment. (B) Departure to a new direction (ND) after the treatment. The red arrows represent the head direction of the trajectories during the replanning phase.