Protocol to investigate the gradual selection and deployment of goal-oriented search strategies during unsupervised navigation in mice

Abstract

The ability of rodents to effectively navigate in an environment is based on trial-and-error learning and flexible decision-making and can be analyzed via navigational trajectories. We present a protocol for studying the deployment of search strategies in mice using the Morris water maze. We describe steps for assigning mice to different maze variations and procedures for post-training tracking and analysis. This protocol represents an effective behavioral readout to probe brain networks involved in strategy deployment and goal-oriented behavior. For complete details on the use and execution of this protocol, please refer to Parrini et al.¹.

Keywords: behavior; cognitive neuroscience; neuroscience.

Graphical abstract

Figure 1

Strategy deployment in 4 different variations of the MWM Strategy deployment plots for position (A, n = 12), chaining (B, n = 11), radius (C, n = 10), and random (D, n = 6) maze. Bars represent standard error. Figure reprinted and adapted with permission from Parrini et al.

Figure 2

Schematic representation of the MWM pool with definition of swimming areas in the tracking system 1, closer wall zone; 2, annulus; 3, target area; 4, platform; 5, goal corridor. The dashed lines represent the virtual division of the pool in 4 quadrants and the creation of 4 fictive cardinal points. These will be used as entry location of mice in the pool.

Figure 3

Classification and distribution of strategies in the position maze (A) Schematic of main searching strategies and corresponding substrategies The red lines and circles refer to the classification criteria as described in Figure 1. T, thigmotaxis; G1, global search 1; G2, global search 2; S1, directed search; S2, scanning in quadrant; S3, focal search; S4, direct swim. (B) Substrategy deployment during position maze training (n = 12). Figure reprinted and adapted with permission from Parrini et al.