![]() Interestingly, these memorized operations can be overlearned to such a degree they become habits. Patients with striatal perturbations have a difficult time retracing the circle relative to control subjects ( Paquette et al. In humans an easy way of assessing this behavior is to have subjects walk around a circle and then retrace the circle when blindfolded. In route-based navigation, an organism follows a path with the order of turns remembered as a set of specific rules, such as straight-left-right-left-left-that is, which direction to turn when it reaches specific signposts or moves in a specific direction for a given number of steps. Route-based navigation relies on internal cues of rate of movement, turns, and signposts, whereas path integration relies on these but involves an additional attribute, vector addition. Egocentric navigation generally refers to the ability to navigate by internal self-movement cues, but a further distinction can be made by dividing egocentric navigation into route-based and path integration. By contrast, allocentric navigation is disabled by the absence of visual cues.Įgocentric navigation and path integration have been used interchangeably by some, whereas others distinguish between them. Egocentric navigation can operate in darkness, indicating that visual cues are not essential for this method of navigating, although in the absence of visual cues egocentric navigational accuracy is reduced. A landmark provides relational information as to where the organism is compared with other landmarks, whereas a signpost is a marker of where to change direction along a path but does not give relational information. Signposts are different than landmarks in that a landmark is farther away and a signpost is close and signposts and landmarks convey different information. Egocentric wayfinding is characterized by the ability to navigate using internal cues (i.e., by feedback from limb movements for rate of movement, direction, turns, and sequence of turns), optokinetic flow as the organism moves past surrounding objects, and signposts. Allocentric wayfinding, also referred to as spatial navigation, is characterized by the ability to navigate using distal cues-that is, cues/landmarks located outside and at some distance from the organism. The dichotomous distinction is between allocentric and egocentric navigation. There are at least two distinct types of navigation, and perhaps three, depending on how it is defined. ![]() It is concluded that, on balance, the MWM has more advantages than disadvantages and compares favorably with other allocentric navigation tasks. Experimental factors that apply generally to spatial navigation and to MWM specifically are considered. Evidence-based design improvements and testing methods are reviewed for both rats and mice. MWM advantages (little training required, no food deprivation, ease of testing, rapid and reliable learning, insensitivity to differences in body weight and appetite, absence of nonperformers, control methods for proximal cue learning, and performance effects) and disadvantages (concern about stress, perhaps not as sensitive for working memory) are discussed. In this article, several allocentric assessment methods for rodents are reviewed and compared with the MWM. Egocentric navigation involves the dorsal striatum and connected structures in humans this system encodes routes and integrated paths and, when overlearned, becomes procedural memory. This form of memory is assessed in laboratory animals in many ways, but the dominant form of assessment is the Morris water maze (MWM). Allocentric navigation involves the hippocampus, entorhinal cortex, and surrounding structures in humans this system encodes allocentric, semantic, and episodic memory. This capacity is encoded in the brain by two systems: one using cues outside the organism (distal cues), allocentric navigation, and one using self-movement, internal cues and nearby proximal cues, egocentric navigation. The ability to do this depends on learning and remembering locations. ![]() Maneuvering safely through the environment is central to survival of almost all species.
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