No representation of allocentric space has been found in the
No representation of allocentric space has been found in the"No representation of allocentric space has been found in the brain"
Critically evaluate this statement.
The question of how animals and humans navigate is a fundamental research problem upon which there has been much experimentation and debate, and so it is necessary to refine the title to a specific point. As Tolman (1948) established that rats can solve spatial problems too complex for a purely stimulus-response system to solve, and that therefore some kind of neural map is necessary for navigation, this essay will basically address the question of whether the brain forms an allocentric (which is independent of the organism) or an egocentric (based on the organism's own perception of the surroundings) view of the environment. For the purpose of simplicity this essay will concern itself with only the brain of a rat.
This essay will thus discuss the evolution of relevant behaviourist and neurophysiological theories, the most important being O'Keefe (1991); Muller, Kubie, Bostock, Taube and Quirk (1991); and Rolls (1991).
The behaviourist theories proposed that a reward or aversive object/event will motivate a rat to move towards or away from the location along a reward gradient, and this has been shown to be the case with rats in a maze situation (O'Keefe, 1983). Indeed, this situation does not require the rat to have a concept of absolute space; it may depend on associations between cues and responses which are provided by the maze structure itself. However, O'Keefe & Nadel (1978) identified spatial behaviours which they argued would require the existence of an allocentric map: detection of changes within the environment; navigation to the goal from a different starting location; and perhaps most importantly detour behaviour, which required the adaptation of novel behaviour to find the goal after the usual route had been blocked in some way.
Further support was added by Collett et al (1986). They trained gerbils to find seeds located at a central point between two landmarks, and upon moving these landmarks further apart rather than searching at a point equidistant, which would suggest an egocentric view of the environment, they searched at the same distance from each of the landmarks. This would suggest that they had formed a map or reference framework of the environment that was based on cues from this environment. Wilkie & Palfrey (1987) and Zipser (1986) argued that this framework could still be animal-centred, in that it forms an egocentric matrix of the environment and then transforms this as it moves around in the environment, or as the environment itself changes.
Morris (1981) was able to show in that a hippocampal lesion affects a rat's ability to learn to return to a safe position in a milk maze, it became clear that a neurophysiological approach to the question may be useful.
O'Keefe (1991) suggested that "place cells" in the pyramidal CA1 and CA3 regions, which fire...
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