from within the medial entorhinal cortex have also been implicated in the process of path integration, actually playing the role of the path integrator while place cells display the output of the information gained through path integration. The results of path integration are then later used by the hippocampus to generate the cognitive map. The cognitive map likely exists on a circuit involving much more than just the hippocampus, even if it is primarily based there. Other than the medial entorhinal cortex, the presubiculum and parietal cortex have also been implicated in the generation of cognitive maps. Parallel map theory There has been some evidence for the idea that the cognitive map is represented in the hippocampus by two separate maps. The first is the bearing map, which represents the environment through self-movement cues and gradient cues. The use of these vector-based cues creates a rough, 2D map of the environment. The second map would be the sketch map that works off of positional cues. The second map integrates specific objects, or landmarks, and their relative locations to create a 2D map of the environment. The cognitive map is thus obtained by the integration of these two separate maps. This leads to an understanding that it is not just one map but three that help us create this mental process. It should be clear that parallel map theory is still growing. The sketch map has foundation in previous neurobiological processes and explanations while the bearing map has very little research to support its evidence. Cognitive maps in animals According to O’Keefe and Nadel (1978), not only humans require spatial abilities. Non-humans animals need them as well to find food, shelters, and others animals whether it is mates or predators. To do so, some animals establish relationships between landmarks, allowing them to make spatial inferences and detect positions. The first experiments on rats in a maze, conducted by Tolman, Ritchie, and Kalish (1946), showed that rats can form mental maps of spatial locations with a good comprehension of them. But these experiments, led again later by other researchers (for example by Eichenbaum, Stewart, & Morris, 1990 and by Singer et al. 2006) have not concluded with such clear results. Some authors tried to bring to light the way rats can take shortcuts. The results have demonstrated that in most cases, rats fail to use a shortcut when reaching for food unless