  As subjects perceive the sensory world, different stimuli elicit a number of
neural representations. Here, a subjective distance between stimuli is defined,
measuring the degree of similarity between the underlying representations. As
an example, the subjective distance between different locations in space is
calculated from the activity of rodent hippocampal place cells, and lateral
septal cells. Such a distance is compared to the real distance, between
locations. As the number of sampled neurons increases, the subjective distance
shows a tendency to resemble the metrics of real space.
