Do cortical maps adapt to optimize information density?

Topographic maps are found in many biological and artificial neural systems . In biological systems, some parts of these can form a significantly expan ded representation of their sensory input, such as the representation of th e fovea in the visual cortex. We propose that a cortical feature map should be organized to optimize the efficiency of information transmission throug h it. This leads to a principle of uniform cortical information density acr oss the map as the desired optimum. An expanded representation in the corte x for a particular sensory area (i.e. a high magnification factor) means th at a greater information density is concentrated in that sensory area, lead ing to finer discrimination thresholds. Improvement may ultimately be limit ed by the construction of the sensors themselves. This approach gives a goo d fit to threshold versus cortical area data of Recanzone et al on owl monk eys trained on a tactile frequency-discrimination task.