How is Number Represented in the Brain?

Notes by Howard Gardner

A principal component of the theory of multiple intelligences has been the belief that the human nervous system has evolved to facilitate a number of relatively independent computations. Rather than a single intelligence, on which one draws for the full panoply of skills, there are neural regions or networks that are more specifically dedicated to language, number, music, and the like.

A quite original aspect of the theory is that the intelligences are not yoked to a specific sensory capacity: for example, linguistic intelligence (known to be represented in the left hemisphere of right handed individuals) is mobilized whether linguistic information enters through the ear, the eye, or (in the case of the blind reading Braille) the fingertips.

When MI theory was developed over 30 years ago, most of our knowledge of the brain basis of cognition came from the study of individuals who had suffered brain damage. The findings were consistent, but at a very gross level; brain damage does not follow strict guidelines! In the intervening era, researchers have developed far more sophisticated means of studying the representation of capacities in the brain.

study released in Science provides a number of fascinating findings. First of all, by using functional magnetic resonance imaging, it is possible to examine numerical capacities quite specifically in the human parietal cortex. Specific cortical areas, known as association cortex, are stimulated by numerical operations that occur across different sensory capacities; unlike, say, face recognition or tone discrimination, they are not restricted to a specific sensory cortex. Most remarkably, the size and manner of cortical representations actually reflects the size (technically, the numerosity) of the array; if you look at the pattern of neuronal arousal, you can tell whether the array contains few or many stimuli.

What I like best about the study is the clear implication that the human brain has evolved, not only to represent specific sensory input, but also to capture important distinctions that cut across the senses. I suspect that when scientists begin to study other intelligences, ranging from spatial to interpersonal, they will discover a clear rationale for the way these capacities are represented in the human brain.

To read the article in its entirety, click here.

Harvey, B.M. et al. “Topographic Representation of Numerosity in the Human Parietal Cortex.” (September 2013). Science, 341 (6150), pp. 1123-1126.