According to a news release from the American Association for the Advancement of Science, a “sixth sense” really exists. No, it’s not the ability to see dead people, but rather it’s what allows people to count.
New research reveals that humans utilize a part of the brain that is organized topographically to determine, for example, the number of jelly beans in a bowl or the number of cookies in a jar. This means that the neurons that labor to make this “numerosity” estimation are organized in a shape that allows those neurons most closely related to communicate and interface over the shortest possible distance.
The other senses — sight, hearing, touch, smell and test — also have this feature.
Until recently, however, scientists weren’t able to locate it, which had led to some skepticism as to whether a map for numerosity exists.
Benjamin Harvey of Utrecht University and his colleagues have discovered signals that show that the much-debated numerosity map really does exist.
Numerosity is different from symbolic numbers.
“We use symbolic numbers to represent numerosity and other aspects of magnitude, but the symbol itself is only a representation,” Harvey noted.
Numerosity selectivity in the brain comes from visual processing of image characteristics, where symbolic number selectivity comes from the recognition of the shapes of numerals, written words, and linguistic sounds that represent numbers.
“This latter task relies on very different parts of the brain that specialize in written and spoken language,” Harvey added.
To discover the map, Harvey and his colleagues asked eight study participants to examine patterns of dots that differed in number over time, all the while studying the neural response properties in a numerosity-associated part of their brain utilizing high-field fMRI. This technique allowed the researchers to scan the subjects for far less time per session than would have been necessary with a less powerful scanning technology.
Harvey and his team turned to population receptive field modelling to measure neural response.
“This was the key to our success,” Harvey posited.
It allowed the scientists to model the human fMRI response properties they saw following results of recordings from macaque neurons, in which numerosity experiments had been conducted more fully.
They discovered a topographical layout of numerosity in the human brain: the small amounts of dots the participants saw were encoded by neurons in one area of the brain, the bigger amounts, in another.
The discovery shows that topography can also develop for higher-level cognitive functions.
“We are very excited that association cortex can produce emergent topographic structures,” Harvey said.
The finding may assist scientists with their quest to better study the neural computation underlying number processing
By (National Monitor)