All parts of the brain › Functions › Numbers and maths

What part of the brain handles numbers and maths?

Numbers (maths, or math in American English) lean on the parietal lobe: the intraparietal sulcus, the groove between the superior parietal lobule and the angular and supramarginal gyri, is active whenever you think about a quantity, whether as a spoken word, an Arabic digit or a set of objects you are counting. [1][2]

The 3D brain needs JavaScript. The list of parts still says what each one does for numbers and maths.

Lit: whole parts; region borders not drawn.

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All 6 parts are lit together. Drag to turn, pinch or scroll to zoom, tap a part on the brain or a name in the list to focus it; .

The left angular gyrus retrieves arithmetic facts learned by heart, the prefrontal cortex takes the number on for further work, and the inferior temporal cortex reads the shapes of digits. [1][2]

The intraparietal sulcus is a region on the superior parietal lobule, not a separate shape. The 3D model has no shape for it, so the whole superior parietal lobule is lit; the region’s exact border is not drawn.

Numbers and maths: 6 parts lit

Superior parietal lobule, angular gyrus, supramarginal gyrus, prefrontal cortex, fusiform gyrus and inferior temporal gyrus. Tap one to see where it is and what it does.

The parts and their roles

Its lower edge is the horizontal part of the intraparietal sulcus (below), which separates it from the inferior parietal lobule. Subtraction, taught through handling quantities and strategies, relies more on the right intraparietal sulcus and the posterior parietal lobule, and parietal cortex shows shared activity for numbers and for space. [3][1] Where is the superior parietal lobule?
On the left, together with the left inferior frontal gyrus, it is active in exact calculation, retrieving arithmetic facts stored in words (such as times tables); the more active it is, the more competent a person’s arithmetic tends to be. Approximate calculation leans on other parietal areas of both hemispheres instead. [4] Where is the angular gyrus?
With the angular gyrus behind it, it makes up the inferior parietal lobule, which lies below the intraparietal sulcus, is active in calculation tasks and is thought to hold facts learned by rote, such as multiplication. [5][1] Where is the supramarginal gyrus?
Holds neurons tuned to a preferred number of items, found first in monkeys and then in human imaging. Number-tuned neurons in the intraparietal sulcus respond sooner and frontal ones later, which suggests a number is processed first in the parietal lobe and passed forward when it has to be worked with; frontal activity in calculation overlaps areas for working memory and attention. [1] Where is the prefrontal cortex?
Part of the human inferior temporal cortex (with the inferior and middle temporal gyri), which is implicated in processing the shapes and symbols of numbers needed to calculate with Arabic digits. The source names that cortex, not the fusiform gyrus alone. [1][6] Where is the fusiform gyrus?
One of the higher levels of the ventral visual stream, which represents objects, places, faces and colours; it may also be involved in recognising numbers. [6] Where is the inferior temporal gyrus?

Named areas on the lit gyri

The intraparietal sulcus, on the : A groove, not a shape: its horizontal part separates the superior parietal lobule above from the inferior parietal lobule (the supramarginal and angular gyri) below, so the gyri on both banks are lit. It is active whenever we think about a number, spoken or written, as a word or as an Arabic digit, or judge how many objects a set holds; the right side does more in non-symbolic estimation, the left more with symbols and operations. [7][3][2]

How they work together

Stanislas Dehaene and colleagues propose that the two parietal regions play complementary roles: the intraparietal sulcus for estimating, comparing and on-line calculation (often tested with subtraction), the inferior parietal lobule for facts learned by rote, such as multiplication. Multiplication also uses a left-sided network of the inferior frontal cortex and the superior and middle temporal gyri. [1]
In monkeys trained to hold a number of dots in mind for a few seconds, neurons in the intraparietal sulcus and frontal cortex had a preferred number: one firing most for four fired less for three or five and less again for two or six. The tuning follows Weber’s law, as in human fMRI with sets of 16 and 32 dots: telling two sets apart is easier at a ratio of 2 than at 1.25. [1]
Numbers and space are tied: people answer faster to larger numbers on the right side of space and to smaller numbers on the left (the SNARC effect), though the effect varies with culture and context. [1]
Infant brain recordings with near-infrared light show the parietal lobe responding to number before language develops; number may start in the right hemisphere and become bilateral with experience of symbols and counting. [2]
Honest limit: these are networks seen in brain imaging and in recordings from monkeys, not single centres. The digit-reading line is the least settled: the source ties the shapes of numbers to the inferior temporal cortex as a whole, so both gyri are lit rather than a guessed spot. [1][6]

A sum with several steps also needs working memory to hold the numbers carried along; frontal activity in calculation overlaps the working memory network, which lights the superior parietal lobule and supramarginal gyrus as well. [1] What part of the brain controls working memory?

Sources

Facts describe anatomy and normal function only. A part lit here takes part in numbers and maths; it does not do it alone, and it does other jobs too. The 3D model is the adult male BodyParts3D brain (credits and licence); on it the brainstem includes the midbrain, pons and medulla, so lighting the brainstem lights all three.