All parts of the brain › Reading

What part of the brain is used for reading?

Mainly a network on the left side of the brain that joins seeing to language. The visual cortex in the occipital lobe takes in the letters; the visual word form area on the left fusiform gyrus recognises them as letters and words; then the angular and supramarginal gyri of the parietal lobe, the back of the superior temporal gyrus (Wernicke’s area) and the inferior frontal gyrus (Broca’s area) link the written word to its sounds and its meaning. Writing is only about 5,500 years old, so the brain did not evolve to read: reading reuses object-naming circuits in the left hemisphere. [1][2][3]

Wernicke’s area and Broca’s area are regions on these gyri, not separate shapes. The 3D model draws only whole gyri, so the gyrus that holds each area is lit; the area’s exact border is not drawn.

The visual word form area is a region on the fusiform gyrus, not a separate shape. The 3D model has no shape for it, so the whole fusiform gyrus is lit; the region’s exact border is not drawn.

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

Slice

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; .

Reading: 6 parts lit

Occipital lobe, fusiform gyrus, angular gyrus, supramarginal gyrus, superior temporal gyrus and inferior frontal gyrus. Tap one to see where it is and what it does.

The parts and their roles

Holds the primary visual cortex, which first receives the image of the letters from the eyes and passes it forward along the ventral “what” stream toward the fusiform gyrus. [4][5] Where is the occipital lobe?
On the left side it holds the visual word form area: portions of the left fusiform gyrus are believed to be used in word recognition, starting about 100–250 ms after a word is seen. [6][2] Where is the fusiform gyrus?
Brodmann area 39 at the back of the parietal lobe; it passes what is seen on to Wernicke’s area to make meaning out of written words, and Norman Geschwind proposed it turns the written word into inner speech. [7] Where is the angular gyrus?
Brodmann area 40, just in front of the angular gyrus; it works with the angular gyrus to link words with meanings, and both sides are active when people make choices about the sounds of words. [8][3] Where is the supramarginal gyrus?
Its back part on the left is used for phonological processing, the sounds of words, and holds Wernicke’s area, linked to understanding words. [3][9] Where is the superior temporal gyrus?
Holds Broca’s area: the pars opercularis (area 44) takes part in the sounds of language and speech production, the pars triangularis (area 45) in the meaning of words. [10] Where is the inferior frontal gyrus?

Named areas on the lit gyri

Wernicke’s area, on the : At the back of the superior temporal gyrus; the angular gyrus passes visually perceived words to it so they can be given meaning. [11][7]
Broca’s area, on the : The pars opercularis (Brodmann area 44) and pars triangularis (area 45) of the inferior frontal gyrus; the first takes part in the sounds of language, the second in meaning. [10][12]
The visual word form area, on the : A functional region of the left fusiform gyrus and the cortex around it, thought to identify letters and words from their shapes before they are linked to sound or meaning; its right-side counterpart is part of the fusiform face area. [2]

How they work together

The eyes do not glide along a line: they stop in fixations of 200–250 ms on average (from 100 ms to over 500 ms), jump about 7–9 characters at a time, and a skilled reader goes back over the text about 15% of the time. [13]
In the visual word form area, early activity about 100–250 ms after a word appears fits recognising its letter pattern, and later activity at about 300–500 ms fits matching it to a known word. [2]
There are two routes from print to sound: a sight route that looks a known word up whole, which is the only way to read exception words such as “pint” or “colonel”, and a sound-it-out route that applies letter-to-sound rules, which is the only way to read a made-up word. [14]
Sounding text out is tied to the back of the superior temporal gyrus and the inferior parietal lobule (where the supramarginal and angular gyri lie), and the meaning of text to the inferior and middle temporal gyri; the left fusiform gyrus and supramarginal gyrus also work when people spell. [3]
Because the alphabet is so recent, the visual word form area probably did not arise for words; one idea is that it is tuned to shapes found in nature that letters happen to use. Most adults read English at 175–320 words per minute, and claims of 1,000 are judged impossible. [2][1]
Honest limit: the visual word form area, Wernicke’s area and Broca’s area are functional regions, not shapes of their own on this model, so the whole fusiform, superior temporal and inferior frontal gyri light and the whole occipital lobe stands for the visual cortex; whether the visual word form area is one distinct area is still debated, its place differs a lot from person to person, and the model shows both sides even though reading leans to the left. [2][11][12]

Sources

Facts describe anatomy and normal function only. A part lit here takes part in reading; 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.