The Parietal Lobe

Touch, body sense, space and number: the parietal lobe builds your sense of where your body is and where things are around you — and its damage can make half the world disappear.

The parietal lobe lies behind the central sulcus and above the temporal lobe. It is the brain's hub for the body and space.

Touch and body sense

Just behind the central sulcus is the primary somatosensory cortex, which receives touch, pressure, vibration, temperature, pain and proprioception (the sense of where your limbs are) from the opposite side of the body, arranged as a body map — the sensory homunculus, with large areas for the lips, tongue and fingertips.

Space and action

Further back, the posterior parietal cortex combines touch, vision, hearing and body position into a sense of where things are relative to you. It guides reaching and grasping, eye movements and attention. This is part of the visual "where/how" pathway (the dorsal stream) running from the occipital lobe.

Numbers, reading and more

Regions around the intraparietal sulcus are active when people estimate quantities and do arithmetic; damage can cause acalculia. The angular gyrus and supramarginal gyrus on the left are involved in reading, writing and language. Gerstmann syndrome, from damage to the left angular gyrus area, combines trouble with writing, arithmetic, telling left from right and naming fingers.

Hemispatial neglect

Damage to the right parietal lobe, often from a stroke, can cause hemispatial neglect: the person ignores the left side of space. They may eat only the food on the right half of the plate, shave only the right side of their face, or, when asked to draw a clock, cram all the numbers onto the right side — not because they can't see the left, but because their brain doesn't attend to it.