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Where vs. What: The Parietal Lobe and the Temporal Lobe Are Not Interchangeable Real Estate · Understanding the Brain

• 0:01
  Speaker 1: We're going to be looking at the difference between parietal
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  Speaker 1: lobes and temporal lobes. The brain is not a set
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  Speaker 1: of personality rooms. It is a set of processing territories
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  Speaker 1: that fail in characteristic ways when they're damaged. Two of
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  Speaker 1: the most commonly mixed up territories sit right next to
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  Speaker 1: each other along the sylveon fissure, the parietal lobe and
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  Speaker 1: the temporal lobe. They share blood supply, white matter, and
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  Speaker 1: a long history of being flattened into the thinking part
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  Speaker 1: in the back. However, they do different jobs. Let's start
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  Speaker 1: with the location. The parietal lobe sits behind the central
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  Speaker 1: sulcus and above the temporal lobe. Its anterior strip, the
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  Speaker 1: postcentral gyrus, is primary somatosensory cortex. Touch, pain, temperature, and
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  Speaker 1: proprioception arrive here in a body map. Behind that map,
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  Speaker 1: association cortex builds a model of where the body is
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  Speaker 1: in space and where objects relative to the body exist.
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  Speaker 1: That is why parietal damage produces problems that look spatial
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  Speaker 1: even when vision is intact. A patient may feel a
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  Speaker 1: limb and still not use it. They may eat only
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  Speaker 1: from the right side of the plate. They may be
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  Speaker 1: unable to reach accurately, address the left arm, or copy
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  Speaker 1: a simple drawing. Classic left hemisphere parietal injury can also
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  Speaker 1: disrupt calculation, writing, finger naming. left-right orientation, what they call
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  Speaker 1: a Gerstmann's cluster, because those skills lean on spatial and
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  Speaker 1: symbolic map, not on intelligence. The temporal lobe hangs below
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  Speaker 1: the Sylvian fissure, like a thumb off the side of
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  Speaker 1: the hemisphere. Its superior surface is auditory cortex. Speaks sounds
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  Speaker 1: are decoded here before they become language. In the language-dominant hemisphere,
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  Speaker 1: the posterior superior temporal region is the neighborhood of Wernicke's area.
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  Speaker 1: A fluent speech that no longer carries meaning or comprehension
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  Speaker 1: that collapses while articulation stays smooth. Move medially and you're
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  Speaker 1: in memory country, hippocampus and surrounding cortex. Move ventrally towards
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  Speaker 1: the back and you're in, or the top, you're in
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  Speaker 1: with the stream. The what stream? Object recognition, face recognition,
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  Speaker 1: semantic knowledge. The amygdala sits at the anterior pineal tip
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  Speaker 1: and tags experience with threat and salience. Temporal damage therefore
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  Speaker 1: looks like lost names, lost tunes, lost episodes, lost faces,
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  Speaker 1: or a world that is heard but not understood. It
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  Speaker 1: does not usually look like neglect of half a space.
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  Speaker 1: So a clean contrast is the two visual streams. After
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  Speaker 1: early visual cortex, the dorsal stream runs up into parietal
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  Speaker 1: cortex and answers where and how. Location, motion, grasping. The
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  Speaker 1: ventral stream runs down into the temporal cortex and answers
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  Speaker 1: the what. Identity, category, and meaning. You can lose the
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  Speaker 1: ability to recognize a cup and still reach for it.
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  Speaker 1: You can recognize the cup and miss it with your hand.
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  Speaker 1: Those are not the same lesions. The lobes talk constantly.
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  Speaker 1: Language is not in Wernicke's area any more than space
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  Speaker 1: is in one gyrus. Reading pulls occipital form, temporal meaning,
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  Speaker 1: and parietal spatial attention into one act. A seizure that
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  Speaker 1: starts at the temporal lobe can smell burning toast and
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  Speaker 1: then empty memory. A stroke in the right parietal lobe
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  Speaker 1: can leave a person who insists nothing is wrong while
• 3:37
  Speaker 1: half the world has gone missing. That is anosogosnia, not stubbornness.
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  Speaker 1: If you write or teach about the brain, keep the
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  Speaker 1: verbs attached to the lobes. Parietal, locate, attend, reach, feel
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  Speaker 1: the body as a map. Temporals, hearing, name, remember, recognize,
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  Speaker 1: assign meaning. That's it for now.