Source: image brain lobes: public domain; http://en.wikipedia.org/wiki/File:Lobes_of_the_brain_NL.svg
Hello class. So each side the brain, as you recall, is divided into four distinct lobes. And these are areas that control specific aspects of our brain and our mental processes. So the frontal lobe, the part at the very front of the brain, is associated with things like movement, sense of self, reasoning, planning, and language production. The other three lobes of the brain are associated with different kinds of sensory processing and processes of the information that's being taken from the rest of the body. And we're going to look at these in a bit more detail today.
So we'll be taking a look at the parietal lobe, the temporal lobe, and the occipital lobe. So first we have our parietal lobe, which is a lobe that's bordering directly next to the frontal lobe. And this is a lobe that's related directly to the somatic senses, which is to say touch, pressure, temperature, all the information that we're receiving from our skin. So you understand that's a very large area. So this is an important area of the brain as well.
Now, a very important area of the parietal lobe is the primary somatosensory cortex, which is this area that's right next to the frontal lobe, and it's actually right across from the primary motor cortex. And you'll see there's some similarities between those two areas of both lobes. The primary somatosensory cortex is the area that's directly related to taking in all of that somatic sensory information from our skin all throughout our bodies. Now, it's laid out as a sort of homunculus, which is to say that it starts off at the top here with our feet and then moves gradually up the body as we move down.
So we've got our legs, and then our torso, our arms, and our hands. And then down to our faces and things like that. Now, there are larger areas of the somatosensory cortex devoted to more sensitive or intricate areas of our bodies. So the area that's devoted to our feet is much smaller than the area devoted to our hands. Because they're a lot more important to us and a lot more intricate. And the things that we need to sense with them are more important. The same with our face. It's a very large area towards the bottom here.
Next, we have the temporal lobe. The temporal lobe here is the lobe that's located directly on the side of the brain. And this is related specifically to hearing and information that we receive from our ears. Now, the primary auditory area is this area that's right at the top located underneath the somatosensory cortex. And this is the area that does all the processing of our information that related to our hearing. It's also in this lobe an area that's related to understanding of language, which makes sense because we're talking about hearing. And how do we get language? Through hearing. Right?
So another important area that we talk about is Wernicke's area, which is the area that's located near the occipital lobe. And this is related to creating meaning and understanding out of language. This is named for the German neurologist named Carl Wernicke, who studied patients that had damage to this area of their brain. And he noticed a certain kind of aphasia, which is to say that when they would hear the language being spoken they would take it in, but they couldn't create any kind of understanding or meaning out of it. So if somebody told you something like say a chair, you might have heard those sounds that came in, ch air. But you couldn't understand what that word actually means.
Now, this is used in conjunction with Broca's area in the frontal lobe to create a sort of language pathway in the brain. So this goes from understanding in the temporal lobe and creating meaning, that passive language, all the way to active language production in the frontal lobe. And that's the Broca's area. So that's an important area to learn more about if you don't understand that already.
Finally, we have the occipital lobe, which is the lobe that's located right at the back of the brain here. And this is the area that's related directly to seeing and understanding visual information. It's connected to the eyes via the optic nerve. So there's a sort of visual pathway going from our eyes directly to this area of the brain. And the important area to remember is the primary visual area, which is the area that's located at the very back of the occipital lobe.
And this is the area that's related to processing all of that visual information. Now, people that have damage to this area of the brain, the primary visual area, can have all different sorts of agnosia, which is different from aphasia. So remember agnosia has to do a vision. Agnosia means that they're able to see an object, but they can't recognize it. So they take in the information, but they can't process it and make meaning out of it. For example, visual aphasia is a situation where there's damage to the left occipital lobe. And the people can describe what they see. They can create some kind of visual information, but they can't create meaning out of it.
So if they see a chair, they might be able to say there are these long, straight legs and this flat surface on the top, but they can't put those pieces together to say it's a chair. Similarly, people can also have facial agnosia or prosopagnosia, which is to say that they can't recognize people by sight. So they look at somebody, that can't say who they are even if their close family members or people they know very well.
However, if the person speaks, if there's some kind of auditory recognition, then they can automatically recognize them. Because that's not the area of the brain that's been damaged. So these are different kinds of ways that we can understand the function of all three of these different lobes of the brain.
Terms to Know
The part of the cerebral cortex related to somatic senses (touch, pressure, temperature).
Primary Somatosensory Cortex
Area next to frontal lobe across from primary motor cortex related to senses across the body.
The part of the cerebral cortex located on side of brain, related to the processing of hearing.
Primary Auditory Area
The area at top of the temporal lobe near primary motor/somatosensory cortices related to hearing and language understanding.
The area near occipital lobe related to creating meaning and understanding language.
The part of the cerebral cortex related to the processing of visual information and seeing.
Agnosia (visual and facial)
When a person has damage to the left occipital lobe and can describe what they see but not say what it is, or cannot create meaning out of the visual information.