This lesson will identify, classify and discuss the functions of the parietal lobes and primary somatosensory area. The temporal Lobes, primary auditory area, and Wernicke's area will be defined, delineated and discussed.
Welcome to today's lesson on the cerebral cortex. Each side the brain, as you recall, is divided into four distinct lobes. These areas control specific aspects of the brain and mental processes. This tutorial will focus specifically on:
The parietal lobe is a lobe that's bordering directly next to the frontal lobe. 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, and therefore this is an important area of the brain as well.
A very noteworthy area of the parietal lobe is the primary somatosensory cortex, which is the 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.
In addition, 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 ultimately the things that we need to sense with them are more important.
The temporal lobe is located directly on the side of the brain. It is related specifically to hearing and information that we receive from our ears.
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 is related to our hearing.
It's also in this lobe that there is an area that's related to the understanding of language, which makes sense because this concerns hearing. And how do we get language? Through hearing.
Wernicke's Area is located near the occipital lobe and this is related to creating meaning and understanding out of language.
This is named for the German neurologist, Carl Wernicke, who studied patients that had damage to this area of their brain. Wernicke 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 the word "chair," you might have heard those sounds that came in (e.g., "ch air"), but you couldn't understand what that word actually means.
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 Broca's area.
The occipital lobe is located right at the back of the brain and is related to seeing and understanding visual information. It's connected to the eyes via the optic nerve, and so there's a sort of visual pathway going from our eyes directly to this area of the brain.
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. This area is related to processing all of that visual information. People with damage to this area of the brain, the primary visual area, can have all different sorts of agnosia, which is a different form of aphasia; agnosia has to do a vision in particular.
Agnosia means that a person is 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.
Visual agnosia is a situation where there's damage to the left occipital lobe. Samantha has damage to her left occipital lobe. She can describe what she sees and can create some kind of visual information, but she cannot create meaning out of it.
When Samantha sees a chair, she describes long, straight legs and a flat surface on the top, but she is unable to put those pieces together to say it's a chair.
People can also have facial agnosia or prosopagnosia, which means they cannot recognize people by sight. They are unable to identify a person even if it is a close family member. However, if there's some kind of auditory recognition when the person speaks, they can automatically recognize them. Why is that? Because the area of the brain involving auditory recognition has not been damaged.
This tutorial discussed the parietal lobe, which is responsible for touch and pressure. The temporal lobe is associated with hearing, and Wernicke's Area handles language. Finally, the occipital lobe processes visual information.
Source: This work is adapted from Sophia author Erick Taggart.
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.
The part of the cerebral cortex related to the processing of visual information and seeing.
The area at top of the temporal lobe near primary motor/somatosensory cortices related to hearing and language understanding.
The part of the cerebral cortex located on side of brain, related to the processing of hearing.
The area near occipital lobe related to creating meaning and understanding language.