Hello, I hope that you had a great weekend.
So in today's episode, we're going to be talking about one of my absolute favourite topics. I know I say this a lot, but I just love psychology in all of its forms. Actually, in most of its forms, there are some areas of psychology I just hate.
However, this is one of my favourites. It was the first psychology topic I actually learned when I started IB psychology and I hope that you're all going to love it as much as I do.
So today's episode will be on localization and its the idea that certain areas of the brain are responsible for certain behavourial functions. For example, the frontal lobe is associated with higher-order thinking, judgment, and all of those quite intelligent functions.
Whereas, the optical lobe, which is at the back of the brain, is associated with sight.
I say associated with because we can't say definitively that one lobe of the brain is responsible for only that behaviour or only that certain behaviour. Because as you'll see in the later study that I'm going to tell you about, it's actually quite difficult to say that one area is responsible for it because you have this other thing called equipotentiality, which is the ability for one area of the brain to take over the function of another. So that's why we say associated because there's a strong link between the area of the brain and that function. But to essentially protect ourselves, we can't say that it's 100% certain.
Now, localization can be split up into two areas. Strict localization, which is the idea that that certain behaviour is localised to that area of the brain only. Whereas weak localisation means that the behaviour isn’t strictly localised to one area so if one area of the brain fails another area can take over the function of that behaviour.
I just find it really interesting, especially some other studies do definitely make you a lot more interesting.
Broca (1865)
Broca was a French physician who treated a man for gangrene fever called: Lebrogne. By the age of 30, Lebrogne had lost the ability to speak and communicate.
However, all of his other functions were still in tac as when you tried to talk to him, he understood and tried to communicate back. Nevertheless, he could only say the word ‘Tan’ which he usually repeated twice.
His condition was named: Broca’s aphasias- the loss of articulated speech.
When ‘Tan’ died aged 50 a brain autopsy discovered a lesion in his frontal left hemisphere of the brain.
If you wanted to be specific… it was in the posterior inferior frontal gyrus area. Now that’s a mouthful!
After this discover Broca named the area of the brain after himself and concluded after studying another 25 patients that the Broca area was responsible for the forming of articulated speech.
Overall, this study supports the idea of strict localisation because it shows that if the Broca area is damaged that the function of speech is impaired as well.
Critical thinking:
One aspect of the study that makes it good is that Broca studied another 25 people before drawing his conclusion. Meaning that he had a large sample size so his conclusion could be supported.
However, Broca preserved Tan’s brain and 100 years later it was dissected, and the researchers found that the lesion wasn’t as neat nor confined to the Broca area as previously thought.
So, it is possible that the Broca area isn’t responsible for speech?
It is possible that another area of the brain that was affected by this lesion was, in fact, responsible for the forming of speech.
Lashley (1929)
On the other hand, not all functions of the brain are localised. One example that we’ll look at now is memory.
In a typical experiment, he would train a rat to go through a maze to find a food pellet without an error.
Following this, he would remove a part of the brain. These removed sections would range from 10% to 50%.
The point of removing certain areas of the brain was that if memory was stored in one place then if you removed certain areas of the brain one at a time you would eventually find it.
The results of his experiment didn’t support his theory that memory was localised. Therefore, he decided that it was because the amount of brain matter destroyed impacted memory and not the location. (known as the principle of mass action) and because one area of the brain could take over the function of another area of the brain. This is known of equipotentiality.
Therefore, as Lashley couldn’t find an area of the brain responsible for memory. This doesn’t support the theory of localisation, and he proposed that memory is evenly spread out through the brain.
His theory is generally accepted today but memory is known not to be as uniformly and evenly spread out as Lashley thought.
Critically thinking:
While Lashley did manage to prove that memory is not localised to one area of the brain. It begs the question and opens up the classic psychological debate of how far can we compare animals to humans as while we share a lot of our DNA with rats. As a result of physical differences and differences in our brain. Can this conclusion be accurately applied to humans?
Conclusion:
Personally, I think that we can agree that certain areas of the brain are localised to specific areas. While others are not.
What do you think?
Overall, localisation can affect behaviour because it demonstrates that certain areas of the brain are responsible for key behaviours that are important to humans. For example, the Broca area is responsible for articulated speech which is important for the survival of the species. The ability to communicate is one another.
I hope that you enjoyed today’s episode.
Please sign up for my mailing list and receive a FREE book.
Have a great week.
Kind regards Connor.