Brain Structure, Localisation of Function and Scanning Techniques

Why a psychologist studies the cortex

You have almost certainly met the brain before, in Biology. There it is an organ: it coordinates the body, it sits at the top of the nervous system, and it has parts with jobs. Psychology asks a different question about exactly the same tissue. Your specification calls the answer cognitive neuroscience: the study of how brain structure and function relate to behaviour and cognition - to what people do, and to how they think, remember and perceive. That is the thread running through this whole module, and it is what makes lobes and areas psychology rather than biology. The claim being investigated has a name: localisation of function. It says that a particular mental function does not float somewhere in the head in general, but is carried out by a particular place in the brain. Movement here; touch there; vision at the back. It is a strong claim, and the interesting part of this topic is not the list of places - it is what evidence could possibly support a claim like that. ⚠️ You will meet exactly two kinds of evidence, and the module is built around them. Damage, where injury or illness takes a region out of action and we see what stops working - evidence nobody chose to create. And scanning, where the living brain can be pictured while a person is doing something. Neither is perfect, and knowing why is worth a mark. Everything below assumes the previous module in this topic: the neuron, the synapse, and how a signal travels. This one starts where the signal arrives.

Words for the areas and the evidence

Your specification names five localised areas. Learn them as a function plus a place, because that pairing is what localisation means.

Tap the area that plans movement

This brain faces left, in the direction of the arrow. Six regions are shaded. Tap the area that controls voluntary movement. It is one of the two narrow strips running down from the top, and it is the one nearer the front.

Match each area to the job it does

A lobe is a place; an area is a job

Students lose marks here by treating "lobe" and "area" as the same word twice. They are two different levels of description, and a question can ask for either.

Which two statements about localisation hold

Select the TWO statements that are accurate.

• The motor and somatosensory areas lie next to each other, in the frontal and parietal lobes respectively
• Localisation means a particular function is carried out by a particular area rather than by the whole brain
• The visual area is in the frontal lobe, because vision is what we pay attention to first
• Localisation means each area works entirely on its own, with no connection to the others

Three ways of looking inside

Localisation is a claim about where a function lives, so it needs evidence. The second kind is scanning: producing an image of a living brain, in some cases while the person is actually doing something. Your specification names three techniques. CT. PET. fMRI. ⚠️ Now the useful part, and it is a piece of exam advice rather than a piece of content: your specification names these three and gives no comparative detail for any of them. It does not ask you to say which has better resolution, which costs more, or which uses radiation. So do not revise a comparison table, and be suspicious of one you find elsewhere - you would be learning material this specification does not assess. Know the three names, and know what scanning is for: it lets researchers relate activity in a particular region to a particular task, which is cognitive neuroscience doing its job. ⚠️ Two studies are named on this part of the specification in exactly the same way, and the same advice applies. Penfield's study of the interpretive cortex, which concerned a region of the cortex he called interpretive. And Tulving's 'gold' memory study, which sits here as an example of brain imaging used to investigate memory. Both are named only. You are expected to recognise the names and know roughly what each concerned - not to reproduce a procedure, a sample or a set of findings. ⚠️ If your notes contain detailed procedures for either, somebody has invented them. Recognising a name is a real revision task; it is simply a much smaller one than you might assume.

Localisation in words

Localisation of function is the idea that a particular mental function is carried out by a particular _____ of the brain. The _____ area controls voluntary movement and sits in the frontal lobe; the somatosensory area, immediately behind it, receives touch, temperature and pain. Information from the eyes is processed by the _____ area at the back of the brain, and information from the ears by the _____ area. The study of how brain structure and function relate to behaviour and cognition is called cognitive _____.

Damage as evidence, answered twice

A question asks: "Explain how damage to the brain can provide evidence for localisation of function." Four marks. A weak answer: "If someone damages their brain they might not be able to move properly, which shows the brain controls movement." That is true, and it earns very little, because it does not connect a particular region to a particular function - which is the whole of what localisation claims. A strong answer: "Neurological damage, from a stroke or a head injury, affects a particular region of the brain rather than all of it. If damage to one region is followed by the loss of one specific ability - for example, damage in the frontal lobe followed by weakness in voluntary movement on the opposite side of the body - then that ability can be linked to that region. The pattern is informative because it is selective: other abilities continue to work normally. Repeated across many patients, this supports the claim that the function is localised to that area rather than spread across the brain." ⚠️ Look at what did the work: the word *selective*. Evidence for localisation is not that damage causes problems; it is that specific damage causes specific problems while leaving other things intact. ⚠️ And the evaluation point, if a fifth mark is going: damage is not an experiment anyone designed. Injuries and strokes do not fall neatly inside one area, no two patients are damaged identically, and we cannot know exactly what a person could do beforehand. So the evidence is real but untidy, which is a large part of why scanning mattered so much when it arrived. Saying that is what separates a strong answer from a complete one.

The claim that outruns the evidence

Four statements about brain-damage evidence. Select the ONE that claims more than the evidence supports.

• Damage to one region followed by the loss of one specific ability, while others continue normally, links that ability to that region.
• Because damage to the frontal lobe can affect movement, the frontal lobe is the only part of the brain involved in moving.
• Injuries rarely fall neatly inside a single area, which makes the evidence harder to interpret.
• We usually cannot know exactly what a patient could do before the damage occurred.

From damage to conclusion

Put the steps of the reasoning in order, as a researcher would follow them.

• A patient has damage affecting one particular region of the brain
• One specific ability is lost, while other abilities continue to work normally
• The loss is linked to that region, because the effect was selective rather than general
• The same pattern is found in other patients with damage to the same region
• The function is concluded to be localised to that area rather than spread across the brain

What would you expect to see

A person has a stroke affecting a region at the back of the brain. Which effect would a psychologist expect, and why?

• Difficulty with vision, because the visual area is in the occipital lobe at the back of the brain
• Difficulty moving one side of the body, because movement is controlled at the back
• Difficulty hearing, because the ears are closest to the back of the head
• No effect on any specific ability, because functions are spread evenly across the brain

Deciding what the evidence shows

Work through how a cognitive neuroscientist would reason about a case.

• After a head injury, a patient can no longer produce fluent speech, but understands everything said to them and moves normally. What does the pattern suggest?
• The team wants stronger evidence without waiting for another injury. What can scanning add?
• A student writing this up wants to describe the scanners. What should they include?
• Finally, what is the most credit-worthy thing to say about localisation as a whole?

Explain localisation and its evidence

Explain what localisation of function means, name the localised areas and their functions, and explain how psychologists have gathered evidence for the claim.

• Define localisation of function in a sentence
• Name the four lobes and the cerebellum with their basic functions
• Name the localised areas the specification gives, each with its function and its lobe
• Explain how damage provides evidence, using the idea that the effect is selective
• Explain one limitation of evidence from brain damage
• Explain what scanning adds, and name the three techniques
• Finish by explaining that areas are specialised rather than isolated
• Say what cognitive neuroscience means, and why it is the reason psychologists study this at all