The study of the brain is called neuropsychology and it's a huge topic. Most textbooks will go into much more detail than I will and there are hundreds of helpful websites on brain science. I'm focussing on the core psychology students will need to know for the exam and to make sense of other studies and theories in the Edexcel course.
|
WHY STUDY BRAINS?The brain is the seat of consciousness. The brain is where our decisions originate and where processes that lead to our feelings and memories take place. It is where your "self" is located.
The mind is something different. If the brain is a physical organ, the mind is something non-physical: it is the collection of all your thoughts, wishes, memories, feelings and intentions. Psychology is the study of the mind (the Greek word psyche means "mind") but neuropsychologists are interested in the brain because it seems to shape the mind. We know that changes to the brain produces changes in mental states. We can see this when people take drugs or suffer brain damage, such as from a stroke. Some psychologists argue that the brain is the mind: that all mental states are in fact brain states and once we fully understand the brain we will fully understand the mind, with nothing left over. This is a determinist view, because it claims that the biology of the brain determines all our thoughts. Other psychologists disagree, saying that it is reductionist to reduce all mental states to brain states. Currently, there seems to be more to the mind than just the brain. For example, the same processes in the brain seem to produce different thoughts or feelings in different people. However, our investigation into the brain is incomplete and we are discovering more about the brain all the time.
Brain research used to be limited to examining the dead brains of corpses. This was even less helpful than it sounds, because dead brains liquefy within hours. However, the invention of brain imaging technology has revolutionised our understanding of the brain, because now we can study living brains and "catch them in the act" of thinking or remembering.
THE CENTRAL NERVOUS SYSTEM (CNS)
The brain is important, but it doesn't stand all by itself. It works as part of the Central Nervous System (CNS) which includes the nerves running down the spine. The brain and spinal cord together make up the CNS.
Creatures with a CNS are known as vertebrates - a category which includes humans and all other mammals, reptiles, birds and fish, but not (for example) insects or octopodes.
As well as the CNS, you have other nerves in your body. This is the Peripheral Nervous System, which stretches out from your brain and spinal cord into every other part of your body. The Peripheral Nervous System includes sensory nerves (which carry information back to the brain as sensations - the "five senses") and motor nerves (which carry messages from the brain, telling muscles to move and glands to release their hormones). THE TWO HEMISPHERESThe brain is made up of two similar-looking halves called hemispheres. The two hemispheres are linked by a "bridge" of nerve fibres called the corpus callosum. The corpus callosum allows the left and right hemispheres to communicate with each other.
Yes, the corpus callosum features in the Classic Biological Study by Raine et al. because the murderers in that study showed less activity in the corpus collosum, which suggests their hemispheres weren't communicating properly.
The two hemispheres look identical but the brain is not really symmetrical. This is because the left and right hemispheres specialise in different things. The way different sides of the brain have different functions is called brain lateralisation.
An obvious example of brain lateralisation is that each hemisphere controls a different side of the body. However, it's not as you think: the left hemisphere controls most of the right side of the body, while the right hemisphere controls most of the left side. So if you raise your left hand, that's your right hemisphere controlling the hand. The two hemispheres have other differences too that are revealed when people suffer brain damage to one side of the brain only (such as a stroke). The brain's language centre is in the left hemisphere and damage to this takes away the power to speak or write (but not to understand language - the right hemisphere can do that). The left hemisphere seems to specialise in reasoning and numbers and more abstract thought; spatial awareness (like reading maps or judging distances) is based in the right hemisphere as is musical ability and artistic creativity. 
Left handed people use their right hemisphere to control their writing hand. Over the years, their right hemisphere may pick up some language ability. It's not unusual for left-handers to retain more language ability than right-handers after a stroke that has damaged the left hemisphere.
There's a popular idea that one hemisphere is usually more dominant than the other. This may influence the abilities you are good at and possibly your personality too.
The right-brain looks more fun, in a zany, hippie kind of way. This strikes me as "pop psychology" rather than true science, but if you're interested in identifying your own dominant hemisphere, the test below is a good one:
You don't need to know more than this for the course, but there has been a lot of research into brain lateralisation and the findings are very surprising. For example, in the 1950s Roger Sperry experimented on patients who had undergone brain surgery that cured their epilepsy by separating the two hemispheres of their brains. They were left with two brains instead of one. The results were astonishing.
THE CEREBRAL CORTEXHuman brains have a complex outer layer called the cortex. The cortex handles a lot "higher" brain functions, such as conscious thought and interacting with the world around us. It is divided into a number of areas with different functions, the most important being the four lobes.
In fact there are 8 lobes, because each hemisphere has all four lobes - so there's a left- and a right- version of each of the lobes. As long as your corpus callosum is working properly, the lobe should communicate with its "partner" in the other hemisphere
The frontal lobe handles most of our conscious planning, especially an important part of it called the pre-frontal cortex. Because it is important for self-control and decision-making, it has a big role to play in handling aggression, which is why it was studied by Raine et al. (1997) in the Classic Biological Study. Raine observed murderers showed less activity in the frontal lobe compared to a non-criminal control group.
The temporal lobe handles most of our memory functions, which is why it was studied by Schmolck et al. (2002) in the Contemporary Cognitive Study: Schmolck looked at patients who had enormous memory problems because of brain damage to the temporal lobe. The occipital lobe is at the back of the brain, but it processes sight and our sense of our environment. The parietal lobe controls language but also specialises in touch and directing bodily movements. THE LIMBIC SYSTEM
Beneath the cortex is a set of brain structures called the sub-cortical (beneath the cortex) structures. One of the most important of these is the thalamus, which sits at the centre of a group of structures called the limbic system. The limbic system handles memory but also raw appetites and desires - sleep, hunger, aggression and sex. It is thought to be the source of all our basic emotions.
The cerebral cortex is fully developed only in humans. On the other hand, the limbic system is the part of the brain we share with most other animals. The thalamus is sometimes called "the brain's switchboard", since it handles all the messages coming in from the brain and routes them to where they need to go. 
You'll notice the olfactory bulb is located nearby. This brain structure processes smell. Its link to the limbic system explains how smells can trigger hunger (bacon frying) or sexual arousal (perfume) but also fear (as when animals pick up a threatening scent).
This video covers lots of areas of the brain you don't need to know about, but it's quick and concise and very clear.
|
|
THE IMPORTANCE OF NEUROTRANSMITTERS
|
|
THE IMPORTANCE OF HORMONES
|
|
APPLYING NEUROPSYCHOLOGY TO REAL LIFE
|
|
Testosterone is linked to "dominance" among animals. It tends to peak in the mating season, when male animals (such as red deer) fight for dominance.
Testosterone has also been shown to peak when human males are single, decline when they get married, and peak again after divorce or separation (Mazur & Booth, 1998). |
|
Some disturbing animal experiments into aggression and the case study of Mark Laribus, whose uncontrollable aggression was linked to a brain tumour near his amygdala
DRUG USE & ABUSE
Recreational drugs (which are taken for pleasure rather than for medical reasons) have an affect on the CNS, which is why they are sometimes called 'psychoactive' drugs. Most of these drugs are illegal, with the exception of so-called "legal highs" that are not yet illegal.
Alcohol is a legal drug that has many effects. It blocks serotinin receptors. Since serotonin calms the brain and inhibits mood, blocking serotonin receptors lifts our mood and makes us uninhibited.
Alcohol is also linked to aggression. Stephanie Gorka et al. (2013) used MRI scans to study activity between the prefrontal cortex (which handles decision making) and the amygdala (which handles emotions). The participants who had taken alcohol showed less brain activity than a control group. This suggests alcohol interferes with the brain's ability to pass information between the emotion centre (the amygdala) and the decision-making centre (the prefrontal cortex).
Nicotine is another legal drug and seems to affect dopamine receptors in a part of the brain called a "reward pathway". The nicotine binds to the receptors the way dopamine would; this excites the neuron, causing an electrical charge to go down the axon to create real dopamine at the next synapse.
Over time, the neurons in the reward pathway start to change, developing fewer dopamine receptors. This is called a hypofunctioning reward system: the brain realises too many dopamine receptors are being stimulated so it starts shutting them down. This reduces your anility to feel rewarded by the drug but also by normal stimuli, like food or sex. The brain needs to produce more dopamine to maintain normal mood states, which is why nicotine is addictive: your brain comes to depend on it to maintain its dopamine levels.
Amphetamines like cocaine are illegal drugs that also involve dopamine in the synapses. However, instead of mimicking dopamine, cocaine shuts down the re-uptake of dopamine. This means the brain's own dopamine stays in the synapse, over-stimulating the dopamine receptors and producing feelings of euphoria (joy). As with nicotine, the long term effects of the drug is desensitisation. The number of dopamine receptors goes down, creating addiction because the brain needs more cocaine to make the reward pathway work.
Cannabis works differently. The drug binds to cannabinoid receptors in various parts of the brain, blocking them so that the neurons don't become excited. There are cannabinoid receptors in the hippocampus, which makes it difficult to form memories when they are blocked. Cannabis also blocks the production of a neurotransmitter called GABA, which "switches off" dopamine production. With less GABA in the reward pathway, there is more dopamine, and hence the "high" associated with the drug.
Alcohol is a legal drug that has many effects. It blocks serotinin receptors. Since serotonin calms the brain and inhibits mood, blocking serotonin receptors lifts our mood and makes us uninhibited.
Alcohol is also linked to aggression. Stephanie Gorka et al. (2013) used MRI scans to study activity between the prefrontal cortex (which handles decision making) and the amygdala (which handles emotions). The participants who had taken alcohol showed less brain activity than a control group. This suggests alcohol interferes with the brain's ability to pass information between the emotion centre (the amygdala) and the decision-making centre (the prefrontal cortex).
Nicotine is another legal drug and seems to affect dopamine receptors in a part of the brain called a "reward pathway". The nicotine binds to the receptors the way dopamine would; this excites the neuron, causing an electrical charge to go down the axon to create real dopamine at the next synapse.
Over time, the neurons in the reward pathway start to change, developing fewer dopamine receptors. This is called a hypofunctioning reward system: the brain realises too many dopamine receptors are being stimulated so it starts shutting them down. This reduces your anility to feel rewarded by the drug but also by normal stimuli, like food or sex. The brain needs to produce more dopamine to maintain normal mood states, which is why nicotine is addictive: your brain comes to depend on it to maintain its dopamine levels.
Amphetamines like cocaine are illegal drugs that also involve dopamine in the synapses. However, instead of mimicking dopamine, cocaine shuts down the re-uptake of dopamine. This means the brain's own dopamine stays in the synapse, over-stimulating the dopamine receptors and producing feelings of euphoria (joy). As with nicotine, the long term effects of the drug is desensitisation. The number of dopamine receptors goes down, creating addiction because the brain needs more cocaine to make the reward pathway work.
Cannabis works differently. The drug binds to cannabinoid receptors in various parts of the brain, blocking them so that the neurons don't become excited. There are cannabinoid receptors in the hippocampus, which makes it difficult to form memories when they are blocked. Cannabis also blocks the production of a neurotransmitter called GABA, which "switches off" dopamine production. With less GABA in the reward pathway, there is more dopamine, and hence the "high" associated with the drug.
Excellent 10 minute video which sums up neurotransmitters, drugs and addiction - including addiction to things like gambling
MEMORY & DEMENTIA
Plasticity is the term used to describe how the brain changes each structure in response to stimuli; because the brain is plastic, it can change in response to our experiences, which is how memories are stored.
Dementia is a disease which involves the shrinking of brain tissue. Because different people experience shrinking in different parts of the brain, the early symptoms tend to be different from person to person, but as the damage spreads across the whole brain, sufferers tend to show similar later symptoms.
The hippocampus is a key brain structure for memory formation and the temporal lobe seems to be important for storing and retrieving long term memories. The case of H.M. shows the importance of the hippocampus, because this was the part of the brain removed during H.M.s brain surgery, after which he could no longer create new long term memories. The Cognitive Contemporary Study by Schmolck et al. (2002) shows that the medial temporal lobe (MTL) is important for semantic long term memory and the more damaged this was, the more the patients struggled with semantic LTM.
Dementia is a disease which involves the shrinking of brain tissue. Because different people experience shrinking in different parts of the brain, the early symptoms tend to be different from person to person, but as the damage spreads across the whole brain, sufferers tend to show similar later symptoms.
The hippocampus is a key brain structure for memory formation and the temporal lobe seems to be important for storing and retrieving long term memories. The case of H.M. shows the importance of the hippocampus, because this was the part of the brain removed during H.M.s brain surgery, after which he could no longer create new long term memories. The Cognitive Contemporary Study by Schmolck et al. (2002) shows that the medial temporal lobe (MTL) is important for semantic long term memory and the more damaged this was, the more the patients struggled with semantic LTM.
The hippocampus is needed for retrieval of memories from longer ago. This is why someone in the earlier stages of Alzheimer's may remember childhood memories but not memories from earlier that day.
In Alzheimer's disease (a type of dementia), the amygdala is usually affected later than the hippocampus so the emotional aspects of something may be recalled even if the facts can't be remembered. This may make Alzheimer's sufferers more emotional and illogical.
As the disease damage spreads through the brain, more areas become affected. The cerebral cortex thins (so memories from longer ago are lost) and the brain shrinks. Damage to the left hemisphere is linked to problems with semantic memory and language, so someone may struggle to find the right word for something.
Damage to the visual system in the temporal lobes makes it harder to recognise familiar faces. However, because the pathways for vision and hearing are separate, an Alzheimer's sufferer may still know who a person is once they hear them speak.
As the damage spreads to the frontal lobes, someone with Alzheimer's may struggle with decision-making. More complex tasks, like following a new recipe, often become harder.
However, many abilities are kept, particularly those acquired long ago. Procedural memories such as dancing or playing the piano are mostly stored deep within the brain and these skills often last the longest.
In Alzheimer's disease (a type of dementia), the amygdala is usually affected later than the hippocampus so the emotional aspects of something may be recalled even if the facts can't be remembered. This may make Alzheimer's sufferers more emotional and illogical.
As the disease damage spreads through the brain, more areas become affected. The cerebral cortex thins (so memories from longer ago are lost) and the brain shrinks. Damage to the left hemisphere is linked to problems with semantic memory and language, so someone may struggle to find the right word for something.
Damage to the visual system in the temporal lobes makes it harder to recognise familiar faces. However, because the pathways for vision and hearing are separate, an Alzheimer's sufferer may still know who a person is once they hear them speak.
As the damage spreads to the frontal lobes, someone with Alzheimer's may struggle with decision-making. More complex tasks, like following a new recipe, often become harder.
However, many abilities are kept, particularly those acquired long ago. Procedural memories such as dancing or playing the piano are mostly stored deep within the brain and these skills often last the longest.
3 minute video gives a step-by-step guide to the progress of Alzheimer's through the brain
Dopamine plays an important role in memory formation. Dopamine is an excitatory neurotransmitter that causes excitement and pleasure but it's real job is to make our brain pay attention to experiences and remember them. Dopamine originally functioned to make us go back to important behaviours (like eating or sex) and stay away from dangerous behaviours (like being chased by bears).
A study by Lifen Zhang et al. (2004) shows that dopamine levels are low in the brains of Alzheimer's sufferers. Medication and diet can be used to slow down the re-uptake of dopamine and this can reduce the symptoms of the disease.
A study by Lifen Zhang et al. (2004) shows that dopamine levels are low in the brains of Alzheimer's sufferers. Medication and diet can be used to slow down the re-uptake of dopamine and this can reduce the symptoms of the disease.
5 minute video that clearly explains dopamine's influence on memory and learning
|
EXEMPLAR ESSAY
|