The Brain and Neuropsychology
The structure of the human brain
- It is divided in two halves, one on the left and one on the right known as hemispheres.
- The upper part of the brain = cerebrum, this has an outer cortex.
- Large surface area allows the human brain to have more nerve cells and therefore it controls more functions.
- Brain communicates with the rest of the body through the spinal cord.
- Information passes between the brain and spinal cord through the brainstem, which controls reflexes.
The functions of the brain
| Frontal lobe Important role in decision making and impulse controlControls problem solving skills, helps us concentrate and pay attention to different activities Motor cortex : voluntary movements of the human body |
| Temporal lobeHearing and understanding sounds, understanding speech and creating speechProducing and processing sound-based informationSaid to contain auditory cortex (controls hearing)Areas that help to control memory functions |
| Parietal lobePlays a big part in perception (understanding the world around us)Gives us the ability to recognise facesThere is a large section that is in control of our sense of touch – somatosensory cortex |
| Occipital lobeAbility to seeProcess visual informationCalled the visual cortex |
| Cerebellum Vital role in movement, coordination and balance (motor skills)Takes information from the different senses, our spinal cord and other parts of the brain and combines them to coordinate behaviour |
Lateralisation of function in the hemispheres
Lateralisation of function: the different jobs that are done by each half of the brain.
Asymmetrical function
- The two hemispheres aren’t exactly the same
- Each side of the brain appears to control the functions on the opposite side of the body
- To help the two hemispheres work together, a thick layer of nerve fibres (corpus callosum) connects the right and left hemispheres. This allows the two sides of the brain to communicate.
The role of the left and right hemispheres
Left
- The left hemisphere plays a big role in the processing of language. An area called Broca’s area controls the production of speech. This area is linked to the control of the nerve cells in the face that helps us to speak
- Other areas are dedicated to the control of our ability to write and to understand language.
Right
- Large role in spatial awareness
- Parts that control our ability to recognise and perceive faces
- Often seen as being more creative
| Left hemisphere | Right hemisphere |
| Control of right handRight visual fieldSpeechUnderstanding written languageUnderstanding what is heardLogical thinking | Control of left handLeft visual fieldSpatial awareness Creativity Recognising facesMusical ability |
Role of the corpus callosum
- Thick band of nerve fibres that connects the left and right hemisphere together
- Allows messages to be passed through
Sex differences in brain lateralisation
- It was always thought that males and females have brains that work differently
- Females supposedly are better at language skills
- Males on the other hand were felt to be better at spatial tasks
- There was some evidence that females have a thicker corpus callosum, they may use both sides of their brain for some tasks
- Males tend to show dominance for one hemisphere for the same tasks
Strengths and weaknesses of lateralisation in explaining sex differences between males and females
| Strengths | Weaknesses |
| Evidence.Harasty et al (1997) suggested that parts of our brain that process and produce language are slightly bigger in females compared to males. | Evidence is mixed.Rilea et al (2005) found that males did not always do better in spatial tasks compared to females. |
| Evidence Rilea et al (2005) found that males were better at some spatial tasks , especially those that use a lot of activity in the right hemisphere. | Evidence is mixed.Sommer et al (2004) suggested that there was no strong evidence that females used both hemispheres for language tasks, meaning that this is not a good explanation for girls being better at language skills. |
| This evidence uses laboratory experiments, scientific methods, brain scans. This allows research to be well controlled and helps to prevent extraneous variables. |
The role of the central nervous system
- The CNS is made up of the brain and spinal cord.
- It helps the brain and body communicate with one another by passing messages backwards and forwards.
- Sensory nerves send messages to the brain via the spinal cord.
- Brain processes info and sends messages to the body down the spinal cord to make the body do something.
- The spinal cord can activate the peripheral nervous system [PNS], which makes the body do actions the brain tells it to do.
The function of neurotransmitters
Neurotransmitters are chemicals that are released from neurons to help them pass messages from one cell to another.
Examples:
| Neurotransmitter | Example of what it does |
| Dopamine | Plays a role in attention and learning.Not enough: difficulty to concentrate |
| Serotonin | Plays a role in mood.Not enough: feel depressed |
| Gaba | Plays a role in calming us downWhen stressed, GABA is produced to help relax us |
Synaptic functioning
- Messages are passed throughout the nervous system, from one neuron to the next, by a process called synaptic transmission.
- Synapses : tiny gaps between neurons that allow chemical messages to pass between them.
- An electrical impulse is triggered inside the cell body of a neuron, the neuron then passes a small impulse along the axon towards the end of the nerve fibre.
- At the end of the nerve fibre is the terminal button which is filled with tiny sacs called vesicles containing neurotransmitters.
- When the nerve impulse reaches the terminal button, the vesicles release the neurotransmitter molecules into the synapse.
- These molecules are then ‘grabbed’ by the receptors on the next neuron to pass the message impulse on.
The impact of neurological damage
Visual agnosia
| Description | Symptoms |
| A person not being able to recognise something that is presented to them.Visual agnosia: disorder in which a person can see perfectly well but cannot understand what they see. | Patients might not be able to recognise the colour of an object Patients might not be able to recognise objects and name themMight not recognise places |
Prosopagnosia
| Description | Symptoms |
| Face blindness They cannot recognise faces but can see them.Caused by damage to a part near the back of the temporal lobe, next to occipital called fusiform face area [FFA] | Difficult to identify facesThey see all faces the same, cannot tell faces apartSome can’t recognise faces of people they know well |
Impact of damage to the prefrontal cortex
- Prefrontal cortex helps us control our impulses
- Helps us to keep our emotions balanced so that we do not get too emotional
- If this is damaged, people can become impulsive and aggressive
- Adrian Raine et al studied the brains of murderers and compared these to people who have not committed murder
- There were differences in the prefrontal cortex
- Murderers had less activity in the prefrontal cortex, making them impulsive and aggressive
- This can be used to explain why some people are more prone to violent and impulsive behaviour.
Quiz / test yourself – Can you name the parts of the brain?
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