Psychology Topic 4: The Brain and Neuropsychology

How does your brain affect you?

Brain

The organ in your head

• Made up of nerves that process info + controls complex behaviour

Hemisphere

**Half** of the brain

* Right hemisphere on the right side
* Left hemisphere on the left

Cerebrum

**Largest** part of the brain where **higher processing** happens

* **Upper** part of the brain
* **Has an** outer cortex

Cortex

**Outer layer** of the brain (a ‘shell‘)

* Has lots of **folds** to i**ncrease its surface area**

Technical terms for:

* The ‘bumps‘ on the surface
* Creases on the surface

* Gyri (‘a gyrus’)
* Sulci (‘a sulcus’)

What does the large surface area allow the human brain to have?

More **nerve cells**

* This allows it to **control more functions**

Why are the surfaces of animal brains smoother than a human brain?

Animals have **fewer** **behavioural** **functions** than humans

* So the need less surface area in the brain

Spinal cord

A **pathway of nerves** inside the spine

* It **connects** the brain to the rest of the **body** through the **peripheral nervous system**

Brainstem

The part of the brain that connects the **spinal cord** to the **upper brain**

* Controls **reflexes**

Reflexes

**Actions** that are **automatic**

* They don’t require conscious thought

Frontal lobe

The area at the front of the brain responsible for decision-making + impulse control

• Helps control problem-solving skills

• Helps us concentrate and pay attention to different activities

Motor cortex

* Towards the **back** of the **frontal lobe**
* A large area just in **front** of the central sulcus
* Plays a key role in the **voluntary movements**

Central sulcus

The **crease** that **separates** the **frontal lobe** from the **parietal lobe**

Temporal lobe

The area on the side of the brain that controls hearing + memory

• Helps hear/understand sounds

• Helps understand /create speech

• Contains the auditory cortex (controls hearing)

Parietal lobe

The area at the top of the brain important for perception and sensations of touch

• Contains the somatosensory cortex- sense of touch

Occipital lobe

The area at the **back** of the brain that controls **vision**

* Contains the **visual cortex**
* Helps us **process visual information** from our eyes
* Helps make sense of this information so we **understand** what we are seeing

Cerebellum

An area of the brain near the **brainstem** that controls **motor movements**

* Vital role in **motor skills**- movement, coordination and balance
* Takes information from the senses, spinal cord and other parts of the brain and then combines them to coordinate behaviour
* The message is sent via the spinal cord

How does the cerebellum coordinate behaviour if we are running and see an object in our way?

1. The cerebellum combines this information and sends a message back to the body
2. It tells it to move to avoid the object.
3. This message is sent via the spinal cord
4. It tells us to change direction while helping us keep our balance
* So we do not fall as we dodge the object in our way

Structure of the brain

Lateralisation of function

* The different jobs performed by each half of the brain
* Each hemisphere will have different specialist roles

How is the brain asymmetrical?

• 2 hemispheres of brain = not exactly the same, in terms of structure + function

  • Each hemisphere controls diff functions + plays a larger or smaller role in a particular behaviour

What side of the brain controls each side of the body?

* Each side of the brain controls the functions on the opposite side of the body
* Right side of the brain controls functions on the left side of the body

Corpus callosum

• A thick bundle of nerve fibres that connect the right + left hemisphere of the brain so they can communicate w each other

• So whole brain can work as 1 complete organ

  • The 2 hemispheres retain their own roles while working together to control behaviour in the whole body

Broca’s area

A part of the left hemisphere of the brain that controls speech production

What does the left hemisphere control?

Logical thinking

1. Broca’s area controls the production of speech

2. BA controls nerve cells in our face that help us speak

3. Processing of language-based info

4. Ability to write + understand lang

What might happen if someone’s Broca’s area was damaged?

They will find it difficult to talk

* Stuttering
* Difficult to identify objects verbally

Spatial awareness

The ability to negotiate space + navigate our way around our environment

What does the right hemisphere control?

Creativity

1. Spatial awareness

2. Ability to recognise + perceive faces

3. Processing of music

4. Making sense of visual info that we see

How does the corpus callosum play a role when you hear something spoken in your left ear?

1. Info passes to the R hemisphere of the brain

2. Info passed to the L hemisphere to be decoded so brain understands what was said

3. Info passed to the right hand for the person to write down what they heard

Sex differences in brain lateralisation and why (what did people think before)?

(how do males and females have brains that work differently?)

1. Females → better at language skills (left-brain tasks)

   • Females may have a thicker corpus callosum

2. Males → better at spatial skills (right-brain tasks)

What does it mean if females have a thicker corpus callosum?

They use both sides of their brain for tasks

• Males show dominance for 1 hemisphere for the same tasks

  • More activity in 1 hemisphere than the other, rather than an equal spread of activity

What is the central nervous system (CNS) made up of?

* The brain
* Spinal cords

What does the central nervous system (CNS) do?

Helps brain + body communicate w one another

How does the central nervous system (CNS) work?

1. Brain sends messages to the body

2. Messages initially carried thru the spinal cord (sensory nerves)

3. Spinal cord activates the PNS

Sensory nerves

• Located in the skin, muscles or organs

• Take information into the nervous system

Peripheral nervous system (PNS)

• System of nerves that connect the CNS to the skin muscles + organs in the body

• Activated by the spinal cord

Neurotransmitters

Chemicals released from neurons that pass messages from nerve cell to another across a synapse

Neuron

A nerve cell that transmits information

Neurotransmitters and their roles

• Dopamine

• Serotonin

• GABA

1. Dopamine- attention and learning

2. Serotonin- mood

3. GABA- calms us down

When are neurotransmitters released and what happens to it?

When a nerve impulse reaches the end of a nerve fibre

• Neurotransmitter picked up by another neuron to receive the message + continue the NI

Synaptic transmission

The process by which neurotransmitters are released by a neuron, move across the synaptic gap + are then taken up by another neuron

Synapse

A gap between 2 neurons that allows messages, in the form of neurotransmitters, to pass from one cell to another

Axon

The long structure that connects the cell body of a neuron to the terminal button at the end of the cell

Terminal button

The end of a neuron

* Filled with tiny sacs called vesicles
* Contain neurotransmitters

Vesicles

Small sacs containing neurotransmitter (chemical) molecules

Receptors

Special sites on neurons that are designed to absorb neurotransmitter molecules

Synaptic functioning

1. Messages are passed throughout the nervous system, from one neuron to the next, by synaptic transmission

2. An electrical impulse is triggered inside the cell body of a neuron

3. The neuron then passes a small impulse along the axon towards the end of the nerve fibre

4. When the nerve impulse reaches the terminal button, the vesicles release the neurotransmitter molecules into the synapse

5. These molecules are ‘grabbed’ by the receptors on the next neuron to pass the message impulse on

Neurological damage

Damage to the body’s CNS and PNS

What would happen if the brain is damaged?

Messages normally passed around in the nervous system might be interrupted

Agnosia

Inability to interpret sensations → unable to make sense of the info/recognise something

• Issue in the way the brain processes sensory information

Visual agnosia

Inability to recognise things that can be seen

* Disorder of perception
* Result of damage to the parietal lobe
* Can see the object in front of them perfectly but their brain can’t make sense of this information.

Difficulties of a person with visual agnosia

Info sent from eyes to brain can’t be understood → person can’t recognise things they can see

1. Recognizing objects

   • Due to impairments in basic perceptual processing or higher-level recognition processes.

2. Understanding another person’s identity

3. Perceiving shapes or forms

Symptoms of visual agnosia

(different symptoms depending on the type of visual information the brain cannot understand)

Patients may not be able recognise:

1. The colour of an object

2. Objects and name them

3. Places they are familiar with.

Prosopagnosia

* ‘face-blindness’
* Inability to recognise faces even though they can be seen
* Eyes send information to the brain about the face, but the brain can’t recognise who the face belongs to

What can prosopagnosia be caused by?

* Damage to the fusiform face area (FFA)
* Near the back of the temporal lobe
* Next to the occipital lobe

Symptoms of prosopagnosia

Patients find it difficult to identify people by their faces

Some patients:


1. See all faces as ‘the same’ and can’t tell faces apart
2. Can’t recognise faces of people that they know really well
3. Have trouble matching up pictures of faces that they don’t know

Where is the Pre-frontal cortex located?

Area of the brain’s cortex at the very front of the frontal lobe

* Immediately behind the forehead

What does the Pre-frontal cortex control?

• Impulses, decision-making, and rational thinking

  • Stops you from doing something like hitting someone when you are angry

• Helps keep our emotions balanced so that we do not get too emotional

  • No matter what emotion we are feeling

What happens if the pre-frontal cortex is damaged?

* People can become impulsive and aggressive.
* Difficult for people to control their emotions
* So their personality changes a lot
* People are more likely to commit crimes that they would not have done before

What did Adrian Raine et al. (1997) study?

* The brains of murderers
* He compared these to a similar group of people who had not committed murder

What did Adrian Raine et al. (1997) find and what was it used to show?

There were differences in the pre-frontal cortex of the two groups.

• Murderers had less activity in the pre-frontal cortex

  • Making them more impulsive and aggressive

• Explains why some people are more prone to violent and impulsive behaviour than others

White matter

Brain and spinal cord tissue

* Consists mainly of nerve fibres (axons)
* Where neurons pass messages along axon fibres

Why do patients with severe epilepsy get surgery?

Reduce seizures/symptoms of epilepsy

* They cut down the corpus callosum to disconnect the right and left hemisphere

In the last picture, why does it not match what the person saw?

1. Someone with a split-brain cannot exchange information between the 2 hemispheres
2. So if information goes to the right of both eyes (left hemisphere) and comes into the left hand (right hemisphere) the person cannot match the two pieces of information

Quasi experiment

Aims to establish a cause and effect relationship