Psychology: The Brain and Neuropsychology

Signals between neurons are transmitted...

chemically

Define neuron

nerve cell

Define neurotransmitter

Chemicals that are released from one neutron to the other to pass messages

What is visual agnosia?

Lack of ability to recognize common objects and demonstrate their use in an activity.

Aim of Sperry (1968)

Roger Sperry studied the effects of cutting down the corpus callosum on 11 epilepsy patients by monitoring how they processed info with their 'split-brain'.

What is the brain?

The organ in your body made up of nerves that processes information and controls behaviour

Strengths of Sperry (1968)

- A lot of detailed info improves reliability - Procedures were kept the same for each participant, meaning data was gathered reliably and results could be compared easily

Strengths of lateralisation

- A lot of evidence to support the difference in male and female brains. - Much of it is from brain scans and lab experiments, making it scientifically relevant. - These methods allow controlled research and prevent extraneous variables. - This strengthens the explanation since the evidence is so reliable.

Weaknesses of Sperry (1968)

- A sample of 11 is too small to generalise results - Tasks performed in the lab could be artificial t.f. lack ecological validity - not many people have surgery to sever the corpus callosum so results may be useless

Procedure of Damasio et al. (1994)

- A virtual 3D replica of a skull matching Gage's was built - Actual measurements of the rod were taken and compared to the skull to determine its likely path (by matching possible entry and exit points) - In total, 20 different entry points and 16 different exit points were tested - With 5 likely paths, they mapped out which areas would have been damaged

Aims of Damasio et al. (1994)

- Build a model of Gage's skull using his actual skull - Identify which parts of his brain were most likely to have been damaged - Discover if any other areas had been damaged

What are the types of neurotransmitter

- Dopamine - Serotonin - GABA (gamma-aminobutyric acid)

Conclusions of Sperry (1968)

- Each hemisphere could work perfectly well on its own - Each hemisphere seemed to have its own memories which could not be shared without corpus callosum. This made it difficult for participants to perform some tasks supporting the idea that the right and left hemispheres have different roles - Left controls language, right controls spatial

Weaknesses of Damasio et al. (1994)

- Information was still gathered over 150 years ago and may not be very accurate - Brain damage was unique to Gage, so generalising info may be difficult, making the study not very useful.

Strengths of Damasio et al. (1994)

- Researchers used up-to-date tech, making it more scientific. Computer model allowed evidence to be seen rather than theorised - Doctors and researchers can predict what would happen to patients suffering similar brain damage, leading to better treatment

Results of Damasio et al. (1994)

- There was likely to be damage in both hemispheres of Gage's frontal lobe - The frontal lobe was the only area damaged - The underlying white matter in the left hemisphere was likely more damaged than the right - Damage in both hemispheres seemed to be worse in the ventromedial regions while the dorsolateral regions were less likely to be affected

Role of left hemisphere

- auditory info form right ear - processing language - controls ability to write and understand language - logical thinking - right hand - right visual field *contains Broca's area: controls production and processing of speech

Role of right hemisphere

- auditory info from left ear - spatial awareness - controls ability to recognise and perceive faces - processing music - creativity - making sense of visual info - emotional language - left hand - left visual field

Function of the frontal lobe

- decision making - impulse control - problem-solving skills - concentration - paying attention *contains motor cortex: Controls voluntary movements of the human body

Function of temporal lobe

- hearing and understanding speech, language - creating speech - Producing and processing sound-based info

Function of parietal lobe

- perception e.g. recognising faces *contains somatosensory cortex: responsible for senses

Function of occipital lobe

- vision - process visual info - understand what we see

Describe neurotransmission

An electric signal is sent from a dendrite down the axon to the vesicles containing neurotransmitters. The neurotransmitters are released out of the terminal button, carrying a chemical signal to the receptors of the next neuron across the synaptic gap.

Weaknesses of lateralisation

Evidence has some weaknesses: - In Rilea et al. (2005) study, males did not always do better on spatial tasks - Spatial tasks did not require a lot of 'right-brain' activity - How males and females used the right hemisphere cannot account for lateralisation differences

What is prosopagnosia?

Face blindness. Inability to identify an individual by their face.

Brain lateralisation in males and females

Females: - better at language skills - thicker corpus callosum: more efficient communication between the hemispheres Males: - better at spatial skills - tend to show a dominance for hemispheres - better at logical thinking

Conclusions of Damasio et al. (1994)

Gage's personality changes were compared to the damaged areas: * Ventromedial area of frontal lobe is important for making sensible decisions, controlling our impulses and emotions - This evidence supports other findings from other, similar cases - Damasio et al. had 12 other patients who suffered similar frontal lobe damage experience the same problem with impulse and emotion control This data can help predict the behaviour of someone who suffers similar brain damage

What does dopamine do?

Plays a role in attention and learning. A lack of dopamine can make it difficult to concentrate

What does GABA do?

Plays a role in calming us down. When we feel stressed we produce GABA

What does serotonin do?

Plays a role in mood. A lack of serotonin can lead to depression.

What is the role of the central nervous system (CNS)?

The CNS is made up of the brain and spinal cord. It helps the brain communicate with the spinal cord by passing messages back and forth. The brain processes the information and then sends the message down the spinal cord to make the body react.

What is the role of the peripheral nervous system?

The PNS carries out the action the brain sends through nerves

Sperry (1968) tasks

Visual task: - Screen with info on left and right visual field - 2 different words or pictures - Left eye -> Right image Right eye -> Left image - Participants had to say the words or pictures they saw Sense of touch task: - Participants had to identify an object from touch alone by placing it one hand/placing it in a pile and asking them to feel for it

Results of Sperry (1968)

Visual test: Words shown to the right visual field (left hemisphere) were repeated back. However, words shown to the left visual field hd trouble being repeated. Touch task: Objects held by right hand could be named but not ones held by the left hand. Two different objects in both hands could not be recognised unless it was the same hand

What is the role of the corpus callosum?

allows communication between the two hemispheres of the brain, making it easier for the brain to pass messages across areas and connect different info

What is lateralisation?

division of labor between hemispheres

Signals within neurons are transmitted...

electrically

What is the corpus callosum?

the thick bundle of nerve fibers that connects the hemispheres of the brain