Biopsychology pt 2 -Psychology

What is a fMRI- functional magnetic resonance imaging?

Detects blood oxygenation changes and flow that occur due to neural activity. Produces 3D images whilst asked to complete a task (e.g. reading/ listening) compare task blood flow to resting blood flow.

What is an EEG- electroencephalogram?

Measure electrical activity in the brain by recording brainwave patterns. Used to identify unusual patterns to indicate neurological abnormalities such as epilepsy, tumours and sleep disorders.

What is an ERP- Event-related potentials?

2nd EEG measurement in response to a stimulus.

Associated with specific neural, sensory and motor responses, by isolating this information and leave the relevant responses that relate to specific processes. What remains is an event-related potential- these brainwaves are triggered by specific events.

Steps:

1. Put EEG cap in saline solution to increase conductivity.

2. Measure diameter of the scalp

3. Place cap on head tightly

4. Adjust electrodes or add more solution. 

What is a post-mortem examinations?

Analysis of the brain after someone has died. Completed on those with rare illnesses to identify possible causes of the affliction the person suffered from, comparing the brain to an unaffected brain.

What are the strengths and weaknesses of fMRI?

S= Don’t use radiation unlike PET scans. Virtually risk free and straightforward to use. The images are high in resolution and show a great deal of detail and clear picture of localisation in the brain.

W= Expensive and only get a clear image if the person remains perfectly still. Only measure blood flow to the brain and not specific neuronal activity.- difficult to see exactly what type of brain activity is being represented on screen.

What are the strengths and weaknesses for EEG?

W= too general and not useful in pinpointing the specific source of neuronal activity- researchers can’t tell where some activities are specifically based in the brain.

S=Proven valuable in diagnosing disorders, such as epilepsy- random bursts of activity can be easily detected using this technique. Contribute to our understanding of the stages of sleep. EEG technology can detect brain activity at a resolution of a single second.

What are the strengths and weaknesses of ERP?

S= brings more specific measurement of neural processes at work. ERP information is derived from EEG information it has excellent temporal resolution- led to widespread use in looking at cognitive functions and deficits.

W= Not standardised, difficult conform findings. To get accurate reading background noise and other extraneous material need to be eliminated, which isn’t easy to do. 

What are strengths and weaknesses about a post mortem?

S= Broca and Wernicke both relied on post-mortem evidence in their research- provide medical knowledge and help generate hypotheses for further study.

W= Observed damage not linked to the actual deficit of the individual but could be caused by other traumas or brain decay. There is an issue of consent- people cannot give consent after their death. For example, HM, whose memory was damaged, couldn’t give fully informed consent, but his brain was studied anyway.

What is spatial resolution?

Accuracy of the scan in terms of pinning the activity shown to a specific area of the brain.

What is temporal resolution?

Accuracy of the scan in terms of the time that activity was detected.

How is a fMRI in investigating the brain?

SR= Good due to clear picture

TR= Poor- 5 secs lag thought between the initial neuronal firing and image being produced.

Ethical concerns= issues of claustrophobia, yet safter than PET scans- no radioactivity

Cause and effect= low due to time between neuronal activity and measurement.

How is an EEG+ERP in investigating the brain?

SR= Poor- doesn’t enable people to see where the activity is happening.

TR= Good- no lag between the activity and the recording. Recording can be in milliseconds- less interference between thought and output.

Ethical concerns= Very ethical-records brain activity passively, no injection or interference.

Cause and effect= EEG- short amount of time between neural activity and output- high cause and effect.

ERP- response to a stimulus- issues with cause and effect- can’t be sure that brain in change is in response to stimulus.

How is a post mortem in investigating the brain?

SR= n/a

TR= many years between diagnosis and death

Ethical concerns= consent is key- some patients might not have the capacity to consent- ethical limitation.

Cause and effect= lowest- very long time between diagnosis and death - treatments, life experiences which could change brain shape.

What is localisation?

Different parts of the brain perform different tasks and are involved with different parts of the body.

What and where is the Motor area?

• Back of frontal lobe (Both H)

• Voluntary movement of opposite side of the body. Damage- possible loss of fine motor movement.

What and where is the Somatosensory area?

• Front of both parietal lobes. Separated from motor area by a “valley“ called central sulcus

• Sensory info from skin (touch, heat and pressure) devoted to particular body part, denotes sensitivity.

What and where is the Auditory area?

• Temporal lobes

• Analyses speech-based info. Damage-partial or extensive hearing loss

What and where is the Visual area?

• occipital lobe at the back of the brain.

• Each eye sends info from right visual field to the left visual cortex and vice versa. Damage- in left H can produce blindness in part of right visual field.

What and where is the Broca’s area?

• Left hemisphere and left frontal lob

• Responsible for speech production. Damage- Broca’s aphasia which is characterised by slow speech and lacks fluency

What and where is the Wernicke’s area?

• Left Hemisphere and left frontal lobe.

• Responsible for understanding language. Damage- Wernicke’s aphasia where patients will produce nonsense words (neologisms)

What are the strengths of localisation of function?

P= Scientific evidence from Brain scans

E= Peterson et al (1988) scanned brains to demonstrate Wernicke’s area being active during a listening task, and Broca’s area active during a reading task.

L= This means that the listening task is understanding language, activating W’s area, and the reading task is speech production, activating B’s area- supporting localisation to certain areas of the brain.

P= Evidence from case studies

E= Phineas Gage- left frontal lobe damage as a pole went through his left cheek. Became quick-tempered/ rude- change temper could suggest that the frontal lobe regulates mood- supports localisation.

H= Very small sample size of 1 person- extremely difficult to generalise localisation to everyone with brain damage. Trauma could cause the mood changes, not the biological changes.

What are the weaknesses of localisation?

P= More recent evidence suggests that the human brain is actually fairly “plastic“

E= After trauma the brain appears to correct itself with stroke patients, for example, recovering the power of speech after damage to the Broca’s or Wernicke’s area. Often different areas of the brain will take over from a damaged area (recruitment of homologous area) and start to complete the function instead.

L=This shows that various parts of the brain can take over/ adapt other functions from localised parts of the brain.

P=Research from Lashley (1950) indicates that learning processes (higher mental functions) may be holistic rather than localised

E= In his studies with rats, he discovered that when areas of the cortex were removed no areas was seen to be more important the any of the others, which indicates that all of the areas are important in learning rather than just one- equipotentiality theory (equal potential to understand)

L= Rats have significantly less neurons in the cortex than humans- shouldn’t be making these generalisations. 

What is Hemispheric Lateralisation?

Refers to the 2 halves (hemispheres) of the brain are functionally different and that some behaviours and mental processes are mainly controlled by one hemisphere.

What is lateralised functions?

Function is performed by one hemisphere rather than the other.

What is contralateral functions?

Cross wired- e.g. right H controls the left side and vice versa

What is ipsilateral functions?

Opposite and same sided- e.g. in the eye there is both same sided and opposite sided control.

What is the AO3 for Hemispheric Lateralisation?

P= Lateralisation in the “normal brain“

E= Fink et al (1966) used PET scans to find out which areas were active during a visual processing task. When ppts were asked to focus on the global image (picture of whole forest) parts of the right H were much more active. Whereas, when people focused on the finer details (individual trees) parts of the left hemisphere were more active.

L= This means that the right side is more active during a whole global image, whilst left side is responsible for finer details- easier to generalise because its on a neurotypical brain and easier to create nomothetic laws.

P=Is there a “dominant hemisphere“ within the brain?

E= Nielson et al (2013) analysed brain scans from over 1000 people aged 7-29 years and found that certain hemispheres were used for different tasks, however, there was no evidence of a dominant side in the ppts

L= Supports lateralisation- certain Hs used for different tasks (large sample). But no support for dominance- right or left side isn’t more dominant.