Psychopathology Flashcards
What is localisation of function in the brain?
Localisation is the belief that certain areas of the brain are responsible for specific processes and behaviours.
What is the motor area?
- found in both frontal lobes - regulates and coordinates movements.
- damage to the motor cortex causes the sufferer to lose muscle function/paralysis on the opposite side of the impairment.
What is the auditory area?
- in the temporal lobe
- responsible for processing auditory information and speech.
- Damage results in hearing loss.
What is the visual area?
- in the occipital lobe
- responsible for processing visual information by sending information from right visual field to left and vice versa.
- Damage to left hemisphere results in blindness to both right visual fields of the eyes (damage to opposite hemispheres).
What is the somatosensory area?
- in the parietal lobe
- processes sensory information eg. touch, heat, pressure and limb position.
What is Wernicke’s area?
Wernicke found patients with no problem producing language but couldn’t understand it.
- speech produced was fluent but meaningless.
- because of damage to ‘Wernicke’s area’
- in the left temporal lobe
- responsible for language comprehension/understanding.
- Damage results in Wernicke’s aphasia, characterised by nonsensical words ‘neologisms’.
What is Broca’s area?
- in the left frontal lobe responsible for the production of speech.
- Damage causes Broca’s aphasia, characterised by speech problems affecting sentence formation but not understanding.
- they can only talk in short meaningful sentences which lack fluency
- have difficulty with certain words helping sentence function (e.g. ‘it’ and ‘the’).
EVALUATION of localisation of function?
Gender Bias - Broca and Wernicke only studied male patients.
There is evidence to suggest that that women may have larger language centres, thus, a larger use of language.
Communication between areas - communication between areas of the brain is more important than localisation of function. Evidence suggests that complex behaviour like language and movement involve a stimulus traveling through several brain regions before a response is made. This is a weakness because it means that the theory is an oversimplification, failing to mention the importance of communication between brain regions.
Broca’s area - Dronkers re-examined Broca’s patients with MRI scans and found that they also had damage to the surrounding areas, which may also be involved in speech production.
Wider Application - Localisation of function has positive real-life applications to understand brain damage in stroke sufferers. The loss of particular functions indicates where the stroke occurred.
What is Hemispheric Lateralisation?
- idea that each hemisphere is functionally different.
- hemispheres control the opposite side of the body.
- left side is dominant for language production and comprehension, and right side for visuospatial tasks.
- contradicts holistic theory suggesting brain functions are global using whole brain
Consequences of damage to the motor area?
- sufferer loses muscle function/paralysis on the opposite side of the impairment.
Consequences of damage to the auditory area?
hearing loss.
Consequences of damage to the visual area?
Damage to opposite hemisphere results in blindness to both opposite visual fields on both eyes
What surrounds brain hemispheres?
-covered by a cortex of ‘grey matter’.
Outline Split-Brain Research into Hemispheric Lateralisation.
A: Sperry aimed to demonstrate that hemispheres have different functions/abilities
- natural experiment investigating hemispheric lateralisation
- 11 male split-brain patients who had their corpus callosum cut, separating the two hemispheres.
P: pps had one eye covered and stared at a point on a screen
- In the describe task an image/word was presented to the patient’s left visual field for 1/10th of a second (processed by right hemisphere) or right visual field (processed by left hemisphere).
- pp had to say what they saw.
- corpus callosum relays information between hemispheres giving a complete picture.
- in split-brain patients, information isn’t relayed.
F: If the stimulus was exposed to right visual field, they could say the word
- because it was processed by opposite (L) hemisphere, containing ‘language centres’, allowing speech.
- if stimulus was exposed to the Left visual field, patient couldn’t say the word
- because it was processed by opposite (R) hemisphere with no language centres.
- In the tactile test, an object was placed in the patient’s left or right hand behind a screen. They selected a matching object from behind the screen either verbally or visually (by touch).
F: In the right hand, pps could describe the object in speech and writing
In left hand, pps unaware of the object and couldn’t verbally identify it. However, they could point/select the object visually and by touch
- Because left hemisphere produces language
- Right hemisphere cannot produce language so although it can identify stimuli, it can’t verbalise this
Conclusions of Sperry’s research?
The findings of Sperry’s research highlights key differences between the two hemispheres.
Left hemisphere is dominant in speech and language
Right hemisphere is dominant in visual-motor tasks
Outline the 2 conditions of Sperry’s research.
Describe task: image/word was presented to the patient’s left visual field for 1/10th of a second (processed by right hemisphere) or right visual field (processed by left hemisphere). The pp had to say what they saw.
In a normal brain, the corpus callosum relays information between hemispheres giving a complete picture. However, in split-brain patients, information isn’t relayed.
Tactile test: object placed in the patient’s left or right hand behind a screen. They selected a matching object behind the screen either verbally or visually (by touch).
Describe the findings of Sperry’s split-brain research for:
- the describe task
- image/word was presented to the patient’s left visual field for 1/10th of a second (processed by right hemisphere) or right visual field (processed by left hemisphere). The pp had to say what they saw.
- In a normal brain, corpus callosum relays information between hemispheres giving a complete picture.
- in split-brain patients, information isn’t relayed.
F: If the stimulus was exposed to right visual field, they could say the word
- because it was processed by the left hemisphere, containing the ‘language centres’, allowing speech.
- However, if exposed to the left visual field the patient couldn’t say the word because it was processed by the right hemisphere which contains no language centres.
Describe the findings of Sperry’s split-brain research for:
- the tactile task
- object was placed in the patient’s left or right hand behind a screen. They selected a matching object from behind the screen either verbally or visually (by touch).
F: In the right hand, pps could describe the object in speech and writing
- In left hand, pps unaware of the object and couldn’t verbally identify it.
- they could point/select the object visually and by touch
- Because only left hemisphere produces language
- Right hemisphere cannot produce language so although it can identify stimuli, it can’t verbalise this
Positives of Sperry’s split-brain research?
- Clearly demonstrates lateralisation, opposing holistic theory of whole brain being involved in tasks.
- left hemisphere dominant for language tasks and right for visuo-spatial tasks.
- suggests left hemisphere is the analyser and right is the synthesiser- with individual and specific functions.
- standardised procedures (1/10th of a second to look at pictures) Thus, high control enables the procedure to be regarded as replicable to assess reliability.
Negatives of Sperry’s split-brain research?
- Findings cannot be be generalised to NORMAL brains as sample size of only 11 pps with epilepsy is not representative of the rest of the population and may only reflect epileptic brains.
- Lack of control over extraneous variables as some patients had more disconnection of hemispheres as part of the surgical procedure than others. This may have affected the degree that information was relayed between hemispheres.
- Furthermore, some patients received drug therapy for longer than others, affecting their ability to recognise objects due to biological neuronal changes.
- These confounding variables were not controlled, meaning that lateralised functions may be unreliable as causal conclusions were drawn.
- data was artificially produced as the mundane task of identifying objects is unreflective of the everyday and, in real life, a severed callosum can be compensated for by the use of two eyes (not covered).
- Gender-biased all-male sample may not demonstrate differences between the sexes, so we cannot generalize results to women who may have eg. larger visual fields.
Discuss how hemispheric lateralisation/language centres have helped us understand the brain.
- systematic research from Wernicke and Broca demonstrated that language centres are lateralised to the left hemisphere
- Wernicke’s area is responsible for the interpretation of speech and Broca’s for the production of speech
- Damage leads to Wernicke’s + Broca’s aphasia, characterised by inability to understand or produce speech
- As language centres are lateralised, they are not impaired by damage to the right hemisphere.
- The left hemisphere controls muscles on the right side of the body
- thus, damage to the left hemisphere causes impaired language and right-sided paralysis of body muscles
What is plasticity?
Plasticity is the brain’s ability to physically and functionally adapt and change through a person’s life
- as a result of new learning, experiences and trauma.
- creates new neural pathways and alters existing ones.
- frequently used connections are strengthened
- rarely-used connections are removed in a process called synaptic pruning to increase the efficiency of neuronal transmissions.
Research support for brain plasticity?
Maguire’s study of the brains of London taxi drivers:
- MRI scans found a larger volume of grey matter in the hippocampi of their brains than control group
- and positive correlation between increasing grey matter volume and the longer the individuals had been taxi drivers.
- Researchers concluded that grey matter in the hippocampus facilitates navigation because it is associated with spatial awareness; an ability which taxi drivers must have when they complete The Knowledge test.
- shows that the structure of the brain can be altered by plasticity due to increased demands for specific skills.
What is functional recovery?
- A form of plasticity that occurs after trauma, where the brain transfers functions of damaged areas to healthy parts of the brain
- adapting to compensate for damage quickly after trauma in spontaneous recovery to allow normal functioning.
