Lesson 3 Flashcards
What is the localisation of brain function?
the theory that different areas of the brain are responsible for different behaviours or actions.
What is the holistic theory?
holistic theory - said that all parts of the brain were involved in processing of thought and action.
during the 19th century it was discovered that certain areas of the brain held a particular function.
This is known as localisation of brain function.
What is the hemisphere?
- the brain is divided into 2 hemispheres.
- some of our physical and psychological function are controlled / dominated by a particular hemisphere known as hemispheric lateralisation.
- left hand side of the body is controlled by the right side of the brain whilst the right side of the body is controlled by the left side of the brain.
What are the function of the four lobes?
frontal lobe: speech comprehension, language, movement, thought and learning.
temporal: involved in auditory/ hearing ability and memory acquisition.
occipital: processes visual info
parietal: processes sensory info such as touch, temperature and pressure.
What is the cerebral cortex?
- it is the outer layer of the cerebrum and made up of grey matter.
it is divided into 4 lobes of the brain: the frontal , parietal , occipital and temporal. - each lobe has a particular function.
What is the motor cortex?
located in the frontal lobe
both hemispheres have one.
responsible for controlling voluntary movements.
injury to the motor cortex could result in loss of muscle function or severe trauma could lead to paralysis. This occurs on the opposite side of the body to the damage due to contralaterality.
What is the somatosensory cortex?
located at the front of the parietal lobe. it is separated from the motor cortex by a valley called the central sulcus.
the SC is where sensory info from the skin is represented.
located in both hemispheres.
the amount of somatosensory area devoted to a particular body denotes it’s sensitivity e.g. receptors for our face and hands occupy half of the somatosensory area.
What is the visual cortex?
- located in the occipital lobe at the back of the brain in the visual cortex in both hemispheres.
- each eye sends information from the right visual field to the left visual cortex and from the left visual field to the right visual cortex.
- it recieves and processes visual info and contains diff areas with each area processing different types of visual information e.g. colour, shape or movement.
- damage leads to partial or complete loss of vision called cortical blindness. Damage to one cortex, will lead to a loss of vision in the opposite visual field.
What is the auditory cortex?
temporal lobes house the auditory area / cortex in both hemispheres.
role is to analyse, interpret and process acoustic info.
damage may produce partial hearing loss, the more extensive the damage, the more extensive the loss.
What is the Broca’s area?
- discovered by Paul Broca who treated a patient who is referred to as ‘Tan’ because that was the only syllable he could express.
- he had an unusual disorder, he could understand spoken language however was unable to speak or express thoughts in writing.
- the Broca’s area is located in the frontal lobe of the left hemisphere.
- responsible for speech production.
- damage to the area - Broca’s aphasia - characterized by speech which is slow, laborious and lacks fluency.
What is wernicke’s area?
discovered by Carl Wernicke
described his patients as being able to produce language but sever difficulties understanding it. Their speech was fluent but meaningless.
located in the left temporal lobe in the left hemisphere.
responsible for language comprehension
damage to the area - wernicke’s aphasia is characterised as the impaired ability to grasp the meaning of spoken words and sentences but able to produce connected and fluent speech.
Evidence from neurosurgery
a strength of the localisation theory is that damage to an area of the brain has been linked to mental disorders.
eg dougherty et al reported on 44 OCD patients who had undergone a cingulotomy - a neurological procedure that involved lesioning of the Cingular gyrus.
post surgical follow up after 32 weeks a third had met the criteria for a successful response to the surgery and 14% for partial response.
therefore, these procedures have revealed that symptoms associated with disorders are localised.
Brain scanning evidence
strength of the localisation theory is brain scanning evidence.
Peterson et al demonstrated that wernicke’s area is active during a listening task and the Broca’s area is active during a reading task.
additionally, LTM studies have revealed semantic and episodic memories reside in diff parts of the prefrontal cortex, both studies suggest that everyday behaviours are localised in specific brain regions.
therefore, objective methods for measuring brain activity has provided scientific evidence that brain functions are localised.
case study evidence
strength - is case study evidence which supports the idea that neurological functions are localised.
unique cases like phineas gage who suffered from extensive brain damage as a result of an explosion which led to a metre length pole going through his left cheek and affected his frontal lobe.
this led to a change in personality as gage went from rational to losing social inhibition.
therefore this demonstrates how the frontal lobe is associated with regulating mood, supporting the idea that diff parts of the brain are responsible for diff functions.
However, case studies focus on unique cases like Gage which results in a low sample size and therefore cant generalise findings to the population.
High cognitive processes are not localised.
a limitation of the localisation of function theory is that higher cognitive functions such as processes involved in learning are not localised but distributed in a more holistic way in the brain.
for eg lashley removed areas of the cortex (10 - 50%) in rats that were learning a maze. No area was suggested to be more important than any other area in terms of the rat’s ability to learn the maze.
this research highlights the process of learning appears in every part of the cortex, rather than being confined to a particular place or area.
therefore, this seems to suggest that learning is too complex to be localised and requires the involvement and integration of the whole brain.
