Localisation of function in the brain Flashcards
A01
Outline Localisation of function
Theory that specific functions of brain (e.g. language, memory, etc.) have certain locations in brain.
A01
Localisation vs Holistic theory
During 19th century, scientists Broca & Wernicke discovered the specific areas of the brain are associated with particular physical & psychological functions
However before their investigation, scientists adopted a holistic theory of the brain that all parts of the brain were involved in processing of thought & action
In contrast , Broca & Wernicke argued for localisation of function-diff parts of brain perform specific tasks- it follows that if brain damage occurs to specific area of brain- the associated function of that area would also be damaged
A01
Outline hemisphere of the brain & cerebral cortex
The brain is split into two hemispheres,
right & left hemisphere
The two hemispheres are connected by corpus callosum-which acts as a bridge between two hemispheres & allows them to send messages & work together
Each hemisphere has 4 brain lobes
* Frontal Lobe:
* Temporal Lobe:
* Parietal Lobe:
* Occipital Lobe:
There is also the cerebellum that controls balance and coordination and the brain stem, which controls involuntary responses
* The cerebral cortex is outer layer of both hemispheres
Outline Motor area- Frontal lobe
Motor Area
The motor area- located in frontal lobe(in each hemisphere) & is responsible for voluntary movements by sending signals to the muscles in the oppositie side of body
Damage to this area of brain may result in loss of control over fine movements
Outline Somatosensory area-parietal lobe
The somatosensory area is located in parietal lobe & receives incoming sensory info from the skin to produce sensations related to pressure, pain, temperature, etc.
Somatosensory area is seperated from motor area by valley called ‘central sulcus’
A01
Occipital lobe-visual area
Visual Area
At back of the brain, in the occipital lobe is visual area, which receives & processes visual info
* Info from right-hand side visual field is processed in left hemisphere,
* info from left-hand side visual field is processed in the right hemisphere.
* Damage to left hemisphere can produce blindness in part of right visual field of both eyes
Auditory area-the temporal lobe
Auditory Area
The auditory area is located in temporal lobe & is responsible for analysing & processing acoustic & speech based info
Damage to this area of brain may produce hearing loss
Damage to specific area of temporal lobe -Wernickes area may affect ability to comprehend language
A01
The language centres of the brain-Brocas area
Brocas area -area in frontal lobe in left hemisphere responsible for speech production
Language is restricted to left side of brain in most ppl
Broca, french neurosurgeon identified small area in left frontal lobe responsible for speech production
damage to Brocas area caused Broca aphasia characterised by speech lacking in fluency & slow
Broca treated a patient called tan -called this cause only word he could say
PPl with Brocas aphasia have difficulties with prepositions & conjunctions ( e.g the,and)
Language centres-Wernickes area
wernickes area-area of temporal lobe in LH responsible for language comprehension
Wernicke german neurologist -discovered area of brain involved in understanding language (langauge comprehension)
Back portion of left temporal lobe
Patients with lesions to on their Wernickes area could speak but unable to understand language
Proposed that language involved seperate motor & sensory regionslocated in diff cortical regions
A03
compelling argument against LOF is notion of Plasticity-Lashley
Limitation
A compelling argument against localisation of function is notion of plasticity. When brain has become damaged , through illness or accident & particular function is lost , rest of brain appears able to reorganise itself in attempt to recover the lost function
Lashley-described this as ‘law of equipotentiality’
where surviving brain circuits chip in so the same neurologcal action can be achieved
A03
Research support for localisation of brain function from unique case studies -phineas
Strength
phineas Gage had an accident where an iron rod blasted through his frontal lobe , the damagae to his brain left a merk on his personality from a calm to a quick tempered p
This supports idea of localisation of function & personality change can be explained by the damage to a specific area of the brain
Counterpoint:
Difficult to draw conclusions from unique events that cannot be generalised to everyday life & case studies are subjective & theres lack of control over extraneous & confounding variables has to be considered
A03
Localisation fails to take into account individual differences-Herasty
Limitation
Herasty found that women have proportionally larger Broca & wernickes areas than men
this can explain the greater ease of language used amongst women
this suggests level of beta bias -the diff between men & women ignored & variations in patterns of size & areas observed during language activities not considered
