LOCALISATION OF FUNCTION Flashcards
Broca’s area
> Speech production
Identified by Broca in the 1880’s, in the left frontal lobe.
Damage to this area causes Broca’s aphasia which is characterised by speech which is slow, laborious and lacking in fluency.
Broca’s patients may have difficulty finding words and naming objects
People with Broca’s aphasia have difficulty with prepositions and conjunctions (eg. ‘a’, ‘the’, ‘and’)
Wernicke’s Area
> Language understanding
Identified by Wernicke in the 1880’s, in the left temporal lobe.
People with Wernicke’s aphasia produce language but have problems understanding it, so they produce fluent but meaningless speech
They’ll often produce nonsense words (neologisms) as part of the content of their speech
Motor Area
> At the back of the frontal lobe (both hemispheres).
Controls voluntary movement.
Damage may result in loss of control over fine motor movements
Somatosensory Area
> At the front of the parietal lobes
Processes sensory information from the skin (touch, heat, pressure, etc.)
The amount of somatosensory area devoted to a particular body part denotes its sensitivity.
Visual Area
> In occipital lobe at the back of the brain
Each eye sends information from the right visual field to the left visual cortex, and from left visual field to the right visual cortex.
Auditory Area
> In the temporal lobe.
Analyses speech-based information.
Damage may produce partial hearing loss - the more extensive the damage, the more serious the loss
Localisation theory
> Specific areas of the brain are linked with specific physical and psychological functions
If an area of the brain is damaged through illness or injury, the function associated with that area is also affected.
Holistic theory
> In the early 19th century holistic theory suggested all parts of the brain were involved in processing thought and action
This was replaced by localisation theory
Lateralisation
> Some physical and psychological functions are controlled by a specific hemisphere
Generally, the left side of the body is controlled by the right hemisphere, the right side of the body is controlled by the left hemisphere
Cerebal cortex
> Covers the inner parts of the brain
3mm thick, is what separates us from lower animals and is highly developed.
Cortex appears grey due to the location of cell bodies hence ‘grey’ matter’
Divided into four lobes in each hemisphere (frontal, parietal, occipital and temporal)
Frontal Lobe
Broca’s Area and Motor Area
Temporal Lobe
> Auditory Area
>Wernicke’s Area
Occipital Lobe
> Visual Area
Parietal Lobe
> Somatosensory Area
Evaluation Points, Localisation of Function
> Support from neurosurgery
Brain scan evidence supporting
Language localisation model has been questioned
Case study evidence
PEEL IT: Localisation of function, neurosurgery
P- One strength of localisation theory is support from neurosurgery
E- Neurosurgery is used to treat mental disorders eg. cingulotomy involves isolating the cingulate gyrus - dysfunction of this area may be a cause of OCD
E - Dougherty et al studied 44 people with OCD who had a cingulotomy. At follow up, 30% met criteria for successful response and 14% partial response
L- The success of these procedures strongly suggest behaviours associated with serious mental disorders may be localised
PEEL IT: Localisation of Function, Brain Scan Evidence Support
P-Another strength o localisation theory is brain scan evidence to support it
E-Peterson et al used brain scans to show activity in Wernicke’s area during a listening task and in Broca’s area during a reading task
E-Also, a study of long-term memory by Tulving et al revealed semantic and episodic memories are located in different parts of the prefrontal cortex.
L-There now exists a number of sophisticated and objective methods for measuring activity in the brain, providing sound scientific evidence of localisation of function.
PEEL IT: Localisation of function, Language localisation model
P- A limitation is the language localisation model has been questioned
E-Dick and Tremblay found that very few researchers still believe language is only in Broca’s and Wernicke’s area.
E- Advanced techniques (eg. fMRI) have identified regions in the right hemisphere and the thalamus.
L-This suggests that, rather than being confined to a couple of key areas, language may be organised more holistically in the brain, which contradicts localisation theory.
PEEL IT: Localisation of function, Case Study Evidence
P-An issue with localisation of function evidence is it is largely based on case study evidence.
E-Unique cases of neurological damage support localisation theory, eg. Phineas Gage who lost some of his brain in an explosion and his personality changed.
E-However, it is difficult to make meaningful generalisations based on a single individual and conclusions may depend on the subjective interpretation of the researcher.
L-This suggests that some evidence supporting localisation may lack validity, oversimplifying brain processes, and undermining the theory.
