Localisation of Function

Question 1

Localisation of Function

Answer 1

Refers to the principle that specific functions (language, memory etc) have specific locations within the brain.

• Scientists in the early 19th Century supported the holistic theory that all parts of the brain were involved in processing thoughts and actions.
• But specific parts of the brain were later linked with specific physical and psychological functions (localisation of function theory).
• This was largely investigated through case studies of brain damage, and more recently through neuroimaging studies.

Question 2

CASE STUDY: Phineas Gage

Answer 2

• In 1848 while working on a railway line, caused an accident in which an iron bar went through his skull.
• Although Gage survived this ordeal, he did experience a change in personality, such as loss of inhibition and anger.
• This change provided evidence to support the theory of localisation of
brain function, as it was believed that the area the iron bar damaged (amygdala) was responsible for personality.

Question 3

Lateralisation

Answer 3

The brain is divided into two halves; right & left hemispheres.
• This is known as lateralisation – there is a difference in some physical and psychological functions controlled by each
hemisphere.
• Generally the left side of the body is controlled by the right hemisphere; and the right side of the body by the left hemisphere.

Question 4

Left hemisphere

Answer 4

• Sensory stimulus from right side of body
• Motor control of right side of body
• Speech, language and comprehension
•Analysis and calculations
• Time and sequencing
• Recognition of words, letters and numbers

Question 5

Right hemisphere

Answer 5

• Sensory stimulus from left side of body
• Motor control of left side of body
• Creativity
• Spatial ability
• Context / perception
• Recognition of faces, places and objects

Question 6

Cerebral cortex

Answer 6

• The cerebral cortex is like a ‘tea cosy’ covering the inner parts of the brain.
• It is about 3mm thick and is what separates us from lower animals, as it is highly developed. • The cerebral cortex appears grey due to the location of cell bodies – hence ‘grey matter’.

Question 7

Lobes

Answer 7

• Frontal Lobe (Motor Cortex) - Left: Broca’s area
• Parietal Lobe - Somatosensory cortex
• Occipital Lobe- Visual cortex
• Temporal Lobe - Auditory centres - Left: Wernicke’s Area
• Brain stem
• Cerebellum

Question 8

Motor Areas

Answer 8

Motor Cortex:
The motor area is located towards the back of the frontal lobe (in both hemispheres)and is
responsible for voluntary movements by sending signals to the muscles in the body.
Hitzig and Fritsch (1870) first discovered that different muscles are coordinated by different areas of
the motor cortex by electrically stimulating the motor area of dogs.
This resulted in muscular contractions in different areas of the body depending on where the probe was inserted.
The regions of the motor area are arranged in a logical order, for example, the region that controls finger movement is located next to the region that controls the hand and arm and so on.

Question 9

Somatosensory Areas

Answer 9

Somatosensory Cortex:
• The somatosensory area is located in the front of the parietal lobe and receives incoming sensory
information from the skin to produce sensations related to pressure, pain, temperature, etc.
• Different parts of the somatosensory area receive messages from different locations of the body, and
the amount of somatosensory area devoted to a particular body part denotes it’s sensitivity.
• Robertson (1995) found that this area of the brain is highly adaptable, with Braille readers having larger areas in the somatosensory area for their fingertips compared to normal sighted participants.

Question 10

Visual Area

Answer 10

3. Occipital Lobe:
   • At the back of the brain, in the occipital lobe is the visual area, which receives and processes visual information.
   • Information from the right-hand side visual field is processed in the left hemisphere, and information from the left-hand side visual field is processed in the right
   hemisphere.
   • The visual area contains different parts that process different types of information including colour, shape or movement.

Question 11

Auditory Area

Answer 11

Temporal Lobe:
• The auditory area is located in the temporal lobe and is responsible for analysing and processing acoustic information, (speech based information).
• Information from the left ear goes primarily to the right hemisphere and information from the right ear goes primarily to the left hemisphere.
• The auditory area contains different parts, and the primary auditory area is involved in processing simple features of sound, including volume, tempo and pitch.

Question 12

Broca’s Area

Answer 12

• Responsible for Speech production.
• Identified by Broca in the 1880, in the left frontal lobe.
• Damage to this area causes Broca’s Aphasia, which is characterised by speech that is slow, laborious, and lacking in fluency.
• Broca’s patients had difficulty finding words and naming certain objects.
• Patients with Broca’s Aphasia have difficulty with prepositions and conjunctions (e.g. ‘a’, ‘the’, ‘and’).

Question 13

Wernicke’s area

Answer 13

Responsible for language comprehension.
• Identified by Wernicke in the 1880’s in the back of the temporal lobe.
• Patients produce language but have problems understanding it, so they produce fluent but meaningless speech.
• Patients with Wernicke’s Aphasia will often produce nonsense words (neologisms) as part of the content of their speech.

Question 14

Motor cortex

Answer 14

Voluntary movements, located in frontal lobe.

• Left side of brain controls right side of bodily movements.

Question 15

Somatosensory cortex

Answer 15

Processes sensory information, located in the parietal lobe.

Question 16

Visual centres

Answer 16

Located in the occipital lobe, but begins in the retina-and activates the photoreceptors, nerve impulses then travel to the brain via the optic nerve and mostly terminate at the thalamus which acts as a relay station to the visual cortex.

Question 17

A03

Answer 17

A strength of localisation theory is that there is brain scan evidence to support it:
Peterson et al (1988)used brain scans to show activity in Wernicke’s area during a listening task, and in Broca’s area during a reading task, suggesting these areas of the brain have different functions. Also a study of LTM by Tulving (1994) revealed semantic and episodic memories are located in different parts of the frontal cortex.
Due to the large number of sophisticated and objective methods of measuring activity in the brain – there is valid evidence of the localisation of function theory.

Question 18

Equipotentiality A03

Answer 18

Not all researchers agree cognitive functions are localised in the brain
Lashley (1930) believed that motor + sensory functions localised
But ‘higher’ mental functions were not localised
Intact areas of the cortex could take over responsibility for specific cognitive functions following injury
According to this theory, effects of brain damage determined by extent rather than location of the damage

Question 19

Support for Language centres – Aphasia Studies

Answer 19

Broca’s and Wernicke’s areas – language production and comprehension
Support for these in evidence of damage to the particular area causing impaired abilities (aphasia)
i.e.
Damage to Broca’s area resulted in impaired ability to produce language
Damage to Wernicke’s area resulted in impaired ability to understand language

This demonstrates the important role played by these brain regions in different aspects of language.

Question 20

Issue and Debate

Answer 20

Inappropriately Reductionist

Inappropriately Nomothetic