Lesson 6: localisation of function biopsych

Question 1

Define localisation of function

Answer 1

Refers to the principals that functions have specific locations within the brain

Question 2

Define contralateral organisation

Answer 2

Two hemispheres of the cerebrum control the opposite side of the body

Question 3

What does the left hemisphere of the cerebrum control?

Answer 3

Controls movement, sensations, visual and auditory processing of the right side of the body

Question 4

What does the right hemisphere of the cerebrum control?

Answer 4

Controls movement, sensations, visual and auditory processing on the left side of the body

Question 5

Where is the motor cortex located?

Answer 5

Frontal lobe of both hemispheres

Question 6

What is the motor cortex responsible for?

Answer 6

Voluntary movements
Different parts of the motor cortex control different parts of the body
These areas are arranged logically next to one another

Question 7

What can damage to the motor cortex cause?

Answer 7

loss of muscle function/ paralysis in one or both sides of the body depending on which hemisphere has been affected

Question 8

Where is the somatosensory cortex located?

Answer 8

parietal lobe of both hemispheres

Question 9

What is the somatosensory cortex responsible for?

Answer 9

Processing sensations of pain and pressure

Question 10

Where is the visual cortex located?

Answer 10

occipital lobe of both hemispheres

Question 11

What is the visual cortex responsible for?

Answer 11

processes information such as colour and shape

Question 12

How does visual processing work?

Answer 12

light enters the retina and strikes the photoreceptors
nerve impulses from the retina are transmitted to the brain via the optic nerve
the majority terminate in the thalamus which acts as a relay station passing information onto the visual cortex

Question 13

Where is the auditory cortex located?

Answer 13

temporal lobe of both hemispheres

Question 14

What is the auditory cortex responsible for?

Answer 14

processing information such as pitch and volume

Question 15

How does the auditory pathway work?

Answer 15

begins in the cochlea in the inner ear where sound waves are converted to nerve impulses which travel via the auditory nerve to the auditory cortex
basic decoding occurs in the brain stem
the thalamus carries out further processing before the impulses reach the auditory cortex

Question 16

Strengths of localisation of function

Answer 16

• Phineas Gage was a 19th century railway worker who survived a severe brain injury when an iron rod was accidentally driven through his skull damaging his frontal lobe. He survived but had a dramatic change in his personality becoming rude, aggressive and unreliable.
• HM underwent brain surgery in the 50s to treat epilepsy. His hippocampus was removed. His long-term memory was affected while his short-term memory and intellectual abilities remained intact showing the hippocampus is involved in forming long-term memories
• Modern neuroimaging techniques like fMRI have supported localisation of brain function. Shown that participants that are exposed to visual stimuli have an active occipital lobe as visual cortex is working

Question 17

Weaknesses of localisation of function

Answer 17

• the equipotentiality theory ( Lashley, 1930) states that basic functions like motor control are localised, higher mental functions like memory are distributed across the cortex. he trained rats to navigate a maze and then removed different parts of their cerebral cortex. no single area was critical to the task. suggested intact areas of the brain were compensating for the damaged areas.
• Bavelier et al (1997) found that there are individual differences in which brain areas are responsible for certain functions. They found that different brain areas are activated when a person is silent reading. They have seen activity in the right temporal, left frontal, and occipital lobe so there isn’t a specific location in the brain for silent reading.