The Brain

Question 1

Describe Hemispheric Lateralisation

Answer 1

Hemispheric Lateralisation refers to the fact that some mental processes are mainly specialised to either the right or left hemisphere of the brain. For example, the left hemisphere is dominant for language and speech

Question 2

Describe Split Brain Research

Answer 2

Split Brain Research is research that studies individuals who have been subjected to the surgical separation of the two hemispheres of the brain because of severing the corpus callosum.

Question 3

Sperry Procedure

Answer 3

A Study by Sperry where she presented to the left or right visual field. With their hands hidden so they could see them they responded with either their left or right hands or verbally to the images presented.

Question 4

Sperry Finding

Answer 4

Sperry Found if a picture was first shown to the left visual field, the participant did not recognise it when the same picture appeared in the right visual field.
If visual material appeared in the right visual field the patient could describe it in speech and writing.

Question 5

Sperry Concluded

Answer 5

Sperry Concluded that people with split brains have two separate visual inner worlds each with its own train of visual images.

Question 6

Evaluate Lateralisation and split brain research:

Sample Size

Answer 6

A major criticism of the procedure was Sperry’s sample. 11 participants is a very small sample, however Sperry may not have had any control over this - there may not be very many split-brain patients available to study. The small sample also enabled Sperry to gain more in-depth data The comparison group used by Sperry, was people with no inter-hemisphere disconnection, it could be argued that a much more valid group would be epileptic people who had not had their hemispheres disconnected.

Question 7

Evaluate Lateralisation and split brain research:

Ecological Validty

Answer 7

A further weakness of the study relates to ecological validity. The findings of the study would be unlikely to be found in a real life situation because a person with severed corpus callosum who had both eyes would be able to compensate for such a loss.

Question 8

Evaluate Lateralisation and split brain research:

Lateralisation Changes With Age

Answer 8

Lateralisation changes with age. It was found language became more lateralised to the left hemisphere as children aged but after the age of 25 lateralisation decreased with each decade of life. Using extra processing resources of the other hemisphere may compensate for age-related declines in function. As

Question 9

Evaluate Lateralisation and split brain research:

Language May Not Be Restricted To The Left Hemisphere.

Answer 9

As language may not be restricted to the left hemisphere as shown by a case of a split-brain patient who developed the capacity to speak out of the right hemisphere. This contradicts previous research that suggested the right hemisphere was unable to handle even the basic language functions.

Question 10

Localisation: Explain Visual Centres

Answer 10

Light enters the eye and stimulates the retina. Nerve impulses are transmitted via the optic nerve to the thalamus. The message is then transmitted to the visual cortex in the occipital lobes. Visual information from the right side is then transferred to the left hemisphere and the left side is transferred to the right hemisphere.

Question 11

Localisation: Explain Auditory Centres

Answer 11

Sound enters the ear and when the cochlea is stimulated nerve impulses then travel via the auditory nerve to the brain stem. The message continues to the thalamus the to the auditory cortex where the message is interpreted.

Question 12

Localisation: Explain Somatosensory Cortex

Answer 12

Somatosensory cortex processes sensory information from the skin.

Question 13

Localisation: Explain Motor Cortex

Answer 13

Motor cortex sends nerve impulses to the muscles. Different areas of the motor cortex control different muscle movement. Motor cortex sends nerve impulses to the muscles. Different areas of the motor cortex control different muscle movement.

Question 14

Localisation:

Broca’s Area

Answer 14

Language is in the left Hemisphere Only,

Broca’s area is involved in speech production.

Question 15

Localisation:

Wernicke

Answer 15

Language is in the left Hemisphere Only,

Wernicke’s area is involved in speech comprehension.

Question 16

Evaluate Localisations function in the human brain:

Phineas Gage

Answer 16

A support for Localisation of function in the human brain is the curious case of Phineas Gage. Who while working on the railroad in 1848 an accident during work caused an explosion to hurl metre length pole through Gages left cheek, passing behind his left eye and exiting his skull from the top of his head taking a portion of most his Frontal Lobe. Incredibly Gage survived but the damage to his brain left a mark on his personality. By all accounts he had turned from someone who was calm and reserved to someone who was quick tempered, rude and no longer Gage. This case study suggested that the Frontal Lobe may be responsible for regulating mood and personality. This shows support as the localisation of personality is found in the Frontal Lobe.

Question 17

Evaluate Localisations function in the human brain:

Lashley and Rat Study

Answer 17

However, research to contradict this is a study by Lashley who suggests that higher cognitive functions such as the processes involved in learning are not localised but distributed in a more holistic way in the brain Lashley removed areas of cortex between 10 and 50% in rats that were learning a maze. No area was proven more important than any other area in terms of the rat’s ability to learn the maze. The process of learning appeared to require every part of the cortex rather than being confined to particular area. This seems to suggest that learning is too complex to be localised and requires the involvement of the whole of the brain. This however cannot be generalised to human brains as Humans and Rats are significantly different. This decreases the validity of the research.

Question 18

Evaluate Localisations function in the human brain:

Language

Answer 18

There is a wealth of evidence providing support for this idea thanks to technological advances with brain scans. An example was as study to show how the Wernicke’s area was active during a listening task and Brocas area was active during a reading ask, suggesting that these areas of the brain have different functions. Similarly a study of Long Term Memory revealed that semantic and episodic memories reside in different parts of the prefrontal cortex. This provides scientific and physical evidence of localisation

Question 19

Explain Plasticity

Answer 19

Brain plasticity refers to changes in the neural pathways and synapses which occurs as a result of changes in behaviour, environment and neural processes. Therefore, as a result of learning of brain injury the structure and function of the brain can change. Thus the brain is constantly changing throughout life.

Question 20

Explain Neural Unmasking

Answer 20

Neural Unmasking suggests when surrounding brain cells are damaged, the rate of input to dormant synapses increases. “Unmasking” the dormant synapses can open connections to previously inactive region of the brain, which over time leads to the development of new structures.

Question 21

Explain Stem Cells

Answer 21

Stem Cells can directly replace dead or dying cells. Alternatively, the stem cells secrete growth factors that somehow ‘rescue’ the injured cells. A third suggestion is that the transplanted stem cells form a neural network linking an uninjured brain area with the damaged region

Question 22

Evaluate evidence for plasticity and functional recovery after trauma:

Taxi Drivers

Answer 22

Support for this is a research from human studies on London taxi drivers to discover whether changes in the brain could be detected as a result of their expensive experience of spatial navigation. Using an MRI scanner, the researcher calculated the amount of grey matter in the brains of taxi drivers and a set of control participants. The posterior hippocampi of taxi drivers were significantly larger relative to those of control participants and posterior hippocampal volume was positively correlated with the amount of time they had spent as a taxi driver.

Question 23

Evaluate evidence for plasticity and functional recovery after trauma:

Plasticity and Functional Recovery of the brain

Answer 23

There are practical applications for plasticity and functional recovery of the brain. Illness or injury to the brain, spontaneous recovery tends to slow down after a number of weeks so forms of physical therapy may be required to maintain improvements in functioning. Techniques may include movement therapy and electrical stimulation of the brain to counter the defects in motor and or cognitive functioning that may be experienced. This shows that although the brain may have the capacity to ‘fix itself’ to a point, this process requires further intervention to be completed successfully.

Question 24

Evaluate evidence for plasticity and functional recovery after trauma:

Plasticity Tends To Reduce With Age

Answer 24

However it is also found that functional plasticity tends to reduce with age. The brain has a greater propensity for reorganisation in childhood as it is constantly adapting to new experiences and learning. It was found that children have a much greater capacity for neural reorganisation than adults, as evidenced by the extended practice adults need in order to produce functional changes following brain injury.