Hemispheric Lateralisation & Split brain research BP

Question 1

hemispheric lateralisation

Answer 1

the idea that the two halves (hemispheres) of the brain are functionally different and that certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other, as in the example of language

Question 2

split-brain research

Answer 2

a series of studies which began in the 1960’s involving people with epilepsy who had experienced a surgical separation of the hemispheres of their brain to reduce the severity of t

Question 3

contralateral wiring

Answer 3

right hemisphere controls movement on left side and vise versa

Question 4

Localisation

Answer 4

Some functions like vision and language are localised to specific areas of the brain.

Question 5

lateralisation

Answer 5

There are two sides of the brain called hemispheres (lateralised).

Question 6

language

Answer 6

• Mostly left hemisphere
• Broca’s area (left frontal lobe)
• Wernicke’s area (left temporal lobe)
• Language is lateralised
• Right hemisphere contributes emotional context to what is being said

Question 7

vision

Answer 7

• Not lateralised
• Contralateral and ipsilateral (opposite and same-sided)
• Both eyes receive light from both visual fields
• Left visual field of both eyes is connected to the right hemisphere
• Right visual field of both eyes is connected to the left hemisphere
• This aids depth perception and comparison of different perspectives

Question 8

non-lateralised functions:

Answer 8

• Vision, motor, somatosensory areas
• In motor area, brain is cross-wired (contralateral wiring)

Question 9

Sperry’s research:

Answer 9

Study how two separated hemispheres deal with speech, vision

Question 10

Sperry’s procedure

Answer 10

• 11 people who had split-brain operation were studied (image projected to participants right visual field and vice versa)
• In ‘normal’ brain, the corpus callosum would immediately share information between both hemispheres (complete image of the world)
• However, on split-brain participants information cannot be conveyed from that hemisphere to the other

Question 11

sperry’s fidnings

Answer 11

When picture of object was shown to right visual field, participants could describe what could be seen

Could not be seen if on LVF - ‘nothing was there’
* Due to the relaying of messages fro, RH to LH, and isn’t possible in split-brain
* No verbal labels to objects
* But could select matching objects out of sight

Question 12

Sperry’s conclusion

Answer 12

Certain functions in the brain are lateralised

Question 13

Lateralisation in the connected brain

I:

strength

Answer 13

The two hemispheres process information differently

Fink et al used PET scans to see which areas were active during a visual processing task

Question 14

Lateralisation in the connected brain

D:

strength

Answer 14

When looking at the picture as a whole the RH was more active

LH for more active for finer details

Question 15

Lateralisation in the connected brain

E:

strength

Answer 15

For visual processing, hemispheric lateralisation is a feature of the connected brain and the split-brain

Question 16

One brain

I:

limitation

Answer 16

The theory that LH as analyser and RH as synthesiser may be incorrect and the research has lead to the erroneous pop-psychology notion that people are left or right brained

Question 17

One brain

D:

limitation

Answer 17

Nielsen et al analysed 1000 brain scans from people aged 7-29 and found evidence for lateralisation

But no evidence for a dominant side

Question 18

One brain

E:

limitation

Answer 18

The notion of right or left brained people is wrong

Question 19

Lateralisation versus plasticity

Answer 19

Lateralisation is adaptive as two tasks can be performed at the same time (supported by Rodgers et al, who found that lateralised chickens can find food and watch predators but other chickens can’t)

Neural plasticity is also adaptive as after damage to an area, some functions can be taken over by non-specialised areas (Holland et al)

Question 20

Split-brain research support

I:

strength

Answer 20

More recent split-brain research

Question 21

Split-brain research support

D:

strength

Answer 21

Gazzaniga showed that split-brain participants actually perform better than connected controls on certain tasks

Faster identifying the odd one out in an array of similar objects

Question 22

Split-brain research support

E:

strength

Answer 22

Left and right side differ in terms of functioning

Question 23

Generalisation issues of split brain research

I:

limitation

Answer 23

Limitation of Sperry’s research is that causal relationships are hard to establish

Question 24

Generalisation issues of split brain research

D:

limitation

Answer 24

• Split-brain ppts were compared to a neurotypical control group
• None of the ppts in control group had epilepsy
• This is major confounding variable

Question 25

Generalisation issues of split brain research

E:

limitation

Answer 25

Any differences might have been due to the epilepsy rather than the split-brain