The Brain

Laterilisation

Each hemisphere of the brain has different jobs or roles

Sperry (1968) - procedure task 6

Patients performed block design tests - a type of spatial task (this was described as 'work in progress').

Sperry (1968) - results task 3

Patients were able to pick a wristwatch with their left hand. On another test they connected a 'piece of silverware' with a fork. This showed the limited language processing ability in the right hemisphere.

Sperry (1968) - results task 4

Patients' left hands could point to the correct answer. This demonstrated that the right hemisphere was involved in basic calculations

Sperry (1968) - procedure task 1

Sperry asked patients to fix their eye gaze on a particular spot and then projected words or pictures for 1/10th of a second (too fast for eye movements). This way he could be sure that the information only entered either the left or right hemisphere. The patient then had to feel for a particular object (hidden amongst others) behind a screen to identify what they had apparently seen with their eyes.

Sperry (1968) - results task 1

Sperry projected the words 'KEY' (left) and 'CASE' (right) and asked patients to identify the object they saw on each side. The patients could say 'case' and write it as normal, but reported not seeing anything to the left side. However, if asked to select the item they saw to the left with their left hand, they could choose the key correctly from either the items behind the screen or from an array of images. This indicated that the left visual field was being processed by the right hemisphere and the left hand by the right hemisphere, and vice versa

Sperry (1968) - procedure task 3

Sperry showed a picture of a wall clock to the patient's right hemisphere (Sperry called this the 'minor hemisphere') and asked them to pick the object closest to what they had seen with their left hand.

Sperry (1968) - evaluation : strengths

- Sperry gathered a lot of information, which improves the reliability of the study - The procedure was kept the same for each participant, keeping it standardised and more reliable - The study tells us a lot about the lateralisation of the brain

Sperry (1968) - conclusion

- The left hemisphere was the primary hemisphere for the processing of language (although Sperry showed limited language processing in the right too). - The right hemisphere was able to read words (which enabled the patients to recognise objects), make mental associations, process emotional reactions and solve simple arithmetic, and was better than the left hemisphere at spatial skills.

Evaluating gender differences in brain laterlisation : weaknesses

- The sex differences are not always apparent in the research = e.g. Rilea et al (2005) males did not always do better than females on spatial tasks - Some research has show no evidence for differences in brain lateralisation = Sommer et al (2004) found no strong evidence that females used both hemispheres in language tasks

Evaluating gender differences in brain laterlisation : strengths

- a lot scientific research conducted on differences in males and females = this allows research to be highly controlled, reliable using lab experiements - There is a lot of evidence to support sex differences in brain lateralisation = e.g. Harasty et al (1997) suggested parts of the brain responsible for language are bigger in females than in males.

Gender differences in Lateralisation

- females have a thicker corpus callosum - Females tend to use both sides of their brains for tasks - Males tend to show dominance for one hemisphere rather than an equal spread - This means males are more affected by brain damage to one side of their brain, whereas women are less affected by the same brain damage.

Sperry (1968) - procedure task 4

A sum was shown to the right hemisphere and patients were asked to use their left hand to point to what they thought was the correct answer to the sum.

Cerebellum

The cerebellum is a large hindbrain structure located below the occipital lobe. It contributes to the control of movement and is important for balance and coordination.

Frontal Lobe

The frontal lobe is located at the front of the brain and contains the primary motor cortex and the pre-frontal cortex. The frontal lobe is mainly involved in planning of movements, recent memory, and some aspects of emotion such as aggression. It is said to be crucial for planning and controlling thoughts and behaviour.

Occipital Lobe

The occipital lobe is located at the back of the brain and is the main target for visual information.

Damasio et al (1994) - conclusion

Ventromedial region of the frontal lobe responsible for sensible decisions

Damasio et al (1994) - aim

to investigate the brain damage to Phineas Gage using his skull, in order to determine functions of the frontal lobe

Sperry (1968) - procedure task 5

A picture of a nude was presented to the right hemisphere to see what the reaction would be.

Sperry (1968) - procedure task 2

In another test, Sperry asked patients to pick an item from a bag and name the object (without seeing it).

Corpus callosum

layer of fibres joining the hemispheres of the brain together

Brochas area

production of speech

Damasio et al (1994) - results

- Damage to both the LEFT and RIGHT hemisphere. - Extreme damage to the frontal lobe - Damage to WHITE MATTER (neurons pass their message along) - Damage was worse in the middle of each hemisphere (ventro medial region)

Sperry (1968) - evaluation : weaknesses

- It is hard to generalise from the study because the sample size is small and so specific - We can't say that split brains represent normal brains - The study was a lab experiment that lacked ecological validity - The task lacked validity - our visual fields normally work together, so we would not have these difficulties in real life

Synaptic Transmission

1. An electrical impulse is triggered inside the cell body of a neuron 2. A small impulse is passed along axon towards the end of the nerve 3. It arrives at the terminal buttonswhich are filled with small sacs called vesicles 4. These contain neurotransmitters (a chemical) 5. When the impulse reaches here, the vesicles release their chemical into the synaptic gap 6. These chemicals are then grabbed by the receptors on the next nerve cell, which continues the process to pass the message on.

Damasio et al (1994) - evaluation

1. It is hard to generalise from the study because the brain damage is so unique to Gage. 2. The reports of the damage are over 150 years old, meaning they may not be reliable. 3. Damasio et al were able to use modern day technology making the study quite scientific. 4. The use of a computer model is more reliable than the reports from 1848. 5. We can now make predictions about damage to the frontal lobes. 6. We can now treat people who have similar brain damage based on what happened to Gage. 7. The study is based on a real life case of brain damage so is valid.

Asymmetrical function

Both sides of the brain are not a mirror image of each other

Sperry (1968) - results task 2

If patients used their right hand they could name the object with ease. If they used their left hand they were unable to name it, but were able to retrieve it from a grab bag (provided that the left hand was used).

Parietal Lobe

The parietal lobe is located at the top of the brain between the frontal lobe and occipital lobe. It is responsible for bodily sensations and monitors all the information about eye, head and body positions before passing it on to the brain areas that control movement.

Sperry (1968) - results task 5

The picture of a nude would produce blushing or giggling, with no report verbally of having seen the image. This demonstrated that the right hemisphere was involved in emotional processing

Sperry (1968) - results task 6

The right hemisphere was judged to be superior to the left hemisphere in tasks involving drawing spatial relationships and performing block design tests.

Temporal Lobe

The temporal lobe is the side portion of each hemisphere and is located near the temples. It is the primary target for auditory information, so is essential for understanding spoken language. It is involved in advanced visual processing and plays a part in emotional and motivational behaviours.

Sperry (1968) - aim

To find out the cognitive functions that are linked to each hemisphere in the brain.