Here are some example answers to the written Paper 2 questions on Biopsychology in the 2019 AQA exams.
The endocrine system is a network of glands across the body that secrete chemical messengers called hormones into the blood stream. Each hormone is secreted by a particular gland in the endocrine system and produces specialised effect. One hormone is called melatonin. This is produced by the pineal gland in the brain. The effect of melatonin is that it helps regulate the sleep wake cycle.
Hemispheric lateralisation is the theory that the two halves of the cortex of the brain are functionally different and that each hemisphere has functional specialisations. The two hemispheres themselves are connected through a set of nerve fibres known as the corpus callosum, these fibres facilitate the communication between the left and right hemispheres of the brain. To research whether the left and right hemispheres of the brain have functional specialisms is difficult as the corpus callosum allows communication between the two hemispheres. This has led researchers to seek out patients whose corpus callosums, whether through, injury, genetics or surgery are not in-tact. For example, the research from Sperry’s select case of epileptic patients who had their corpus callosum removed to reduce seizures. Sperry’s research was able to demonstrate the functional speciality of the left and right hemispheres through the use of specialist equipment called a tachistoscope. Sperry presented words to either the left of right visual field. Owed to the contralateral configuration of the brain the words presented to the LVF would be processed in the right hemisphere and the words form the RVF in the left hemisphere. Sperry’s patients were able to verbally state words appearing to their LVF but not their right. This aligns with Broca’s assertion that the left hemisphere is responsible for language and speech.
It is clear from Kieran’s comments about the left brain being responsible for certain tasks that he is referring to hemispheric lateralisation, that the brain is lateralised and certain sides of the cortex are individually responsible for certain function, such as Kieran says, the left hemisphere for speech and language where Broca and Wernicke’s area are located. Sam on the other hand is referring to how the two parts of the cortex, the left and right hemisphere are able to communicate with each other through a system of fibres known as the corpus callosum, when he refers to the whole brain working together.
Although the work of Sperry and Broca supports the theory of hemispheric lateralisation, there is research that contradicts these findings. Interestingly the case study of Kim Peek, who was born without a corpus callosum demonstrated the Peek was able to read out-loud from a book from the right and left pages at the same time, if language was, like Broca and Sperry had argued, lateralised to the left hemisphere Peek would have only been able to read aloud the words from the right page. This criticism is further reinforced by Turn (2002) who discovered a patient who suffered damage to the left hemisphere, but developed the capacity to speak from the right hemisphere, eventually leading to the ability to speak about information presented to either side of the brain. This points to the fact that through a process of functionally recovery, lateralised functions may appear on opposing sides after injury.
Another factor to consider in respect to hemispheric lateralisation is the degree to which the brain is lateralised. There is research by Shaywitz 1995 for example to support the idea that in males the brain may be more lateralised for language than in females. This is further supported by Baron Cohen 2005 who asserted that these gender differences in lateralisation may also contribute to the incidence of disorders such as ASD. Both of these pieces of research serve to demonstrate that hemispheric lateralisation is much more complex that Sperry and Broca’s research indicates.
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