Biopsychology

(ways of studying brain / localisation of function / split-brain / plasticity / ult and inf rhythms)

Q4. Discuss what research has shown abt localisation of function (8)

AO1>
Some functions more localised than others e.g somatosensory and motor functions highly localised to particular areas of cortex
Others seem more widely distributed e.g language system (though some components may be localised e.g speech comprehension)
Systematic research from Wernicke and Broca onwards has demonstrated that in most people, lang centres are lateralised to left hemisphere
Wernicke’s area = Speech comprehension – damage leads to receptive or sensory aphasia
Broca’s area = Speech production - now thought to involve a wider network than just Broca’s area – damage leads to production (expressive) or motor aphasia
localisation can involve restricted areas of cortex e.g motor control or broader aspects e.g right hemisphere visuo-spatial functions

AO3>
:) Research Support for localisation of function (Aphasia studies)
these support localisation of brain functions as when a specific area is damaged, it results in specific loss of function.
-evidence for diff functions of Broca's + Wernicke's area in language production + understanding comes from discovery that damage results in diff types of aphasias

:( Contradictory Research for localisation of function
Bavelier conducted a study on silent reading and examined patterns of activation in the brain - found large variation in the patterns of activations b/w individuals e.g activation was seen in the left frontal, temporal, and occipital lobes.
- other studies found gender differences in size of brain areas associated with language
- shows it can vary from individual to individual
This goes against localisation of function as it suggests many diff areas are involved in function of reading --> individual differences as there are diff patterns of activation across diff individuals.

:( Biologically reductionist - tries to reduce very complex human behaviour + Cognitive processes to one specific brain region
critics suggest that a more thorough understanding of the brain is required to truly understand complex cog. processes like language
More research should be conducted in order to enhance and improve our understanding of localisation of function.

Discuss research into hemispheric lateralisation and split-brain (8)

AO1>
Lateralisation refers to the idea that the 2 halves of the brain are not identical
Some processes are specialised to either the left or right hemisphere
i.e language is mainly located in the left hemisphere. The corpus callosum allows the 2 hemispheres to communicate with each other (bundle of nerve fibres that allows info from 1 hemisphere to be sent to the other)
Left hemisphere also controls the muscles of the right side of the body therefore, when brain damage leads to speech problems combined with paralysis of body muscles, it is usually right sided. Research into split-brain patients (severed corpus callosum) is useful in researching hemispheric lateralisation (i.e language in LH)

AO3>
:) Research Support for hemisphere lateralisation (Sperry)
Provided us a unique way of testing the functions of each hemisphere and led to a wide body of research which helped our understanding of lateralisation.
concluded that language is geared to our left hemisphere and face recognition and spatial knowledge is in the right. This is a strength as it provides us the evidence to show there are clearly lateralised brain functions. This led Sperry to being awarded a Nobel prize for his contribution to research (increased credibility of psych)

:) Split brain research used a well controlled and scientific methodology, involving a standardised procedure that allowed Sperry to vary different aspects each time whilst ensuring only 1 hemisphere was receiving info at one time
For example - use of fixation points and the image or word being flashed up for only a fraction of a second ensured only 1 hemisphere was receiving info, allowing Sperry to vary the aspects of basic procedure to investigate hemispheric lateralisation in a well controlled way. However, the disconnection b/w the 2 hemispheres were greater in some patients than others. some patients have also been in drug therapy for their epilepsy for many years and for a longer amount of time than other patients (difficult to generalise the findings to the whole population and make comparisons even within the patients as they differed in the extent to which their corpus callosum has been severed). Furthermore, the sample size was small, and the control group had no history of epileptic seizures, which not only made the comparisons even harder, but also makes it harder to generalise the findings and draw suitable conclusions on how functions are lateralised to each hemisphere.

Q7. Discuss the consequences of disrupting biological rhythms (e.g. shift work, jet lag). (16)

AO1>
Biological rhythms such as the sleep wake cycle are regulated by Endogenous pacemakers and Exogenous zeitgebers.
EPs = internal mechanisms that govern biological rhythms e.g circadian s/w cycle
EZs = external cues from env e.g light lvls / social cues / noise lvls
Although EPs act like internal body clocks, they can be affected by external env e.g changes in light lvls e.g when day turns to dusk and light is required to reset sleep-wake cycle every 24 hrs.

The Superchiasmatic Nucleus (SCN is the main EP, closely associated w pineal gland. Known as the master clock, Located in hypothalamus)
SCN sends signals to pineal gland, increasing production of melatonin secretion at night, helping to induce sleep
- Eye receives info abt light lvls from optic nerve (even when asleep) this info sets the circadian rhythms so it’s synchronised w outside world e.g day and night
- Info sent to SCN -> SCN alerts pineal gland to secrete melatonin
- Melatonin lvls increase at night, helping to induce sleep -> Once it becomes light, melatonin production is inhibited

Jet lag and work (night shifts) can disrupt the sleep-wake cycle. Travel can result in phase advance (travelling from west to east), making it difficult to wake up due to being in a circadian trough, or phase delay (travel from east to west) where a person would sleep later than usual. This can result in jet lag which results in desynchronisation due to your internal body clock not being synchronised with the external cues. To overcome it, you should be exposed to bright light before a flight and on arrival, follow the EZ of the new tie zone i.e day time and social cues - eat at meal times even if not hungry.

Shift work disrupts bio. rhythms as working at night and sleeping during the day is the reverse of natural rhythms and out of line with exogenous zeitgebers. Night workers experience decreased alertness during shifts bc they’re working during a circadian trough (12 - 4 am) where cortisol and core body temp is at their lowest, which can pose a risk to job performance and individual well-being. Working during the night can also cause sleep problems bc it’s difficult to sleep during the day due to interruptions (such as light and noise). This poor sleep hygiene can further make it difficult to stay awake during night shifts.

Shift work can also have adverse effects on health (link b/w shift work and organ disease). Demonstrated by Krutsson et al, where they found that ps who worked shifts for more than 15 yrs were 3x more likely to develop heart disease than non-shift workers. Furthermore, Martino et al linked shift work to kidney disease (may be due to the effects of the desynchronisation of rhythms, or sleep disruption as growth and repair hormones aren’t functioning effectively)

AO3>
:) Research support for EZ (Burgess [2003])
P: Jet lag study - Strength - application to avoiding jet lag
E: Exposure to bright light prior to east-west flight decreased time needed to readjust to local time on arrival
E: Ps exposed to continuous bright light shifted their circadian rhythm by 2.1 hrs over the course of the study, thus, were brought closer to the local time cond. Such that they wouldn’t experience jet lag.
L: This demonstrates power of EZs and utility in our everyday experiences. This research is particularly important for those who may fly frequently (businessmen)

:( Social disruptions
Further effects of shift work is that shift workers experience social disruptions as well as disruptions to biological rhythms
This is because it is difficult to meet friends and spend time with family. Solomon (1994) found that divorce rates among all night shift workers were as high as 60%
This suggests that shift work has negative social impacts, which may cause stress and further the decline of health (Rahe et al, 1970)

:( Individual differences
Research has indicated that individual differences may have a mediating influence between shift work and its effects
Reinberg et al (1984) found that people who gave up shift work because they couldn’t cope tended to have rhythms that changed a lot while on shift, whereas the “happy shift workers” had unchanging rhythmsThis suggests that the effects of shift work vary for every individual, and has implications for employers and workers; people that experience changing circadian rhythms should be targeted and have access to ways that will reduce the effects

:) Understanding circadian rhythms and the effects of desynchronisation has had practical app. to shift work
Karlsson, Knutsson and Lindahl (2001) found shift work was associated w obesity, high triglycerides and low conc. of HDL cholesterol, which may demonstrate link b/w desynchronisation of circadian slee-wake cycles in shift workers and the consequent disruptions in the biological control of metabolism (and therefore core body temp). Therefore, research into sleep / wake cycles can help the economy in terms of how to better manage worker productivity e.g companies who employ shift-workers making the effort to revise their policies in order to reduce days taken off sick.

:) Role of melatonin in inducing sleep
From research in this area, melatonin has been suggested as a “miracle cure” for shift lag and jet lag as it induces sleep
A review of 10 studies by Herxheimer and Petrie (2001) reviewed 10 studies and found that when melatonin was taken just before bedtime, it was remarkably effective. However, if it was taken at the wrong time of day it could delay adaptation
This suggests that melatonin is an effective treatment that enables high quality sleep only if taken at appropriate times (just before sleep)

Q2. Josie is twelve. Last year she was involved in a serious road accident and suffered head injuries that caused problems with speech and understanding language. Now, a year later, Josie has recovered most of her language abilities.
Using your knowledge of plasticity and functional recovery of the brain after trauma, explain Josie’s recovery. (4)

Trauma more likely when brain still developing
Josie = young
Neural organisation (function transferred to undamaged areas)
Neural regeneration (new neuron growth) to compensate for dmged areas
Plasticity allows brain to cope better w indirect effects of brain dmg

Q3. Lotta’s grandmother suffered a stroke to the left hemisphere, damaging Broca’s area and the motor cortex.
(a) Using your knowledge of the functions of Broca’s area and the motor cortex, describe the problems that Lotta’s grandmother is likely to experience. (4)

Dmg to broca’s area = likely to suffer from language / speech problems (Broca’s aphasia)
Will affect her language production (but not her understanding)
Only be able to talk in short meaningful sentences which take great effort
Speech lacks fluency / difficulty w certain words which help sentences function (e.g. ‘it’ and ‘the’)
Dmg to motor cortex - likely to suffer from loss of muscle function / paralysis
Motor impairments on right side of body

Q3. Lotta’s grandmother suffered a stroke to the left hemisphere, damaging Broca’s area and the motor cortex.
(b) Lotta worries that because of her grandmother’s age she will not be able to make any recovery. Using your knowledge of plasticity and functional recovery of the brain after trauma, explain why Lotta might be wrong. (4)

Might still be capable of neural reorganisation (transfer of functions to undmged areas) / plasticity
Although she’s older her brain might still be able to form new connections b/w neurons + neuronal loss may be compensated for by regeneration (growth of new neurons / connections for dmged areas)
Plasticity allows brain to cope better w ‘indirect’ effects of brain damage resulting from inadequate blood supply following a stroke
Physiotherapy for increased brain stimulation of opp hemisphere

Q1. Outline one or more examples of ultradian rhythms (4)

Cycles lasting less than 24 hrs e.g alternation between REM and NREM sleep during the night (5 sleep stages)
No. of REM eps per night / link w stage 2 NREM / characteristics of each sleep type
NREM = 75-80% of time spent in sleep
REM = more complex dreams

Q1. Outline one or more examples of infradian rhythms (4)

Have a period of more than 1 day but less than 1 year e.g menstrual cycle (averages at 28 days) regulated by hormones (controlled by pituitary gland)
oestrogen - promotes ovulation, lvls peak halfway through cycle
when highest, ovulation occurs
progesterone - prepares uterus lining for possible egg implantation
lvls increase post=ovulation to prepare for possible pregnancy (also influenced by EZ e.g stress / diet / food / exercise)