BIOPSYCHOLOGY A2

BIOPSYCHOLOGY A2

1. Ways of studying the brain

   • Techniques for investigating the brain are often used for medical purposes in the diagnosis of illness//The purpose of scanning in psychological research is often to investigate localisation
     • FMRI: detects changes in the blood oxygenation and flow that occurs due to specific neural activity in specific brain areas. The FMRI produces a 3D image showing which parts of the brain are active and therefore are involved in mental processes.//// HAEMODYNAMIC RESPONSE: when a brain area is active it consumes more oxygen and blood flow is directed to that area
       • + The FMRI is non invasive compared to techniques such as the PET scan as the FMRI does not rely on radiation and is safer. Also, it produces images with high spatial resolution showing detail by the mm so FMRI's can produce detailed pics of how brain activity is localised
       • - The FMRI is expensive compared to other techniques and can only produce an image if the patient is still. Also, it has poor temporal resolution because of a 5 second lag between initial neural activity and image. This means that may not truly represent moment-to-moment brain activity
       • EEG: measures electrical in the brain via electrodes using a skull cap. The sacn recording represents the brainwave patterns generated from millions of neurons which shows overall brain activity. EEG's are used as diagnostic tools eg. using arrhythmic patterns of brain activitymay indicate abnormalities such as epilepsy, tumours or sleep dicorders.
         • + A strength of EEG is that it is invaluable in diagnosing conditions such as epilepsy and has also contributed to our understanding of sleep stages. Also, it has high temporal resolution and can detect brain activity at the resolution of a millisecond
         • - A limitation is info is received from many thousands of neurons as EEg's produce a generalised siganal from thousands of neurons. Another limitation is that it's difficult to know the exact source of neural activity. EEG's can't distinguish the activity of diff, but adjacent neurons.
         • ERP's are what is left when all extraneous brain activity from an EEG recording is filtered out. Done using a statistical technique, leaving only those responses that relate to the presentation to a specific stimulus or performance of a specific task. ERP's are brainwaves that are triggered by certain events and research has revealed may diff forms of ERP and how these are linked to COGNITIVE processes eg perception/attention
           • + A ERP is a very specific measurement of neural processes and like EEG's also have v.good temporal resolution.
           • - it lackes standardisation in the methodolgy between studies which makes it difficut to confirm findings in studies involving ERP's. Another limitaion is that any background noise and extraneous material must be eliminated completely which isn't always easy to achieve.
           • POST-MORTEM: a technique involving the analysis of a persons brain following their death. areas of the brain are examined to determine the likely cause of a deficit or disorder that person suffered b4. this may also include comparison with a neurotypical brain in order to compare the diff
             • - Causation may be an issue as observed damage in the brain may not be linked to recorded disorders but trauma the person underwent in RL. Also, there's ethical issues because did the dead person consent beforehand? patients may not be able to eg HM or TAN
             • + PM's provide foundations for understanding the brain. Broca and Werenicke both relied on this method. PM's also improve medical knowledge and can generate hypothesis for further study

2. Biological Rhythms: Infradian & Ultradian

   • The menstrual cycle is an example of an Infradian rhythm and lasts around 28 (less than 1 cycle in 24hrs) Rising levels of OESTROGEN cause the ovary to develop and release an egg (ovulation) then PROGESTORONE helps the womb lining to thicken. If pregnancy does not occur the egg is absorbed and lining is removed (menstrual flow)
     • Exogenous zeitgebers may synchronise menstrual cycles: 2 researchers studies 29 women with irregular periods. PHEROMONES were taken via a cotton pad under their armpits throughout the 28 days. The pads were hygienically cleaned then placed on the lips of other pps. 68% experienced changes to their cycle which was bought closer to their 'odour donor'
       • E: + Research on the menstrual cycle shows its evolutionary value. It places the possibility that ancestor females may have menstruated together-got pregnant together so offspring cared for collectively. One researcher disagrees- so may females with similar cycle = all competitive and want the best quality male - so low potential for strong offspring
     • SAD - Another infradian rhythm. Seasonal Affective disorder is a depressive disorder (low mood etc) that is seasonal. The symptoms are triggered during winter months when daylight hours are shorter. SAD=a Circannual (yearly) cycle
       • During the night: *Pineal gland secretes melatonin till dawn (when it's light) *During winter, the lack of light means that secretion carries on. *this affects SEARTONIN production too (low S=depressive)
         • E:+ SAD has practical application because an effective therapy called phototherapy was introduced- a light box that stimulates a strong light in the morning and evening to try and reset melatonin levels. relieved 60% of sufferers . BUUUUUT one researcher used a placebo and found 30% were 'relieved' so casts doubt on whether therapy actually works
     • Ultradian rhythms: The sleep stages: The sleep patterns occur in 90 minute cycles (more than 1 in 24 hrs). Divided into 5 stages each with a diff brainwave activity (monitored by an EEG)
       • 1/2) LIGHT SLEEP: person can be easily woken , brainwaves become more slower and more rhythmic (ALPHA WAVES). slows further as sleep deepens (BETA W)
         • 3/4) deep sleep, cannot wake person up. DELTA WAVES- which are still slower but greater amlitude
           • 5) REM (rapid eye movement) occurs. Fast, jerky action of the eyes- body paralysed but brain activity speeds up
         • E: + There is evidence which supports qualitatively diff stages of sleep. A study by 2 researchers monitored sleep patterns of 9 pps. found evidence for stages of sleep especially REM. REM activity during sleep correlated with dreaming-brain activity varied according to how vivid the dreams were. pps woken during dream = accurate recall. suggests REM is an important concept of the ultradian sleep cycle

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4. Endogenous pacemakers and Exogenous Zeitgebers

   • The SUPERCHARISMATICNUCLEAS (SCN) is a tiny bundle of nerve cells in the hypothalamus which helps maintain circadian rhythms. Nerve fibres from the eye cross at the optic chaismon their way on to the visual cortex. The SCN lies just above the optic chiasm and recieves info about light from this structure.
     • 1 researcher destroyed the SCN connection in the brains of 30 chipmunks which were returned to their natural habitat for 80 days. The sleep/wake cycle was destroyed and many were eaten by predators
       • Pineal gland and melatonin are endogenous mechanisms: The SCN passes info on day length to the pineal gland which increases production of melatonin during the night. Melatonin: hormone that induces sleep - in hibited during periods of wakefulness and thought to be a causal factor in SAD
     • E: - One limitation of research into the SCN is that it may obscure other body clocks. Body clocks can be found in many organs and cells and are highly influenced by the SCN but can work independantly. 1 researcher changed ffeding pattern of rats - al;tered circadian rhythms of liver cells upto 12 hours but SCN overall unaffected. suggests other influences too
       • E: The use of exogenous zeitgebers may be overstated. CASE ST: one blind man from birth had a circadian rhythm of 24.9 hrs. His sleep/wake cycle could not allign with social cues so used sedatives at night/ stimulants in the morning to allign with the 24 hr world. Similiarly, ppl who live in Artic regions (sun not set during summer) show normal sleep patterns despite prolonged light exposure. so maybe exogenous zeitgebers not that important?
   • Without external cues the free running biological clock continues to tick in a cyclical pattern. Zeitgebers reset the sleep cycle: an interaction of internal and external factors// * ENTRAINMENT: reseting the biological clock
     • Light is a key exogenous zeitgeber: Light can reset the body's main endogenous pacemaker (SCN) and also has a indirect influence on key processes in the brain (eg cont hormone secretion)
       • 2 researchers woke 15 pps at various times and shone a light on the back of their knees. - produced a deviation in the sleep/wake cycle upto 3hrs. Light=powerful exogenous zeitgeber-detected by skin receptors so SCN is not completely reliant on eyes
         • E: - Methodological issues in exogenbous zeitgeber research as the SCN exp is yet to be replicated and is criticised as there may have been light exposure already to the pps eyes - MAJOR CONFOUNDING VARIABLE. Also, talkin g about just one zeitgeber (light) doesnt give indight into how the other E.zeitgebers affect us so suggests that some studies have ignored how E.zeitgebers interact - valid?