Topic 5: Biopsychology Flashcards

Question

Testes

Answer 1

Main hormone released: Testosterone Effect: Responsible for the development of male sex characteristics during puberty, while also promoting muscle growth.

Answer 2

1) The **Amygdala** sends a 'distressed signal' to the hypothalamus. 2) The **hypothalamus** releases **CRH** into bloodstream. 3) The **pituitary gland** releases **ACTH** into the bloodstream, and from there to its target sites. 4) The **SNS** prepares the body for rapid action and sends a signal to the **adrenal medulla**. 5) The **adrenal medulla** releases **adrenaline** into the blood stream, causing psychological changes such as **increased heart rate and increased release of blood sugar**. 5) The **PNP** dampens down the stress response once the threat has passed, slowing down the hb and reducing release of blood sugar.

Answer 3

HPA Axis: 'H' = The **Hypothalamus** responds to threat and releases **CRH** into bloodstream. 'P' = The **pituitary gland** receive CRH, which stimulates the production and release of **ACTH**. 'A' = The **adrenal gland** is activated by the arrival of ACTH. This causes the **adrenal cortex** to release a stress related hormone e.g. cortisol, which results in some negative and some positive fight or flight responses e.g. quick energy bursts and lower pain sensitivity but impaired cognitive response and lowed immune response.

Answer 4

- Our reaction to danger is not limited to the fight or flight response: **Gray (1988)** suggests that the first response to danger is to avoid confrontation altogether, which is demonstrated by a **freeze response**. - The fight or flight response is typically a male response to danger and more recent research suggests that females adopt a **‘tend and befriend’** response in stressful/dangerous situations. According to **Taylor et al. (2000),** women are more likely to protect their offspring (tend) and form alliances with other women (befriend), rather than fight an adversary or flee. Potential gender bias? Is this because of society or biology? - Early research into the fight or flight response was typically conducted on males (androcentrism) and consequently, researchers assumed that the findings could be generalised to females. This highlights a **beta bias** within this area of psychology. - The fight or flight response is a **maladaptive response in modern-day life**. Modern day life rarely requires such an intense biological response, which if repeatedly activated can have a negative consequence on our health. E.g rise in blood pressure can damage blood vessels.

Answer 5

Refers to the belief that specific areas of the brain are associated with specific cognitive processes.

Answer 6

When the left hemisphere processes information from the right side of the body and vice versa.

Answer 7

Function: Verbal fluency / speech production. Enables speech to be fluent. Location: Frontal Lobe Hemisphere(s): Left Processes: Controls verbal fluency

Answer 8

Function: generation of voluntary motor movements. Location: Frontal Lobe Hemisphere(s): Both Processes: Controlls muscle movements on opposite sides of the body.

Answer 9

Fucntion: Senses (i.e. touch, pressure, pain, temperature) Location: Parietal Lobe Hemisphere(s): Both Processes: Processes input from sensory receptors in the body and on the skin that are sensitive to touch.

Answer 10

Function: Vision Location: Occipital Lobe Hemisphere(s): Both Processes: Recieves nerev impulses from the optic nerve and contains several different areas, which proccess different types of visual info (i.e.colour, shape or movement).

Answer 11

Function: Hearing Location: Temporal Lobe Hemisphere(s): Both Processes: Receives processed info from the cochlea which turns sound waves into nerve impulses. In the auditory cortex the sound is reorganised and may result in an appropriate response.

Answer 12

Function: Speech understanding/language comprehension. Enables speech to be meaningful. Location: Temporal Lobe Hemisphere(s): Left Processes: Important in the comprehension of language

Answer 13

wealth of case studies on patients with damage to Broca’s and Wernicke’s areas that have demonstrated their functions. For example, **Broca’s aphasia** is an impaired ability to produce language; in most cases, this is caused by brain damage in Broca’s area. **Wernicke’s aphasia** is an impairment of language perception, demonstrating the important role played by this brain region in the comprehension of language. - Wernicke found that patients with lesions to Wernicke’s area were still able to speak, but were unable to comprehend language (Wernickels aphasia). However, research by **Saygin et al**. (2003) found that some patients displayed symptoms of Wernicke’s aphasia without any damage to this area. This suggests that language comprehension is much more complex than originally thought. Further evidence has also been found which suggests some left-handed people process language in the right hemisphere. - **Paul Broca's** study: "Tan" was a patient with severe speech impairment, only able to say the word "tan" but could still comprehend speech. Post-mortem analysis: After Tan's death, Broca examined his brain and discovered a lesion in the left frontal lobe. This finding led Broca to conclude that this specific area of the brain is crucial for speech production, now recognized as Broca's area. contradictory evidence - **Dronkers et al**. (2007) conducted an MRI scan on Tan’s brain, to try to confirm Broca’s findings. Although there was a lesion found in Broca’s area, they also found evidence to suggest other areas may have contributed to the failure in speech production, suggesting that Broca’s area may not be the only region responsible for speech production and the deficits found in patients with Broca’s aphasia could be the result of damage to other neighbouring regions and thus localisation is oversimplified. - **Lashley** proposed the **equipotentiality theory**, which suggests that the basic motor and sensory functions are localised, but that higher mental functions are not. He claimed that intact areas of the cortex could take over responsibility for specific cognitive functions following brain injury, casting doubt on theories about the localisation of functions. Has received support from research into fucntional recovery. - Wernicke claimed that although the different areas of the brain are independent, they must interact with each other in order to function. **Dejerine** reported a man who lost his ability to read, following damage to the connection between the visual cortex and the Wernicke’s area. This suggests that interactions between different areas produce complex behaviours such as language. Therefore, damage to the connection between any two points can result in impairments that resemble damage to the localised brain region associated with that specific function. This reduces the credibility of the localisation theory. - **biologically reductionit** in nature and tries to reduce very complex human behaviours and cognitive processes to one specific brain region. - One such case study is that of **Phineas Gage**, who in 1848 while working on a rail line, experienced a drastic accident in which a piece of iron went through his skull, damaging his left frontal lobe. Although Gage survived this ordeal, he did experience a change in personality, such as loss of inhibition and anger. This change provided evidence to support the theory of localisation of brain function, as it was believed that the area the iron stake damaged was responsible for personality. - localisation fails to take into account individual differences. **Herasty** (1997) found that women have proportionally larger Broca’s and Wernicke’s areas than men, which can perhaps explain the greater ease of language use amongst women. This, however, suggests a level of **beta bias** in the theory: the differences between men and woman are ignored, and variations in the pattern of activation and the size of areas observed during various language activities are not considered.

Answer 14

Refers to the fact that some mental processes in the brain are mainly specialised to either the left or the right hemisphere. Left hemisphere: Dominant for language and speech, writing and rational thinking. Right hemispherre: Excels at visual motor-tasks, visuo-spatial, face-recognition, pictures, creativity. The two hemispheres are connected through nerve fibres called the corpus callosum, which facilitate interhemispheric communication: allowing the left and right hemispheres to ‘talk to’ one another

Answer 15

Research that studies individuals who have been subjected to the surgical seperation of the two hemispheres of the brain as a result of severing the corpus callosum. **Sperry and Gazzaniga** (1967) were the first to investigate hemispheric lateralisation with the use of split-brain patients. Aim: To examine the extent to which the two hemispheres are specialised for certain functions. Method: An image/word is projected to the patient’s left visual field (which is processed by the right hemisphere) or the right visual field (which is processed by the left hemisphere). When information is presented to one hemisphere in a split-brain patient, the information is not transferred to the other hemisphere (as the corpus callosum is cut). **Describe what you see task**: a picture was presented to either the left or right visual field and the participant had to simply describe what they saw. Pictures presented to the RVF (processed by left hemisphere): patient could describe what they saw. Picture presented to the LVF (processed by right hemisphere): The patient could not describe what was shown. Demonstrates the LH's superiority for language. **The tactile test**: an object was placed in the patient’s left or right hand and they had to either describe what they felt, or select a similar object from a series of alternate objects. - Objects placed in the right hand (processed by the left hemisphere): The patient could describe verbally what they felt. Or they could identify the test object by selecting a similar appropriate object, from a series of alternate objects - Objects placed in the left hand (processed by the right hemisphere): The patient could not describe what they felt. However, the left hand could identify a test object presented in the left hand (right hemisphere), by selecting a similar appropriate object, from a series of alternate objects. **drawing task**: participants were presented with a picture in either their left or right visual field, and they had to simply draw what they saw. - Pictured presented to the RVF (processed by left hemisphere): While the right-hand would attempt to draw a picture, the picture was never as clear as the left hand, demonstrating the superiority of the right hemisphere for visual motor tasks. - Picture presented to the LVF (processed by right hemisphere): The left-hand (controlled by the right hemisphere) would consistently draw clearer and better pictures than the right hand (even though all the participants were right-handed). This demonstrates the superiority of the right hemisphere when it comes to visual motor task. C: the left hemisphere is dominant in terms of speech and language. the right hemisphere is dominant in terms of visual-motor tasks.

Answer 16

- Splitt brain research: **Sperry**. Issues with generalisation as split-brain patients constitute such an unsual sample of ppl. Arguably, the history of epileptic seizures in Sperry's patients may have caused unique changes in the brain that may have influence his findings as the control were ppl with no history of epilepsy. Case-studies are mostly idiographic and involve small samples and unique circumstances. - New medication for epilepsy has replaced surgery meaning that split-brain research can no longer be replicated to test reliability. - It is assumed that the main advantage of brain lateralisation is that it increases neural processing capacity (the ability to perform multiple tasks simultaneously). **Rogers et al**. (2004) found that in a domestic chicken, brain lateralisation is associated with an enhanced ability to perform two tasks simultaneously (finding food and being vigilant for predators). Using only one hemisphere to engage in a task leaves the other hemisphere free to engage in other functions. This provides evidence for the advantages of brain lateralisation and demonstrates how it can enhance brain efficiency in cognitive tasks. o However, because this research was carried out on animals, it is impossible to conclude the same of humans. - **Lateralisation may change with age**. **Szaflarki et al.** (2006) found that language became more lateralised to the left hemisphere with increasing age in children and adolescents, but after the age of 25, lateralisation decreased with each decade of life. This raises questions about lateralisation, such as whether everyone has one hemisphere that is dominant over the other and whether this dominance changes with age. - Language may not be restricted to the left hemisphere. **Turk et al**. (2002) discovered a patient who suffered damage to the left hemisphere but developed the capacity to speak in the right hemisphere, eventually leading to the ability to speak about the information presented to either side of the brain. This suggests that perhaps lateralisation is not fixed and that the brain can adapt following damage to certain areas.

Answer 17

Refers to the brain's ability to modify it's own structure and function as a result of experience. It refers to the brain's ability to change and adapt connections or re-wire itself from new learning. Without this ability the brain would be unable to develop from infacny to adulthood or recover from brain injury. **Constant re-organisation** 1) Infor takes a set pathway through the brain, travelling from one neurone to the next via synapses. 2) When we are presented with new info new neural pathways begin to form. 3) Using a neural pathway strengthens it - a more a pathway is used, the stronger in becomes. 4) If a neural pathway is not used it becomes lost. **Axon sprouting** - The growth of new nerve endings that connect with other damaged nerve cells to form new neuronal pathways. **Synaptic pruning** - The brain deletes neural connections that are rarely used and strengthen those that are.

Answer 18

- Meditating Monks (**Davidson et al**): Studied the effects that compassion meditating had on the brain's ability to repond empathetically. Practicing monks compared to 16 aged matched controls, showed an increase in the brain circuits used to detect emotion. Measured through a FMRI and gamma waves. - Animal Studies (**Kempermann** et al): Found increased number of neural connections in the brains of rats housed in compex environments compared to rats housed in laboratory cages, particularly to the hippocampus. Evidence of the brain's ability to change as a result of experience. Practical applications as it highlights the importance of enriching environments (i.e. for young children who are developing). - **Maguire** studied the brains of London taxi drivers (who had to undergo intense training) using MRI scans. Found that London taxi drivers had considerably more grey matter in the hippocampus than controls, suggesting the brain can be physcially changed as a result of learning.

Answer 19

Refers to the recovery of abilities and mental processes that have been compromised as a result of brain injury or disease. After an injury/damage unaffected areas of the brain are often able to adapt and compensate for lost function. - **Spontaneous Recovery**: Occurs the first few weeks after trauma, a period of heightened levels of neural plasticity in the brain. Most neuro re-habilitaion stratergies target this period as plasticity slows down thereafter. - **Neuronal unmasking**: 'Dormant' synapses (which have not recieved enough input to be active) open connections to zcompensate for a nearby damaged area in the brain, allowing for a new connection in the brain to be activated, thus recovering any damage occuring in specific regions.

Answer 20

- **Age**: **The Kennard Principle** - The earlier in life brain damage is sustained, the better the chance of recovery. A child's brain will re-organise itself, putting common processing structures in places where they aren't normall found. However, an older person's brain seeks out stratergies for coping with loss of function (ignore the problem rather than change itself). - **Tajiri et al** animal study: Randomly assigned rats with traumatic brain injuries to one of two groups: one groups had stem cells transplanted into the affected area of the brain, and the other group had a solution with no stem cells. The brains of the stem-cell rats showed clear development of neuron-like cells in the area of injury. This demonstrates the ability of the brain to create new connections using neurons manufactured by stem cells. Important research as it may lead to potential treatments for brain injuries using stem cells, based on the idea of functional recovery. Animal study so extrapolation issues - human brain = more complex. - **Shneider et al** (2014) - **Cognitive Reserve**: Discovered that the more time brain injury patients had spent in education, the greater their chances of disability free recovery (DFR). **40%** of patients with more than 16 years of education achieved DFR, in comparison to 10% of patients will less than 12 years. Dementia has a higher rate of diagnosis in lower-and-mid socioeconomic areas, so school attendance is likely to be lower. - **Negative Plasticity**: may explain why addicition can't be cured, thinking strengthens the neural connections. Phantomb limb is an example of a negative neural adaption. - If our brains were completely plastic then recovery would always be possible and born learning difficulties would be overcome, which isn't the case. - **Practical Application: Constraint-induced movelemt therapy (CIMT)**: After a stroke patients might suffer from a loss of function on one side of the body. CIMT forces patients to relearn the use of their affected area by preventing the use of their non-affected side. CIMT demonstrates a high success rate.

Answer 21

A pattern of behaviour that occus or recurs approximately every 24 hours, and which is set and reset by environmental light levels. Examples: sleep-wake cycle, core body temperature, Hormone Production.

Answer 22

Distinct patterns of chnages in activity of the body that conform to regular and cyclical time periods

Answer 23

- Levels of **melatonin** rise and fall. - our master circadian pacemaker, **the suprachiasmatic nucleus** (SCN) found in the hypothalamus, must be reset so that we can keep in time with the outside world. Light sensitive cell in our eyes communicate with the SCN, which co-ordinates the carcadian-rhythm. - The SCN is stimulated by darkness and sends signals to the **pineal gland**, which releases **melatonin**, causing us to fall asleep. The opposite effect occurs in light, the SCN is inhibited from telling the pineal gland to release melatonin and we remain awake.

Answer 24

Temp rises in the morning (lowest at around 4-6am) from 36dc to 38dc (highest about 6pm). Starts to drop again when ready for sleep.

Answer 25

Internally helps us to regulate our sleep/wake cycle (i.e. SCN)

Answer 26

Externally help us to regulate our sleep/wake cycles (i.e light and time).

Answer 27

Aim and background: To investigate the effects of the absence of external zeitgebers (environmental cues) on the human circadian rhythm, particularly the sleep-wake cycle. NASA was interested in the research, as they wanted to find out what it would be like for astronauts in space who would also be living without daylight, in isolation. Stayed in a dark cave for extended periods of time. 1962 - first underground stay - 61 days (2 months) --> he resurfaced 17th Sept believing it to be 20th Aug. As he believed the date was a month earlier than it was after returning from an underground stay without clocks or light, this suggests that the lack of external cues increased his sleep-wake cycle to be around 26 hours. decade later - 2nd occasion - 6 months in a cave in Texas in both cases - his natural circadian rhythm settled down to 25 hours but sometimes this would change dramatically to as much as 48 hours, though he did fall asleep and wake up on a regular schedule. The cave was in complete darkness, lit by artificial lighting only, which was controlled by the researchers. There was no natural light and no way of telling the time (no clocks). When he was tired and believed it was “night time” he would phone the researchers to ask them to turn the lights off. Every time Siffre woke up from his sleep, he would phone the researchers to ask them to turn the lights on. Siffre conducted several tests on himself during the time in the cave, such as: Blood pressure, Memory tests, Cycling 3 miles on an exercise bike He had to clean the cave daily, as the dust would have been a big risk to his health. Siffre also became depressed due the loneliness. His memory was negatively impacted, as was his eyesight. 1999 - 3rd underground stay - when he was 60 years old, interested in the effects of ageing on his circadian rhythm found that his body clock ticked more slowly than when he was a young man - sometimes it stretched his circadian rhythms to 48 hours Conclusions: circadian rhythms persist despite isolation from natural light - demonstrates the existence of an 'endogenous clock' also shows that external cues are important - clock was not accurate, it varied from day to day Exogenous Zeitgebers are important for several reasons, and their absence can impact memory and mental health. Without external cues, the sleep-wake cycle (which is usually circadian) can sometimes double in length. Evaluations: - The study only involved one person (idiographic), so the findings aren't generalizable. - The cave isn't where humans would normally sleep, so the study lacks ecological validity. - Had access to artificial light, challenges internal validity. - Study was completed over a long period of time- 6 months spent in the cave - findings are less likely to have been because of chance. - (+) The procedure was somewhat standardised – the same equipment could be provided to another individual, and the same controlled set-up with lighting controlled by a researcher. - (+) The results were useful to astronauts – the study showed that isolation was not good for mental health and that astronauts would need companionship.

Answer 28

- Studied a group of PPs confined in a WW2 bunker for 4 weeks. The PPs were deprived of light and other possible zeitgebers. - F: All but one of the PPd (who's carcadian rhythm extended to 29hrs) sleep/wake cycles remained at 24-25hrs. - C: Suggests that the 'natural' sleep/wake cycle may be slightly longer the 24hrs but that it is entrained by exogenous zeitgebers associated with a 24hr day (i.e. daylight hrs, typical meal-times etc). Suggests that we are more internally regulated.

Answer 29

- Studies a group of 12 PPs who agrees to live in a dark cave for 3 weeks. - The cave contained a single clock. However, the time was altered to produce a 22 hr day. - They generally struggled to cope with adjusting to the new cycle. Suggesting that PPs retained their natural circadian rhythms. - 3 weeks doesn't investiagte long term.

Answer 30

Applications: - **chronotherapuetics**(the study of how timing affects drug treatments) : Circadian rhythms co-ordinate things like heart-rate, digestion, hormones, which have an effect on pharmacokinetics. Research into circadian rhythms have shown peak times during the night or day when drugs are likely to be most effective, leading to the development of guidlines for the timing of drug dosing. I.e. risk of heart attack is greatest during early hours of the morning after waking. - **Shift Work**: Research has provided better understanding of the adverse consequences of desynchronisation. Night workers engaged in shift work experience a period of reduced concentration around 6am (circadian trough) - accidents are more likely at this time. Research suggests a relationship between shift work and poor health (shift workers 3X more likely to develop heart disease - **Knutsson** 2003). - Could explain jet lag. - **Education**; According to neuroscientists, teenagers circadian rhythms typically begin 2hrs before adults. Pilot study by **Dr Paul Kelley** put the start of the school day back by to 10am over a 2yr period at Monkseaton High school. Found positive outcomes: academic results went up, illness went down. Research: Siffre, Aschoff and Wever, Folkard Case studies are diffcult to generalise. Small sample sizes and control issues in some of the studies. Individual differences: Age differences Czeisler found that circadian rhythms vary from 13-65 hours. Individuals appear to have innately different times of when their circadian cycle peaks. Duffy uses this to explain why some people rise early and go to bed early 'larks', whereas others prefer to wake and go to bed later 'owls'.

Answer 31

Supporting evidence for the role of exogenous zeitgebers in the sleep-wake cycle **VETTER ET AL**: experimental group of office workers were exposed to brighter white light (8000K - cool hue) control group were exposed to regular white lighting (4000K - warm hue). Found sleep/wake pattern in the experimental group synchronised to the brighter office lighting, whereas in control group-> remained synchronised to natural sunlight. findings suggest that light = dominant zeitgeber for the human clock and the effect depends on its hue. - Supporting evidence for the role of exogenous zeitgebers in the sleep-wake cycle **CAMPBELL & MURPHY**: measured effect of light shone behind the knee (exogenous zeitgeber) on body temperature & melatonin concentrations (endogenous pacemakers). found that light stimulus directly influenced the endogenous circadian clock causing it to shift. findings support the role of exogenous zeitgebers on the circadian rhythm also suggest that the biological route of this influence does not have to be via the eyes. CP: light presented to the back of the knee may have also been perceived by the eyes -> decreases internal validity of measurements taken Laboratory-based research such as this lacks ecological validity because in a more natural setting, numerous zeitgebers such as working patterns & meal times simultaneously influence an individual. limits the generalisability of the findings - practical application to mobile phone use. bright white light (cool hue) used by LED mobile phone screens can reset SCN activity-> reduces melatonin production & prevents person from becoming sleepy. Mobile phone users can be advised to avoid using their device in the hours before sleep mobile phones include a "night mode" -> dims screen & provides a warm hue filter to prevent brighter cool hues from disrupting the onset of sleep application highlights advantage of reducing the complexities of sleep-wake cycle to focus on role of light Social cues: - **Klein and Wegmann** (1974) found that the circadian rhythms of air travelers adjusted more quickly if they went outside more at their destination - exposed to more social cues of their new time zone. - Alternate argument: endogenous pacemakers/biological clock. Siffre

Answer 32

A technique for measuring brain activity. It works by detecting changes in blood oxygenation and flow that indicate increased neural activity. Strengths: - Noninvasive as it does not involve the insertion of instruments into the body, nor does it expose the body to harmful radiation. - High resolution imaging - Offers a more objective and reliable measure of psychological processes than is possible with verbal reports and can be used to measure psychological phenomena that people would not be capable of providing in verbal reports. Limitations: - Because FMRI measures changes in blood flow in the brain, it is not a direct measure of neural activity in particular brain areas. Cause and effect cannot be established. -Expensive = limited access - Lacks temporal resolution as image appears 5 secs behind the activity. - FMRI overlooks the networked nature of brain activity, as it focuses only on localised activity, ignoring the importance of communication among the different regions, which may be critical to mental function.

Answer 33

A method of recording changes in the electrical activity of the brain using electrodes attached to the scalp. Strengths: - Strong temporal resolution: Provides a recording of the brain's activity in real time rather than a still image of the passive brain. Can accurately measure a particular task or activity with the brain activity associated with it. - Useful in clinical diagnosis, e.g. by recording the abnormal neural activity associated with epilepsy or sleep disorders. Epilepsy is characterised by random bursts of activity in the brain. Limitations: - Only detects the activity in superficial regions of the brain (the cortex), cannot reveal what is going on in the deeper regions such as the hypothalamus or hippocampus - Poor spatial resolution - Electrical activity can be picked up by several neighboring electrodes, therefore the EEG signal is not useful for pinpointing the exact source of activity. Doesn't allow researchers to distinguish between activities originating in different but closely adjacent locations in the brain.

Answer 34

A technique that takes raw EEG data and uses it to investigate cognitive processing of a specific event. It achieves this by taking multiple readings and averaging them in order to filter out all brain activity that is not related to the appearance of the stimulus. Strengths: - Temporal Resolution: An advantage of the EEG/ERP technique is that it has good temporal resolution: it takes readings every millisecond, meaning it can record the brain's activity in real time as opposed to looking at a passive brain. - Because ERP's provide a continuous measure of processing in response to a stimulus, it makes it possible to determine how processing is effected by a specific experimental manipulation (i.e. during the presentation of a visual stimulus). Can measure the processing of a stimuli even in the absence of a behavioural response. - Non-Invasive Limitations: - Only sufficiently strong voltage changes across the scalp are readable and important electrical activities occurring deep in the brain are not recorded - lack of spatial precision. - Lack of standardisation in research, as all background noise and extraneous material needs to be eliminated and this may not always be easy to achieve.

Answer 35

Ways of examining the brains of people who have shown particular psychological abnormalities prior to their death in an attempt to establish the possible neurobiological cause for this behaviour. Strengths: - High spatial resolution: Allow for more detailed examination of anatomical and neurochemical aspects of the brain than would be possible with with non-invasive techniques like FMRI and EEG. Can examine deeper regions of the brain such as the hypothalamus and hippocampus. - Broca & Wernicke both used post-mortems to gain initial insight into language. Improves medical knowledge and helps generate hypothesis for further studies. Limitations: - Studies retrospectively so cannot show cause and effect. Observed damage to the brain may not be linked to the deficits under review but t some other unrelated trauma or decay. - Because people die in a variety of circumstances and at varying stages of disease, these factors can influence post-mortem studies. post-mortem delay, drug treatments and age can be confounding influences between cases and controls. - Patients with brain abnormalities may not be able to provide informed consent - raises ethical issues. (i.e. HM lost his ability to form memories was not able to provide consent but a post-mortem was still carried out on his brain).

Answer 36

A biological rhythm with a frequency of less than once cycle in 24hrs. May be weekly, monthly or annually. Examples: Weekly rhythms: male testosterone shows a weekly cycle Monthly rhythms: menstrual cycle (28-day cycle primarily influenced by hormones). Annual rhythms: Seasonal Affective disorder/SAD (seasonal depression, usually begins in early winter and mood returns in summer)

Answer 37

A biological rhythm with a frequency of more than one cycle ever 24hrs. Example: Cycles of sleep: The cycle repeats itself every 90 minutes BRAC - 90 minute cycle continues throughout the day.

Answer 38

Support for exogneous zeitgibers in menstrual cycles - Observed that the cycles among her dormitory friends at uni became synnchronised. - Involved 29 women with a history of irregular periods. Samples of pheromones were gathered from 9 of the women at different stages of their menstrual cycle, via a cotten pad placed under their armpit. Pads were rubbed on the upper lip of other pps (on day 1, pads from the start of the cycle were applied to all 20 women, on day 2 all were given a pad from the 2nd day of the cycle and so on). - F: **68%** of women experienced changes to their cycle which brought them closer to the cycle of their 'odour donor'.

Answer 39

Support for the role of exogenous zietgibers in SAD - Practical Applications Context: psychologists have hypothesised that melatonin is implicated in the cause of SAD. During winter, the lack of morning light means that melatonin secretion continues longer & this is thought to have a knock-on effect on the production of seritonin in the brain. The light produced by the lightbox works by mimicking the natural sunlight that is missing during the darker winter months, to help regulate the body's natural sleep-wake cycle and improve mood. Is thought to reset melatonin levels in people with SAD and increases the production of serotonin. Relieves symptoms in up to **60%** of sufferers (**Eastman et al**). However, the same study recorded a placebo effect of **30%**, casting doubt on the chemical influence of phototherapy.

Answer 40

Consists of 4 stages and the cucle repeats itself every 90-100 minutes. Non REM 1: Light sleep. Muscles activities slows down. Ocassional muscles twitches. Involves alpha waves. Non REM 2: Breathing pattern & heart rate slows. Slight decrease in body temp. Involves alpha waves. Non REM 3: Deep sleep begins. Brain begins to generate slow delta waves. Non REM 4: Very deep sleeping. Rhythmic breathing. Limited muscle activity. Brain produces delta waves. REM sleep: Brainwaves speed up and dreaming occurs. Muscles relax and heart rate increases. Breathing is rapid and shallow. Produces Beta waves and brain activity during REM is similar to that of an awake brain.

Answer 41

- Used EEG to identify the systematic changes in brain waves that occur at regular intervals during sleep. 9 male pps spent up to 6 nights in a laboratory. - F: 2 distinct kinds of sleep; REM sleep (where rapid eye movements occur) & NREM sleep (no rapid eye movements). The average time spent in on ultradian cycle (one complete NREM & REM cycle) was approx. **90 minutes**.

Answer 42

Exogenous Zeitgebers: - **Campbell & Murphy** demonstrated that light levels are not only processed by the eyes but also by receptors on the skin. 15 pps were woken at various times throughout a 24hr period. A light pad was then pressed against the back of the pps knees. The changes in light produced a 3hr difference in some pps usual sleep/wake cycles, despite the fact that no visual stimulation was used. Supports the role of light as an exogenous zeitgeber in circadian rhythms. Eval: May have been affected by pressure of light bad against skin - decreases validity. Chance that some eye still enter the eys. Small sample size and short-term (24hr) study. - **Eastman** investigated the treatments of SAD. Offered sufferers phototherapy (a lightbox that produces strong light in the morning and evening). F: Phototherapy reduced SAD symptoms in **60%** of cases. However, the use of a placebo (sham-light generator) produced similar results in **30%** of patients reporting a reduction in symptoms, challenging the validity of the study - may have been confounding variables. - **McClintock**: Support for exogneous zeitgibers in menstrual cycles. Observed that the cycles among her dormitory friends at uni became synnchronised. - Involved 29 women with a history of irregular periods. Samples of pheromones were gathered from 9 of the women at different stages of their menstrual cycle, via a cotten pad placed under their armpit. Pads were rubbed on the upper lip of other pps (on day 1, pads from the start of the cycle were applied to all 20 women, on day 2 all were given a pad from the 2nd day of the cycle and so on). **68%** of women experienced changes to their cycle which brought them closer to the cycle of their 'odour donor'. Enodgenous pacemakers: - **DeCoursey et al** destroyed the connections the SCN in 30 chipmunks. The SCN plays a critical role in maintaining biological rhythms & acting as an internal body clock. As a consequence, the sleep/wake cycles of the chipmunks completely disappeared. Many of the chipmunks died as a result, likely killed by predators as they were awake and vulnerable to attack when they should have been sleeping. Although they remained in dens, the restlessness of wakened chipmunks may have led to the nocturnal predation. Animal study - difficult to extrapolate findings to humans. - **Ralph et al.** Genetically altered hamsters to produce a sleep/wake cycle of 20hrs instead of 24hrs. Took mutated SCN tissue cells from the mutated hamsters and transplanted them into healthy hamsters. After the transplant, the new hamsters began to follow the same 20hr sleep/wake cycle. All hamsters were kept in laboratory conditions with the normal light/day cycle. Laboratory study = highly controlled, animal study = difficult to extrapolate.