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biopsych [paper 2] Flashcards

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1
Q

function of the CNS

A

controls and regulates all the physiological processes of the individual

eg simple things like breathing and eating
eg complex things, thinking

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2
Q

things that make up the CNS

A

brain and spinal cord

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3
Q

function of spinal cord

A

relays info between brain and body
- also responsible for simple reflex actions which dont involve the brain

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4
Q

function of the brain

A
  • divided into 2 hemispheres
  • contains the thalamus and hypothamalous – regulating appetite and fight or flight response
  • brains outer layer is cerebal cortex which is highly developed in humans, distinguishes us from lower aniamls
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5
Q

what is the peripheral nervous system

A
  • relay messages from the CNS to the rest of the body
  • made up of somantic and autonomic nervous system
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6
Q

what is teh somatic nervous system

A
  • important for voluntary movement
  • made up of nerves extending from the brain and spinal cord
  • made up of sensory receptors that carry info to the brain and spinal cords
  • and motor pathways that allow the brain to control movement in muscles
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7
Q

what is the autonomic nervous system

A
  • made of motor pathways
  • transmits messages to and from the internal organs and regulates involuntary actiosn eg digestion, heart rate or breathing
  • the ANS is made up of the sympathetic nervous system and the parasympathetic system
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8
Q

what is the sympathetic nervous system

A
  • dealing with emergencies such as fight or flight
  • neurons from SNS travel to organs+glands around the body and prepare the body for action
  • in response to stress the heart rate and blood pressure will increase and digestion is less imp. so slows down
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9
Q

what is the parasympathetic nervous system

A
  • returns body to normal after fight or flight
  • slows down breathing rate, heart rate and blood pressure
  • any previosuly slowed down functiosn are sped up eg digestion
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10
Q

the endocrine system

A
  • works alongsidethe CNS to control vital functiosn in teh body - its a network of glands that produce hormones
  • function is to secrete hormones that regukate body functions- uses blood vessels to transport these hormones.
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11
Q

glands in endocrine system

A
  1. the pituitary gland
  2. the testes and ovaries
  3. the adrenal gland
  4. teh pineal gland
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12
Q

what does the pituitary gland do

A
  • hypothalamus is connected to the pituitary gland and is responsible for controlling release of hormones from pituitary galnd
  • hormones realised by the pituaitray gland control and stimultae the release of hormones from other glands in the endocrine systme
  • diveided into anterior and posterior lobees
  • key hormone realsed from posterio lobe is oxytocin
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13
Q

function of oxytocin

A
  • induces labour contractions+lactactions and used to artificiallly induce labour
  • realeased with touch and hugs and is thought to play a role in mother child bonding
  • realeased by both men and women during touching and sex, deepening feelings of trust and attachemnt and making couples feel closer and more bonded
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14
Q

study on effect of oxytocin on behaviour

A

inhibiting oxytocin in lab rats makes new mums reject their young; and oxytocin injected into females who’d never mated, made them show nurturing behaviour – reduced sensistivity to oxytocin could be a factor in child abuse

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15
Q

the testes

A

male reproductive glands and produce testosterone. testorone:
1. aggression
2. sex drive
3. deepening of voice

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16
Q

the ovaries

A

female reproductive organ, produces eggs, oestrogen and progesterone.

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17
Q

the adrenal gland

A
  • divided into 2 parts: adrenal medulla and adrenal cortex
  • medulla is responsible for realising adrenalien and noradrenaline which plays a key role in the fight or flight response
  • cortex releases cortisol which stimulates the release of glucose to proved body with energy while suppressing the immune system
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18
Q

process of fight or flight

A
  1. threat is perceived: the amygdala recognises a threat and the hypothalamus is activited
  2. the hypothamalus commands the ANS and activates the sympathetic branch
  3. the piturary gland releases ACTH, this affets the adrenal medualla causing them to release adrenaline into the blood
  4. adrenaline the causes physiologicla chnages necessary for fight or flight . eg increased heart rate, pupil dilation and increased breathing rate, reduction of non-essention functions like digestion
  5. following fight or flight the parasympathetic nervous systme activates to return to its resting state
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19
Q

eval. of flight or fight

A
  1. may not be first reaction to threat- GRAY (1998) argued animals and human display initial ‘freeze response’ where they’re hyper=alert to danger; allows to gather info and assess situation
  2. research typically conducted on males– TAYLOR ET AL (2000) suggests women may be inclined to ‘tend and befriend’ , involves protecting their children and forming alliances with other women or even their attcakers
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19
Q

function of sensory neuron

A
  • sense things eg light, temp
  • takes messages from organs to CNS
  • sends info to relay neurone
  • afferent = carry nerve implulses from sense receptors to CNS
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20
Q

structure of sensory neurone

A

unipolar

meaning only one branch off of the cell body

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21
Q

function of relay neurones

A
  • recieve info from sensory neurons
  • make decisions about processes in body
  • sends info to motor neuron
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22
Q

structure of relay neurone

A
  • found in CNS
  • multipolar

multipolar = multiple dendrites coming off of cell body

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23
Q

function of motor neurons

A
  • relays info from relay neurons
  • send info to effectors - eg glands or muscles
  • efferent = carry info away from CNS
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24
Q

structure of motor neurons

A

multipolar

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25
Q

reflex arc

A
  • when a very quick response is needed, brain is not needed and is a function of the spinal cord
  • when the safety of an organism demands a very quick response, the signals may be passed directly from a sensory neurone via a relay neurone, to a motor neurone for instant unthinking action – this is a reflex action, a reflex arc is the nerve pathway which makes such a fast, automatic response possibel
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26
Q

process of synaptic transmisison

A
  1. action potential arrives in pre-synaptic neuron via traveeling down the axon
  2. action potential stimulates vesicles
  3. vesicles relaease neurotransmitters into the synaptic cleft
  4. neurotransmitters diffuse over synaptic cleft
  5. neurtransmitters bind to receptors and activate them
  6. reuptake- excessive neurotransmitters are taken up by the pre-synaptic neurone
  7. enzymes are released to break down the remaining neurotransmitters + diffusiomm
  8. vesicles are replenished with new+reused neurotransmitters ans allows action potential to get from pre to post
  9. summation occurs, some neurotransmitters are excitatory, some are inhibitary. if there are more excitatory another action potential may occur.
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27
Q

what do excitatory neurotransmitters do?

A
  • trigger nerve impulses that stimulate brain activity
  • results in excitatory post-synaptic potential and increase likelihood of the post-synaptic neuron firing eg dopamine can increase motivation and reward
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28
Q

what do inhibitatory neurotransmitters do?

A
  • inhibit nerve impulses and have a calming effect on the brain
  • results in inhibitory post-synaptic potential and decreases the chance of the post-neuron firing
  • eg serotonin has a stabalising effect on mood
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29
Q

where is the motor cortex

A

frontal lobe, both hemispheres

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30
Q

function of motor cortex

A
  • regulate movement
  • damage to this area may result in loss of movemnet in particular areas
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31
Q

location of somatosensory cortex

A

parietal lobe, both hemispheres

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32
Q

location of auditory cortex

A

temporal lobe, both hemispheres

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33
Q

location of visual cortex

A

occipital lobe, both hemispheres

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34
Q

location of broca’s area

A

frontal lobe, left hemisphere

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35
Q

location of Wernicke’s area

A

temporal lobe, left hemipshere

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36
Q

function of somatosensory cortex

A
  • processes sensory info eg touch and heat
  • the more sensitive the body part, the bigger the area in the somatosensory cortex
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37
Q

function of auditory cortex

A

analysis of sound+speech based info

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38
Q

function of visual cortex

A
  • visual info from each eye
  • right visual field to left visual cortex
  • left visual field to right visual cortex
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39
Q

function of Broca’s area

A

speech production

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40
Q

function of Wernicke’s area

A

comprehensions of language

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41
Q

supporting evidence for localisation of language centres

A

peterson et al –
* used brain scans to demonstrate hoe brocas was active during a reading task and wernickes was active during a listening task
* supports idea that there are diff part of the brain are responsibke for diff aspects of speech

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42
Q

supporting evidence for role of hippocampus

A

MAGURIE ET AL
* used MRI scans on cab drivers
* increased volume found in posterior hippocampus
* correlation was found between amount of time spent as a taxi driver and volume in right posteriori hippocampus
* provides objective evidence that brain functions are localised

43
Q

plasticity as weakness to localisation of function

A

plasticity- anyway the brain changes itself due to chnages within the body or external enviro
* brain can reoragnaise itself and parts of the brain may take over the functiosn of the damaged part

44
Q

opposing evidence for localisation of function

A

lashley
* removed various areas of cortex in rats
* rats then learnt a maze
* area of cortex removed made no differnce in rats ability to learn the maze, suggesting that no area was any more important than any other in terms of spatial and navigational memory
* suggests that learning is to complex to be localised and are distributed in a more holistic way in the brain

45
Q

Sperry’s split brain research

A
  • 11 P’s who’d had surgery to sever the corpus callosum due to epilepsy, compared to control group of non-epelieptic, non split brain patients
  • general procedure in which an image, word (using a tachistoscope for 0.1 secs), or object could be projected or given to a patient to be processed by a particular hemisphere
46
Q

Sperry’s split brain research findings

A
  • visual task - when info was shown to patients right visual field ( left hemi) the patient could describe it ; if shown to left visual field they couldnt describe it and often insisted they didnt see anything
  • tactile task - could name+describe objects in right hand (left hemi) but when placed in left hand they couldn’t name or describe it
47
Q

eval of Sperry’s split brain research

method

A
  • highly scientific
  • standardised procedure
  • study was well contained to ensure info was recieved by one hemi and incraese the reliability of the data
48
Q

eval of Sperry’s split brain research

generalisability

A
  • only 11 people, and all had a history of epileptic seizures – argued that this could have caused unique changes in their brain that might have influenced the findings
  • CONTROL GROUP – argued that a more valid group would be epileptic people who had not had the operation – epilepsy or the drugs used to treat epilepsy may have affected the patients brain irrespective of the split-brain procedure and could be responsible for the results
49
Q

eval of Sperry’s split brain research

language

A

TURK ET AL
* studied a patient who suffered damage to the left hemi but developed capacity to speak in the right hemi
* suggests lateralisation is not fixed and that the brain can adapt following damage to certain areas

50
Q

eval of Sperry’s split brain research

age

A

SZAFLARKI
* lang became more lateralised to left hemi with increasing age in children and adolescents
* but after 25, lateralisation decreased with each decade of life
* emphasisies complexity in regards to research into hemispheric lateralisation

51
Q

what is plasticity

A

brains tendency to change+adapt as a result of experince and learning
* plays imp. role in brain developmemnt and behavior

52
Q

whta is functional recovery

A
  • a form of plasticity
  • following trauma, the brain’s ability to distribute/transfer functions usuually performed by damages areas
53
Q

how can functional recovery be achieved

A

done through process called neuronal masking where dormant synapses open connections to compensate for damaged area

54
Q

what is localisation of brain function

A

Localisation of function refers to identifying specific areas of the brain that correspond to specific functions. For example, damage to the auditory cortex in the brain can damage hearing, whereas damage to the motor cortex may reduce a person’s ability to move. This suggests these functions are localised within these areas of the brain.

55
Q

what is the motor cortex

A

The motor cortex of the brain is responsible for voluntary movement, such as walking. It is located in the frontal lobes of each hemisphere. However, basic involuntary movements (like coughing) are controlled by other parts of the brain.

So, damage to the motor cortex may limit a person’s motor skills. For example, a person with a damaged motor cortex may have difficulty holding a pen.

56
Q

what is the somatosensory cortex

A

The somatosensory cortex of the brain is responsible for sensing physical sensations on the skin, like pressure and heat. It is located in the parietal lobes of each hemisphere.

The number of neurons in the somatosensory cortex differs according to body part. For example, there are many more neuronal connections dedicated to processing information from the hands than the ankles because people use their hands to feel things much more commonly than they do their ankles.

57
Q

what is the visual cortex

A

The visual cortex of the brain is responsible for processing visual information from the eyes. It is located in the occipital lobes of each hemisphere. The visual cortex is contralateral: The right hemisphere processes data from the left of a person’s field of vision (both eyes) and vice versa.

So, damage to the visual cortex of the right hemisphere may make it difficult for a person to perceive objects to the left of them.

58
Q

what is the auditory cortex

A

The auditory cortex of the brain is responsible for processing sound. It is located in the temporal lobes of each hemisphere. The auditory cortex is also contralateral: The right hemisphere processes sound from a person’s left ear and vice versa.

So, damage to the auditory cortex of the left hemisphere may cause hearing difficulties in a person’s right ear.

59
Q

what are the two language centres

A
  1. broca’s area
  2. wernicke’s area
60
Q

where is the motor cortex

A

located in the frontal lobes of each hemisphere.

61
Q

where is the somatosensory cortex

A

It is located in the parietal lobes of each hemisphere

62
Q

where is the visual cortex

A

It is located in the occipital lobes of each hemisphere. The visual cortex is contralateral: The right hemisphere processes data from the left of a person’s field of vision (both eyes) and vice versa.

63
Q

where is the auditory cortex

A

located in the temporal lobes of each hemisphere

64
Q

what is broca’s area

A

The Broca’s area is the main area where speech is produced. It is located in the frontal lobe of the left hemisphere.

The Broca’s area was identified by and named after Pierre Paul Broca in the mid 19th Century. From post-mortem autopsies, Broca observed that patients who’d had difficulty producing words had lesions (damage) in this area of the brain.

Damage to the Broca’s area causes Broca’s aphasia (also called expressive aphasia), a condition characterised by slow speech, lack of fluency, and an inability to find the right words. Despite difficulties producing speech, people with Broca’s aphasia often have normal language comprehension – i.e. they understand what others are saying.

65
Q

where is broca’s area

A

frontal lobe of the left hemisphere

66
Q

what is wernicke’s area

A

Another important (but separate) area for language is Wernicke’s area. The Wernicke’s area is primarily responsible for language comprehension (both written and spoken). It is located in the temporal lobe.

Damage to the Wernicke’s area causes Wernicke’s aphasia (also called receptive aphasia). Patients with Wernicke’s aphasia typically have no problems producing speech – they speak in a fluent and effortless way – but the content of what they say often lacks meaning.

67
Q

where is wernicke’s area

A

located in the temporal lobe

68
Q

what does damage to wernicke’s area lead to

A

Wernicke’s aphasia (also called receptive aphasia). Patients with Wernicke’s aphasia typically have no problems producing speech – they speak in a fluent and effortless way – but the content of what they say often lacks meaning.

69
Q

strengths of localisation of function

A

Evidence supporting localisation of function:
Case studies: Several case studies support the claim that different functions within the brain are localised in specific areas. Perhaps the most famous example is Phineas Gage, a 19th century railroad worker. Gage had an iron bar shot straight through his head during an accident while working, which damaged the left frontal lobe of his brain. Before the accident, Gage was calm and polite, but after the accident Gage was violent and rude (however, some accounts claim these characterisations are exaggerated). Gage’s doctor believed the damaged area (the left frontal lobe) was responsible for self-control, which was confirmed by later research into localisation of function.
Brain scans: fMRI scans demonstrate correlations between different mental activities and different areas of the brain. For example, Ovaysikia et al (2011) demonstrates increased blood flow in different areas of the brain depending on whether a person is reading words or recognising facial expressions.

70
Q

weaknesses of localisation of function

A
  • Higher cognitive processes: Higher cognitive processes such as learning, language, and memory are seemingly too complex to be localised within a single area. For example, Lashley (1950) removed different parts of rats brains while they were learning a maze but found no single area was most important. This suggests higher cognitive processes (e.g. learning) are distributed in a holistic way within the brain, rather than being localised in a single area.
  • Neuroplasticity: The fact that the brain can recover functions after damage to areas associated with that function suggests that mental activities are not localised in these areas. For example, language is supposedly localised within the the left hemisphere, but Danelli et al (2013) – see functional recovery after trauma below – describes the case study of a boy who had his entire left hemisphere removed and yet learned to speak.
  • Methodological concerns: Cases studies (e.g. Phineas Gage) use a sample size of just one and so it may not be valid to generalise findings from case studies to the entire population of human beings.
71
Q

functional recovery after trauma

A

Neuroplasticity enables people to recover function after trauma (e.g. brain damage caused by stroke or accident). To recover function, the brain restructures itself in the following ways:

  • Other areas of the brain adapt to take over the function of damaged areas: For example, Danelli et al (2013) describes a case study of a boy who had his entire left hemisphere removed at age 2 and a half. As described above, language function is primarily localised in this hemisphere, and the boy was initially unable to speak. However, his language skills recovered after 2 years, suggesting the right hemisphere adapted to take over this function.
  • Unused neural pathways are recruited: Wall (1977) observed that the brain contains many dormant neural connections. When healthy neural connections are damaged, these previously dormant synapses activate and form new connections to compensate for the damaged ones.
  • Axon sprouting: Damage to the axon of a neuron can break its connections to neighbouring neurons. When this happens, the neighbouring intact neurons may grow (‘sprout’) extra nerve endings to reconnect with these damaged neurons.
72
Q

A03 of neuroplasticity

A
  • Evidence supporting neuroplasticity: Several studies demonstrate the brain’s ability to change its physical structure to perform different functions. In addition to the studies above, brain scans by Maguire et al (2000) found that London taxi drivers had a higher volume of grey matter in the posterior hippocampus (an area associated with spatial memory and navigation) compared to controls. This suggests this area of the brain adapted in cab drivers to help them with their work.

Variations between people: Neuroplasticity and the ability of the brain to recover function after damage differs depending on several factors, such as:
* Age: The brain tends to lose neuroplasticity with age. For example, Danelli et al (2013) demonstrates that young people can recover function even after extensive damage to the brain, but it’s highly unlikely that an older patient could recover from such extensive damage. However, Bezzola et al (2012) found evidence of neural changes in participants aged 40-60 following 40 hours of golf training. This suggests neuroplasticity still exists to some extent even among older adults.
* Gender: Some research (e.g. Ratcliff et al (2007)) suggests women are better able to recover function after brain damage than men. A possible explanation of this is that female brains have (on average) more neural connections between the left and right hemispheres than men, resulting in more distributed use of both hemispheres. This reduced hemispheric lateralisation would mean the other hemisphere is better able to compensate for the functions of the damaged hemisphere.

73
Q

what are ways of studying the brain

A
  1. FMRI
  2. ERPS
  3. EEG
  4. Post-mortem
74
Q

what is an FMRI

A

Functional magnetic resonance imaging (fMRI) is a form of brain scanning. It** uses magnetic fields to measure blood flow and oxygenation in the brain**.

When an area of the brain is highly active, that area needs more oxygen and greater blood flow to provide this oxygen. By measuring blood flow and oxygenation, fMRI scanners enable researchers to identify which areas of the brain are activated during certain tasks

The example fMRI scans above are from Ovaysikia et al (2011). In this study, the researchers measured brain activity during two tasks: Reading words and recognising facial expressions. As can be seen from the fMRI scan above, the different tasks increased brain activity in different areas.

75
Q

strengths of FMRI

A
  • Dynamic: fMRI scans record brain activity as it happens, which enables researchers to see activity in the brain over time (unlike post-mortem). For example, when a person switches from working out a maths equation to thinking about a childhood memory, fMRI scanners can pick up the change in brain activity.
  • High spatial resolution: fMRI scans are able to identify activity in the brain to within 1mm. This provides a highly detailed and accurate picture of brain activity (much more so than EEG).
76
Q

weaknesses of FMRI

A
  • Expensive: fMRI scanners are expensive to buy and maintain (compared to EEG). This limits their use as psychological research tools, with studies that do use fMRI scanners often consisting of small sample sizes in order to reduce costs.
  • Low temporal resolution: It takes several seconds between recording brain activity using fMRI and converting it into an image. This means fMRI generates fewer images per minute (compared to e.g. EEG) and brain activity between each image is not recorded.
77
Q

what is an EEG

A

a scan of the brain’s electrical activity. An EEG scan is performed by attaching electrodes to the scalp or by using a hat with electrodes attached.

The electrodes detect electrical activity in the brain cells beneath them. So, the more electrodes that are used in an EEG, the more complete a picture of brain activity the EEG can provide.

78
Q

what is an ERP

A

Event-related potentials (ERPs) are closely related to EEG scans. They use the same equipment but use statistical techniques to measure changes in brain activity in response to a stimulus. For example, the EEG could initially provide a baseline picture of brain activity, then researchers could introduce a stimulus (e.g. giving a subject some food to eat) and use ERPs to determine how brain activity changed in response.

79
Q

strengths of EEG’s and ERPS

A
  • Dynamic: Like fMRI, EEG and ERPs enable researchers to measure changes in brain activity as they happen.
  • Lower cost: EEG brain scans are much less expensive than fMRI brain scans.
  • Higher temporal resolution: EEG can record several pictures of the brain per second, unlike fMRI.
80
Q

weaknesses of EEG’s and ERPS

A

Low spatial resolution: The electrodes of EEG only measure general electrical activity and are unable to provide a detailed view of what is happening in the brain (unlike fMRI). For example, neurons associated with feeling in the hands may be next to neurons associated with hearing, but the EEG will not be able to differentiate between the two. However, some psychological conditions have distinctive electrical signals (e.g. epilepsy) and so EEGs are useful diagnostic tools for them.

81
Q

what is post mortem

A

A post-mortem is a physical examination of the brain after a person has died. By physically analysing a brain (for example, by weighing it, dissecting parts of it, and comparing it to neurotypical (‘normal’) brains) and cross-referencing this with the person’s behaviour in life (e.g. any psychological disorders the person had) the examiner can learn more about the causes of behaviours and psychological disorders.

82
Q

strengths of post-mortem

A

Post-mortems enable researchers to study deeper areas of the brain that cannot be reached, for example, by EEG.

83
Q

weaknesses of post-mortem

A

No brain activity: As the person is dead, a post-mortem does not enable researchers to measure dynamic brain activity (unlike fMRI and EEG). As such, researchers may have to speculate about (rather than measure) connections between the person’s physical brain and their psychological character (e.g. psychological conditions) when they were alive.

84
Q

what are the 3 types of biological rhythms

A
  1. circadian
  2. infradian
  3. ultradian
85
Q

length and example of circadian rhythms

A

24hrs
e.g sleep and wake cycle

86
Q

length and example of infradian rhythms

A

more than 24hrs
e.g menstrual cycle

87
Q

length and example of ultradian rhythms

A

less than 24hrs
stages of sleep

88
Q

what controls biological rhythms

A

Biological rhythms are controlled by endogenous pacemakers, which are influenced by exogenous zeitgebers

89
Q

what are exdrogenous pacemakers

A

Things within the body that regulate biological rhythms (your ‘body clock’).
* E.g. The suprachiasmatic nucleus of the hypothalamus

90
Q

what are exdrogenous zeitgebers

A

Cues in the external environment that inform endogenous pacemakers to regulate biological rhythms.
* E.g. Sunlight and darkness prompt the body to release hormones that control sleep and wake cycles

91
Q

A03 of exdrogenous pacemakers and exdrogenous zeitgebers

A
  • Examples of the effect of exogenous zeitgebers: Campbell and Murphy (1998) conducted an experiment where participants were woken up in the middle of the night. After waking, one group had light shone onto the back of their knees whereas the control group went through the same procedure but the lightbulb was unplugged. The researchers observed that the group who’d had light shone on the backs of their knees had a greater deviation from their original circadian rhythm compared to the control group. This demonstrates the importance of the exogenous zeitgeber of light (even when shone on the skin rather than the eyes) for regulating circadian rhythm.
  • Examples of the effect of endogenous pacemakers: Ralph et al (1990) transplanted cells from the suprachiasmatic nucleus of hamsters with a 20-hour circadian rhythm into normal hamsters with a 24-hour circadian rhythm. This shortened the circadian rhythms of these hamsters to 20 hours from 24, which illustrates the importance of this endogenous pacemaker in maintaining circadian rhythms. However, as an animal study, these findings may not be valid when applied to humans.
  • Relative importance: Endogenous pacemakers appear to be more important than exogenous zeitgebers in regulating circadian rhythms. There are many studies where circadian rhythms remain regular despite significant disturbances to exogenous zeitgebers (see the AO3 evaluation points for circadian rhythms for examples).
92
Q

what are circadian rhythms

A
  • Circadian rhythms are biological cycles lasting approximately 24 hours. An example of a circadian rhythm is the sleep/wake cycle: You might cycle between sleeping for 8 hours when it gets dark and being awake for 16 hours during the day, for instance.
  • Examples of endogenous pacemakers that control circadian rhythm include systems that release hormones such as melatonin, systems that regulate body temperature, and systems that control metabolism and digestion. The main system that controls circadian rhythms is the suprachiasmatic nucleus (SCN).
  • These internal processes are influenced by exogenous zeitgebers – perhaps the most obvious of which is sunlight. For example, the darkness of night is thought to** trigger melatonin release, which makes you feel tired and want to go to bed.**
93
Q

A03 of circadian rhythms

A

Endogenous pacemakers appear to be more important than exogenous zeitgebers in regulating circadian rhythms. There are many studies where circadian rhythms remain regular despite significant disturbances to exogenous zeitgebers. For example:
* Speleologist Michael Siffre conducted several case studies (using himself as a subject) on the effects of living in a cave without the exogenous zeitgeber of natural light. In 1962, he spent two months in a cave without any natural light and without a clock. Then, in 1975, he conducted a similar experiment but for six months. In both experiments, Siffre maintained a regular sleep/wake cycle and circadian rhythm of around 25 hours.

  • Aschoff and Wever (1976) conducted an experiment where participants were kept in a World War 2 bunker without any natural light for four weeks. All participants (except one) maintained a circadian rhythm very close to 24 hours, despite the absence of natural light.
  • Folkard et al (1985) conducted a similar experiment where participants were kept in a cave without sunlight for three weeks. The participants were supposed to go to bed when a clock said 11:45pm and wake when it said 7:45am, but unbeknown to them the researchers slowly increased the clock speed so that what seemed like a 24-hour day was actually only 22 hours. Despite these faster clocks, all but one participant maintained a consistent 24 hour circadian rhythm.
  • Practical applications: Understanding circadian rhythms can help improve the sleep and health of shift workers, for example. Czeisler et al (1982) found that employees whose shifts were stable over 21 days or more had greater employee satisfaction, improved health estimates, and were less likely to leave their job than employees whose work schedules changed every week. This is likely because keeping shift schedules over 21 days or more allowed workers’ circadian rhythms to adjust to their work schedules. This knowledge can be used by businesses that employ workers on shifts to improve employee satisfaction and reduce employee turnover.
  • Methodological concerns: Much of the research on circadian rhythms is in the form of case studies or experiments using small sample sizes. As such, these findings may not be valid when applied to the general population.
94
Q

what are infradian cycles

A

Infradian rhythms are biological cycles lasting more than 24 hours. An example of an infradian rhythm is the human menstrual cycle: Women typically ovulate once every 28 days.

As with circadian rhythms, infradian rhythms are controlled by endogenous pacemakers. For example, hormones such as estrogen and progesterone are crucial to the menstrual cycle.

Infradian rhythms can also be influenced by exogenous zeitgebers. For example, Stern and McClintock (1998) demonstrated that women’s menstrual cycles change when exposed to pheromones from other women.

95
Q

what are ulradian cycles

A

Ultradian rhythms are biological cycles lasting less than 24 hours. An example of an ultradian rhythm is the different stages of sleep: During the night, a sleeping person will typically cycle between five stages.

One complete sleep cycle through all these stages will typically take around 90 minutes. So, during a full night’s sleep, a person may repeat this cycle four or five times.

96
Q

length of each sleep cycle

A

stage 1: 5-15mins
stage 2: 5-15mins
stage 3: 5-15mins
stage 4: 40mins
stage 5[REM]: >15mins

97
Q

description of stage 1 of sleep cycle

A

Light sleep. Alpha waves increase and brain activity starts to reduce. Heart rate slows and muscles relax.

98
Q

description of stage 2 of sleep cycle

A

Light sleep. Brain activity reduces but with occasional bursts of activity.

99
Q

description of stage 3 of sleep cycle

A

Deep sleep. Delta brain waves increase and brain activity is greatly reduced.

100
Q

description of stage 4 of sleep cycle

A

Deep sleep. Delta waves peak, lowest level of brain activity during the sleep cycle.

101
Q

description of stage 5 [REM] of sleep cycle

A

High level of brain activity. Dreams are likely to occur. Body is completely relaxed.

102
Q

supporting evidemce for distinct stages of sleep

A

Dement and Kleitman (1957) monitored the sleep patterns of nine adult participants in a sleep lab. Brainwave activity was recorded on an EEG.
REM activity during sleep was highly correlated with the experience of dreaming, brain activity varied according to how vivid dreams were, and the participants woken during dreaming reported very accurate recall of their dreams. This suggests that REM sleep is a distinct component of the ultradian sleep cycle.

103
Q

evidence against stages of sleep

individual differences

A

The problem with studying sleep cycles is the differences observed in people, which make investigating patterns difficult. Tucker et al. (2007) found significant differences between participants in terms of the duration of each stage, particularly stages 3 and 4 (just before REM sleep). This demonstrates that there may be innate individual differences in ultradian rhythms, which means that it is worth focusing on these differences during investigations into sleep cycles.

104
Q

sleep studies lack egological avlidity

A

Sleep studies tend to take place in sleep labs

psych paper 1 (5 decks)

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