Extent of Brain Localization

This article discusses the extent to which brain functions are localized, focusing on the areas associated with specific functions such as motor control, sensory perception, language, and more. It also explores the concept of brain plasticity and functional recovery after trauma. Additionally, it delves into split-brain research and the use of scanning techniques like fMRI, EEG, ERP, and post-mortem analysis to investigate the brain.

DISCUSS THE EXTENT TO WHICH BRAIN FUNCTIONS ARE LOCALISED.
AO1
LOCALISATION VS. HOLISTIC THEORY
 19TH CENTURY: BROCA + WERNICKE discovered the SECIFIC AREAS of the brain are associated with
PARTICULAR PHYSICAL AND PSYCHOLOGICAL FUNCTIONS
 PAST: scientists supported the HOLISTIC VIEW – ALL PARTS of the brain are involved with every aspect
HEMISPHERES OF THE BRAIN AND THE CEREBRAL CORTEX
 BRAIN = 2 SYMMETRICAL HALVES called the LEFT AND RIGHT HEMISPHERES
 ACTIVITY ON THE LEFT controls that on the RIGHT SIDE OF THE BODY + vice versa
 OUTER LAYER = CEREBERAL CORTEX – what separates us from animals
THE MOTOR, SOMATOSENSORY, VISUAL + AUDITORY CENTRES
 MOTOR (BACK of FRONTAL LOBE): controls VOLUNTARY MOVEMENT in the OTHER HEMISPHERE –
DAMAGE = loss of CONTROL over FINE MOVEMENTS
 SOMATOSENSORY (FRONT of the PARENTAL LOBE): SENSORY info is REPRESENTED e.g. touch, heat
pressure
 VISUAL (OCCIPTAL LOBE): DAMAGE to the LEFT can produce BLINDNESS in part of the RIGHT VISUAL FIELD
 AUDITORY (TEMPORAL LOBE): analyses SPEECH-BASED info, DAMAGE = PARTIAL HEARING LOSS and
possible damage to the WERNICKE AREA – affect the ability to COMPREHEND LANGUAGE
THE LANGUAGE AREA OF THE BRAIN
 LANGUAGE is restricted to the LEFT SIDE
 BROCA identified an area in the FRONTAL LOBE responsible for SPEECH PRODUCTION, DAMAGE = BROCA’S
APHASIA – slow, laborious and lacking in fluency when speaking
 WERNICKE saw those with PROBEMS PRODUCNG LANGUAGE produced FLUENT but MEANINGLESS
sentences = WERNICKE’S AREA in the LEFT TEMPORAL LOBE, DAMAGE = WERNICKE’S APHASIA – produce
nonsense words
AO3

BRAIN SCAN EVIDENCE OF LOCALISATION: PETERSEN ET AL: BRAIN SCANS to show how WERNICKE’S AREA
was ACTIVE DURING LISTENING TASKS an BROCA’S AREA was ACTIVE DURING THE READING TASKS =
different areas, different functions OR TULVING ET AL: SEMANTIC and EPISODIC MEMORIES in different
parts of the PRE-FRONTAL CORTEX

NEUROSURGICAL EVIDENCE: FREEMAN: DEVELOPED LOBOTOMY – a BRUTAL, IMPRECISE and typically
involved in SEVERING CONNECTIONS in the FRONTAL LOBE to control AGGRESSIVE BEHAVIOUR //
NEUROSURGERY is used today in EXTREME CASES OF OCD + DEPRESSION – DOUGHERTY ET AL: 44 OCD
PATIENTS who underwent CINGULOTOMY – after 32 wks POST SURGERY = A THIRD had a SUCCESSFUL
RESPONSE, 14% had a PARTIAL RESPONSE = symptoms associated with mental disorders are LOCALISED

CASE STUDY EVIDENCE: PHINEAS GAGE: preparing to blast a section of rock with explosives but dropped
his TAMPING IRON onto the rock causing the explosive to IGNITE – the pole went through his LEFT OF THE
FRONTAL LOBE = SURVIVED BUT turned into someone who was QUICK-TEMPERED, RUDE from CALM and
RESERVED

LASHLEY’S RESEARCH: HIGHER COGNITIVE FUNCTIONS, e.g. LEARNING, are NOT LOCALISED but HOLISTIC –
he REMOVED areas of the CORTEX (10% -50%) in RATS that were LEARNING A MAZE = NO AREA WAS
MORE IMPORTANT – LEARNING IS TOO COMPLEX TO BE LOCALISED
DISCUSS RESEARCH INTO PLASTICITY OF THE BRAIN INCLUDING FUNCTIONAL RECOVERY

AO1
BRAIN PLASTICITY
 PLASTICITY: the brain’s tendencies to CHANGE and ADAPT as a result of EXPERIENCE and NEW LEARNING
 SYNAPTIC PRUNING: as we AGE, RARELY USED CONNECTIONS are DELETED and FREQUENTLY USED
CONNECTIONS are STRENGTHENED
 RECENTLY, research has found that at ANY TIME in life, NEURAL CONNECTIONS can CHANGE or NEW ONES
can be formed
RESEARCH INTO PLASTICITY
 MAGUIRE ET AL: studied BRAIN of the LONDON TAXI DRIVERS and found SIGNIFICANTLY MORE VOLUME
of GREY MATTER in the POSTERIOR HIPPOCAMPUS than a matched CONTROL GROUP
THIS part of the brain is associated with the DEVELOPMENT of SPATIAL AND NAVAGATIONAL SKILLS in
humans and other animals
LONDON CABBIES have to take THE KNOWLEDGE TEST which assess their recall of the CITY STREETS and
POSSIBLE ROUTED
WITH EXPERIENCE, the structure ALTERS in the brain
 DRAGANSKI ET AL: IMAGED the brains of MEDICAL STUDENTS 3 MONTHS BEFORE AND AFTER THEIR FINAL
EXAMS = LEARNING – induced changes in the POSTERIOR HIPPOCAMPUS and the PARIETAL CORTEX in the
exam
FUNCTIONAL RECOVERY OF THE BRAIN AFTER TRAUMA
 UNAFFECTED AREAS ADAPT and COMPENSATE for the areas damaged in PHYSICAL INJURY or other
TRAUMA TYPES e.g. stroke
 Happens QUICKLY (SPONTANEOUS RECOVERY) but then SLOWS DOWN after several weeks – may require
REHABILITATION THERAPY
WHAT HAPPENS IN THE BRAIN DURING RECOVERY?
 the BRAIN REORGANISES ITSELF by forming NEW SYNAPTIC CONNECTIONS close to the area of DAMAGE
through SECONDARY NEURAL PATHWAYS that wouldn’t be used otherwise (DOIDGE 2007)
 AXONAL SPROUTING: the growth of NEW NERVE ENDINGS
 REFORMATION of the BLOOD VESSELS
 RECRUITMENT of HOMOLOGOUS (similar) areas on the OPPOSITE SIDE OF THE BRAIN
AO3 PRACTICAL APPLICATION: contributed to the field of NEUROREHABILITATION – spontaneous recovery
tends to slow down after a number of weeks so forms a PHYSICAL THERAPY may be required to MAINTAIN
IMPROVEMENTS in functioning e.g. movement therapy + electrical stimulation of the brain AGE + PLASTICITY: functional plasticity tends to REDUCE WITH AGE – BEZZOLA ET AL: 40 HOURS OF GOLF
TRAINING produced changes in the NEURAL REPRESENTATION of MOVEMENT in pps aged 40-60 – used
FMRI and saw a REDUCED MOTOR CORTEX ACTIVITY in the NOVICE GOLFERS compared to the CONTROL
GROUPS = more efficient neural representations AFTER TRAINING SUPPORT FROM ANIMAL STUDIES: HUBEL + WIESEL: SEWING ONE EYE of a KITTEN SHUT and analysing the
BRAIN’S CORTICAL RESPONSES – the area of the VISUAL CORTEX associated with the shut eye continued to
PROCESS INFORMATION from the other EYE NEGATIVE PLASTICITY: the brain’s ability to REWRITE ITSELF can have MALADAPTIVE BEHAVIOURAL
CONQUENCES – PROLONGED DRUG USE = POORER COGNITIVE FUUNCTIONING as well as a HIGHER RISK
OF DEMENTIA (MEDINAETAL 2007) + 60% TO 80% of amputees have been known to develop PHANTOM
LIMB SYNDROME – the continued experiences of SENSATIONS in the MISSING LIMB = PAINFUL AND
UNPLEASANT due the REORGANISATION in the SOMATOSENSORY CORTEX (RAMACHANDRAN + HIRSTEIN)
DISCUSS SPLIT-BRAIN RESEARCH.

AO1
 the specialised areas associated with LANGUAGE are found in ONE of the brain’s HEMISPHERES rather
than BOTH and whether other processes of the brain was investigated by SPERRY
SPLIT BRAIN STUDIES (SPERRY)
 INVOLVED a group that had all undergone a COMMISSUROTOMY OPERATION where the CORPUS
CALLOSUM (which CONNECTED the two hemispheres) was cut down the MIDDLE of to control FREQUENT
and SEVERE EPILEPTIC SEIZURES
 this allowed SPERRY to see what extent to which the two hemispheres were SPECIALISED IN CERTAIN
FUNCTIONS and whether the two hemispheres performed tasks INDEPENDENTLY of each other
 used a TACHISTOSCOPE; an IMAGE or a WORD is projected on the RIGHT VISUAL FIELD (processed by the
LEFT HEMISPHERE) and the SAME or DIFFERENT IMAGE would be projected to the LEFT VISUAL FIELD
 NORMAL BRAIN: the C.C would SHARE the info between both HEMISPHERES
 SPILT-BRAIN: info couldn’t be conveyed between the two hemispheres
KEY FINDINGS
 DESCRIBING WHAT YOU SEE: picture shown on the RIGHT VISUAL FIELD = EASILY DESCRIBED / picture
shown on the LEFT VISUAL FIELD = COULDN’T DESCRIBE and often said there was nothing
= MOST PEOPLE: LANGUAGE is processed in the LEFT HEMISPHERE and there are NO LANGUAGE CENTRES
on the RIGHT HEMISPHERE SO when something is presented to the LEFT VISUAL FIELD, messages from the
RIGHT HEMISPHERE get RELAYED TO THE LEFT
 RECOGNITION BY TOUCH: able to SELECT a MATCHING or CLOSELY ASSOCIATED object from a bag using
their LEFT HAND/LEFT VISUAL FIELD – NOT able to VERBALLY IDENTIFY but could UNDERSTAND what the
object was using the RIGHT HEMISPHERE
 COMPOSITE WORDS: if TWO WORDS are presented SIMULTANEOUSLY, one on either side of the visual
field e.g. key on the left and ring on the right, they would be able to WRITE KEY with their left (using the
RIGHT HEMISPHERE as it is superior with drawing skills) and SAY RING (using the LEFT HEMISPHERE which
is linked to LANGUAGE/DESCRIBING)
 MATCHING FACES: when shown a COMPOSITE FACE, the IMAGES on the RIGHT VISUAL FIELD could be
DESCRIBED as LEFT HEMISPHERE is best at VERBAL DESCRIPTION/LANGUAGE and the IMAGE in the LEFT
VISUAL FIELD was able to be MATCHED with a face that is SIMILAR (due to the RIGHT HEMISPHERE)
AO3

DEMONSTRATED LATERALISED BRAIN FUNCTIONS: SPERRY’S work has produced an IMPRESSIVE and
SIZEABLE BODY of research findings with the MAIN CONCLUSION being that the LEFT is more for ANAYLTIC
and VERBAL TASKS + the RIGHT is for SPATIAL and MUSIC TASKS – the right CAN OLNLY PRODUCE
rudimentary words and phrases but contributes to EMOTIONAL and HOLISTIC CONTENT to language

STRENGTHS OF THE METHODOLOGY: HIGHLY SPECIALISED AND STANDARDISED PROCEDURES + the way
the words were presented was ORIGINAL as usually p’s would be asked to look at a FIXATION POINT
whilst one eye was BLINDFOLDED and the image would be flashed up for ONE-TENTH of a second which
means that the SPLIT-BRAIN PATIENT would not have TIME to move their eye across the image to spread
the INFO to BOTH SIDES OF THE FIELD/BRAIN

THEORETICAL BASIS: PROMPTED for debate about the degree of COMMUNICATION between the
hemisphere in EVERYDAY FUNCTIONING and the NATURE of CONCIOUSNESS – PUCETTI: the teo
hemispheres are so FUNCTIONALLY DIFFERENT that they represent a DUALITY of brain (HAVE TWO MINDS
which is only emphasised in split-brain research) BUT others have argued that the hemispheres are
HIGHLT INTERGRATED and BOTH are involved in MOST EVERDAY TASKS

ISSUES WITH GENERALISATION: UNUSUAL SAMPLE OF ONLY 11 PEOPLE THAT HAD A HISTORY of EPILEPTIC
SEIZURES which could have caused UNIQUE CHANGES in the BRAIN that influenced the findings and some
p’s may have experienced MORE DISCONNECTION of the two hemispheres than others
DESCRIBE AND EVALUATE SCANNING TECHNIQUES AS A WAY OF INVESTIGATING THE BRAIN

AO1
FRMI
 MEASURES CHANGES in the BRAIN ACTIVITY while a person PERFORMS
 it measures the BLOOD FLOW in PARTICULAR AREAS of the BRAIN
 BRAIN IS ACTIVE = MORE ENERGY = MOER OXYGEN = INCREASED BOOD FLOW
 produces 3D images showing which parts of the brain are involved when performing a task
EEG
 MEASURES ELECTRICAL ACTIVITY
 4 TYPES OF BRAINWAVE that differ in AMPLITUDE and FREQUENCY (alpha, beta, delta, theta)
 ELECTRODES placed on the SCALP to detect SMALL ELECTRIVAL CHARGES = activity of BRAIN CELLS
 useful for investigating stages of SLEEP and BRAIN ABNORMALITIES such a epilepsy
ERP
 measuring the ELECTRICAL RESPONSE to a SPECIFIC STIMULUS
 shows a stimulus MANY TIMES so that NEURAL ACTIVITY NOT RELATED to the STIMULUS will not occur
CONSISTENTLY – averaged out
 can measure electrical response to a stimulus when a SELF –REPORT may be INACCURATE
POST MORTEM
 AFTER A PERSON DIES to establish the UNDERLYING NEUROBIOLOGY of a particular behaviour
 may study a person that displays INTERESTING BEHAVIOUR when alive
 BROCA’S WORK with TAN in speech production – a large LESION in the BROCA’S AREA
AO3

FRMI: STRENGTHS: DOESN’T RELY on RADIATION – if done correctly it is RISK-FREE, NON-INVASIVE AND
STRAIGHTFOWARD // IMAGES have HIGH SPATIAL RESOLUTION so there is lots of DETAIL and a
CLEARPICTURE of how the brain works

FRMI: WEAKNESSES: EXPENSIVE and there can only be a clear picture if the person stays PERFECTLY
STILL // POOR TEMPORAL RESOLUTION = 5 second LAG between image and initial firing of activity //
CANNOT HOME in on the activity of the individual neurons – DIFFICULT TO BE EXACT of what brain activity
there is

EEG: STRENGTHS: VALUABLE in the diagnosis of conditions like EPILEPSY as well as the understanding of
SLEEP // HIGH TEMPORAL REDUCTION – ACCURATELY detects brain activity VERY QUICKLY

EEG: WEAKNESSES: NOT USEFUL in pinpointing the EXACT SOURCE of NEURAL ACTIVITY // DOESN’T allow
researchers to distinguish between ACTIVITIES or ignoring different but adjacent locations

ERP: STRENGTHS: MORE SPECIFICITY to the MEASUREMENT of processes that EEG CAN’T // excellent
TEMPORAL REDUCTION especially compared to FMRI – widespread measurement // DIFFERENT TYPES of
ERP that allows us to describe the PRECISE ROLE of the cognitive functioning

ERP: WEAKNESSES: LACK OF STANDARISATION in the methodology between different studies – can’t
conform findings // to get PURE DATA, BACKGROUND NOISE and EXTRANEOUS VARIABLE need to be
eliminated = NOT EASY TO ACHIEVE

PM: STRENGTHS: VITAL in providing foundation understanding for KEY PROCESSES E.G WERNICKE + BROCA
// improves MEDICAL KNOWLEDGE and helps generate hypotheses for FURTHER STUDY

PM: WEAKNESSES: OBSERVED DAMAGE to the brain may not be LINKED to the DEFICITS but ANOTHER
UNRELATED TRAUMA or DECAY // RAISES ETHICAL ISSUES – not able to provide INFORMED CONSENT e.g.
HM who lost his ability to FORM MEMORIES

DISCUSS RESEARCH INTO CIRCADIAN RHYTHMS // THE EFFECT OF ENDOGENOUS PACEMAKERS AND EXOGENOUS
ZEITGEBERS ON THE SLEEP/WAKE CYCLE
AO1
CIRCADIAN RHYTHMS
 a type of BIOLOGICAL RHYTHM that lasts 24HRS which regulates a number of different body processes
such as the SLEEP/WAKE CYCLE and the CHANGES in CORE BODY TEMPERATURE
 they begin at about 6 weeks and at 16 weeks the sleep/wake cycle is no longer RANDOM in INFANTS
EXOGENOUS ZEITGEBERS
 EXTERNAL CUES that affect biological rhythms e.g. LIGHT or SOCIAL CUES such as when you have MEALS
ENDOGENOUS PACEMAKERS
 INTERNAL BODY CLOCKS that regulate biological rhythms e.g. SCN
SLEEP/WAKE CYCLE
 LIGHT (the exogenous zeitgeber) ENTERS the RETINA and PHOTORECEPTIVE CELLS and this SENDS
ELECTICAL SIGNALS to the OPTIC NERVE and then to the SCN or the superchiasmatic nucleus (the
endogenous pacemaker), then sends the signal to the PINEAL GLAND which produces MELATONIN that
inhibits the WAKING PART OF THE BRAIN so that you fall ASLEEP
AO3

ANIMAL STUDIES: DE COURSEY made a LESION so the SCN wasn’t CONNECTED IN THE 30 CHIPMUNKS and
then put them back into their NATURAL HABITAT with 2 OTHER CONTROL GROUPS: 24 SURGICAL and 20
INTACT  AFTER 80 DAYS, the lesioned chipmunks had been KILLED by the WEASELS due them not
sleeping

CASE STUDIES ON HUMANS: SIFFRE: spent 7 MONTHS in a CAVE, he was able to have CONTACT with
OTHERS and ADEQUATE FOOD but had NO CUES as to whether it was DAY OR NIGHT, researchers put the
light on when he woke up and off when he went to sleep – they observed and recorded various bodily
functions and sleeping patterns = AT FIRST, the sleep/wake periods were ERRATIC but after time he had A
FREE-RUNNING 25 HOUR sleep/wake cycle = SHOWS THE ENDOGENOUS PACEMAKERS and it would be 24
hours with the ENOGENOUS ZEITGEBERS

METHODOLOGY OF RESARCH: usually are CASE STUDIES with VERY FEW P’S so there may be PARTICIPANT
VARIABLES that are DIFFERENT such as PERSONALITY (wanting to spend time in isolation) = LMITED
GENERALISATIONS e.g. SIFFRE saw that his biological clock at 60 was SLOWER than when he was a YOUNG
MAN BUT A POSITIVE of this is that there has been MANY REPLCATIONS that show 25 hours as well

CARRYING ON ANIMALS FOR HUMANS?: HARDER to GENERALISE the findings to HUMAN BEHAVIOUR AS
HUMANS BRAINS DIFFER to those of animals e.g. a more developed FRONTAL CORTEX and humans have a
CEREBRAL CORTEX AND ETHICAL PROBLEMS: e.g. the chipmunks came to CONSIDERABLE HARM DUE TO
THE LESION BUT does the BENEFIT out way the COST

PRACTICAL APPLICATIONS: BURGESS: exposure to BRIGHT LIGHT before an EAST-WEST FLIGHT DECREASED
the time needed to READJUST to LOCAL TIME – 3 TREATMENTS: CONTINUOUS, INTERMITTENT AND DIM
LIGHT – watch shifted their sleep/wake cycle back over 3 DAYS  CONTINUOUS: rhythm shifted by 2.1
hours , INTERMITTENT: 1.5 hours and DIM: 0.6 hours = CAN COMBAT JET LAG
DISCUSS RESEARCH INTO INFRADIAN RHYTHMS

AO1
INFRADIAN RHYTHMS
 a BIOLOGICAL RHYTHM which occurs LESS than ONE CYCLE in 24 HOURS, such as MENSTRATION and SAD
MENSTRUAL CYCLE
 time between the FIRST DAY of the woman’s period, when the WOMB LINING is SHED, to the day before
her NEXT PERIOD = 28 days approx
 RISING levels of OESTROGEN cause the OVARY to develop an EGG and RELEASE IT (OVULATION)
 after ovulation, PROGESTRONE helps the WOMB LINING to THICKEN, readying the body for PREGNANCY –
if it doesn’t occur, the egg is absorbed into the body, the WOMB LINING SHEDS and leaves the body
(MENSTRUAL FLOW)
MCCLINTOCK
 menstrual cycle = an ENDOGENOUS SYSTEM influenced by EXOGENOUS FACTORS
 showed that a cycle can SYCHRONISE due to FEMALE PHEROMONES
 29 WOMEN with a history of IRREGULAR PERIODS – SAMPLES of PHEROMONES were taken from 9 of
them at DIFFERENT STAGES of the CYCLE with a COTTON PAD on the ARM PIT and worn for 8 HOURS a day
 the pads were treated with ALCOHOL and FROZEN , to be RUBBED on the UPPER LIP of OTHERS
 68% of the women experiences CHANGES to the cycle WHICH BROUGHT THEM CLOSER to the ‘ODOUR
DONORS’
SEASONAL AFFECTIVE DISORDER (SAD)
 seasonal; diagnosed mental disorder in the DSM-5
 SYMPTOMS: LOW MOODS, LACK OF ACTIVITY and INTEREST in life – triggered by the WINTER MONTHS
when the NUMBER of DAYLIGHT HOURS are SHORTER
 INFRADIAN RHYTHM called a CIRCANNUAL RHYTHM – yearly cycle
 could also cause disruption to the SLEEP/WAKE cycle as well
 MELATONIN is seen to be implicated – AT NIGHT, the PINEAL GLAND secretes MELATONIN till dawn when
there is light / in the WINTER, LACK OF LIGHT so the SECRETION PROCESS is LONGER and has a KNOCK-OFF
effect on the PRODUCTION OF SERETONIN (linked with depressive symptoms)
AO3

BASIS OF THE MENSTRUAL CYCLE: MENSTRUAL SYNCHRONY (E.G. MCCLINTOCK) has EVOLUTIONARY
VALUE – ADVANTAGEOUS for FEMALES TO MENSTRUATE TOGETHER and therefore fall pregnant at THE
SAME TIME = NEW BORNS could be cared for COLLECTIVELY within a GROUP = HIGHER SURVIVAL
BUT SCHANK: TOO MANY FEMALES TOGETHER CYCLING would produce COMPETITION for the HIGHEST
QUALITY MALES = AVOIDANCE of SYCHRONY looks like the MOST ADAPTIVE STRATEGY = LOWERS
VALIDITY METHOLOGICAL LIMITATIONS IN SYNCHRONISATION STUDIES: MANY FACTORS may affect CHANGE in the
MENSTRUAL CYCLE e.g. STRESS, CHANGES IN DIET, EXERCISE etc. = CONFOUNDING VARIABLES SO
synchronisations studies like McClintock’s may be likely to be by CHANCE
AND research involves SMALL SAMPLES of women and relies on the SELF-REPORTING of their OWN CYCLE

ANIMAL STUDIES: the role of PHEROMONES in ANIMAL SEXUAL SELECTION is WELL-DOCUMENTED e.g. sea
urchins release pheromones into the water so others would eject their SEX CELLS BUT with HUMAN
BEHAVIOUR, it is SPECULATIVE

PRACTICAL APPLICATION – SAD: PHOTOTHERAPY = a LIGHT BOX that stimulates very strong light in the
MORNING and EVENING to reset MELATONIN LEVELS – in 60% of sufferers it helped BUT recorded a
PLACEBO EFFECT of 30% using a ‘SHAM NEGATIVE-ION GENERATOR
DISCUSS RESEARCH INTO ULTRADIAN RHYTHMS
AO1

ULTRADIAN RHYTHMS
 BIOLOGICAL RHYTHMS that occur MORE THAN ONCE in 24 HOURS such as the STAGES OF SLEEP
STAGES OF SLEEP
 takes place over 90 minutes and include the NREM STAGES (1-4) and the REM STAGE
 STAGE ONE: LIGHT SLEEP (BETWEEN BEING AWAKE and BEING ASLEEP), SMALLER BRAINWAVES, goes from
ALPHA (relaxing/resting) to THETA WAVES (drowsy), lasts for 15 mins
 STAGE TWO: become DISENGAGED from the SURROUNDINGS, BODY TEMP DROPS but BREATHING and
HEART RATE is REGULAR, involves SLEEP SPINDELS and K COMPLEXES, lasts approx 20 mins
 STAGE THREE + FOUR: DEEPEST PART, LOWER BLOOD PRESSURE, SLOWER BREATHING, MUSCLES are
RELAXED, BLOOD SUPPLY to MUSCLES INCREASED, HORMONES (E.G. GROWTH) are RELEASED, TISSUE
GROWTH and REPAIR, ENERGY is RESTORED, DELTA WAVES (sleep/dreaming) and lasts for approx 15 mins
(3) and 40 mins (4)
 REM STAGE: REOCCURS EVERY 90 MINUTES and gets longer in duration as the night continues, provides
ENERGY to the BRAIN and BODY, BRAIN IS ACTIVE and DREAMS OCCUR , EYES MOVE, BODY BECOMES
RELAXED (MUSCLES are ‘turned off’) and has BETA WAVES (active/working)
AO3 EVIDENCE SUPPORTS THE IDEA OF DISTINCT STAGES OF SLEEP: DEMENT + KLEITMAN: monitored SLEEP
PATTERNS of 9 ADULTS in a SLEEP LAB – BRAINWAVE ACTIVITY was recorded on an EEG and the
researchers controlled the effects of ALCOHOL and CAFFINE = REM ACTIVITY HIGHLY CORRELATED with the
experience of DREAMING and activity varied according to how VIVID the dreams were AND WHETHER THE
PPS AWOKEN during dreaming = HIGH ACCURATE RECALL of dreams = REM SLEEP is important INDIVIDUAL DIFFERENCES IN SLEEP STAGES: TUCKER ET AL: p’s studied over 11 DAYS and NIGHTS in
STRICTLY CONTROLLED LAB ENVIRONMENTS – assessed sleep DURATION, TIME to FALL ASLEEP and the
amount of TIME in SLEEP STAGES = INDIVIDUAL DIFFERENCES in stages 3 and 4 which means they may be
BIOLOGICALLY DETERMINED STAGES

LAB SETTING: carried out in a CONTROLLED LAB SETTING only focuses on the BIOLOGICAL DIFFERENCES
BETWEEN PEOPLE = provides support for the role of ULTRADIAN RHYTHMS BUT DON’T examine other
SITUATIONAL FACTORS that may also play a role.

METHODOLOGY: P’S must be are under a SPECIFIC LEVEL of CONTROL and are attached to MONITORS that
measure rhythms - may be INVASIVE = end up sleeping in a way that isn’t the SAME as their ORDINARY
SLEEP CYCLE = extremely difficult to study ultradian rhythms as a LACK OF ECOLOGICAL VALIDITY could
lead to FALSE CONCLUSIONS