Extent of Brain Localization

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