The Localization of Function of the Brain

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The Localization of Function of the Brain

• The IB syllabus says Explain One Study Related
  to Localization of Function of the Brain

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In IB speak This means
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The structure and function of the brain

• The brain is the seat of awareness and reason,
  where learning, memory and awareness are centered
• It decides whether decisions were right or wrong,
  and imagines how things might have turned out if
  we had acted differently
• The crowning glory of millions of years of
  evolution as new structures evolve, older
  structures are retained.
• 
  

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Brain Structures

1. Hindbrain
2. Midbrain
3. Forebrain
4. Cerebral Cortex (part or forebrain)

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The Limbic System
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Hindbrain

• Structures on top of our spinal cord.
• Controls basic biological structures.

The brain in purple makes up the hindbrain.
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Medulla Oblongata

• Located just above the spinal cord.
• Involved in control of
• blood pressure
• heart rate
• breathing.

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Pons

• Located just above the medulla.
• Connects hindbrain with midbrain and forebrain.
• Involved in facial expressions.

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Cerebellum

• Bottom rear of the brain.
• Means little brain
• Coordinates fine muscle movements.

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Cerebellum
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Midbrain
If stimulated

• Coordinates simple movements with sensory
  information.
• Most important structure in Midbrain is the
  Reticular Formation controls arousal and ability
  to focus our attention.

If Destroyed
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Forebrain

• What makes us human.
• Largest part of the brain.
• Made up of the Thalamus, Limbic System and
  Cerebral Cortex.

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Thalamus

• Switchboard of the brain.
• Receives sensory signals from the spinal cord and
  sends them to other parts of the forebrain.
• Every sense except smell.

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The Limbic System
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Hypothalamus

• Maybe most important structure in the brain.
• Controls and regulates
• Body temperature
• Sexual Arousal
• Hunger
• Thirst
• Endocrine System

The most powerful structure in the brain.
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Hippocampus

• Involved in the processing and storage of
  memories.

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Amygdala

• Involved in how we process memory.
• More involved in volatile emotions like anger.

The emotion of anger has not changed much
throughout evolution.
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The Cerebral Cortex

• Made up of densely packed neurons we call gray
  matter
• Glial Cells support brain cells.
• Wrinkles are called fissures.
• If you lay brain out it would be as big as a
  large Pizza 2000 pizza.

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The lobes of the cerebral cortex

• Anatomy and function
• http//www.youtube.com/watch?vHVGlfcP3ATI

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The Cerebral Cortex is made up of four Lobes.
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The Lobes of the Cerebral Cortex

• The Occipital Lobe Receives and processes
  visual information. Damage to this area can
  produce blindness, even though the eyes and their
  neural connections to the brain are healthy and
  intact
• The Temporal Lobe Plays an important role in
  complex visual tasks such as recognizing faces.
  Information is also processed from the ears and
  it contributes to balance and equilibrium and
  regulates emotions and motivations such as
  anxiety, pleasure and anger. The left temporal
  lobe is responsible for language and speech.
• The Parietal Lobe receives sensory information
  from all over the body, from sense receptors in
  the skin (e.g. pain receptors), muscles, joints
  and taste buds.
• The Frontal Lobe accounts for about half of the
  volume of the brain, and is the most mysterious
  part of the brain, it receives, integrates and
  processes information about what is going on in
  the other parts of the brain.
• Its been called the executive control centre
  for the brain.
• It is also involved in problem solving tasks.
• The prefrontal cortex is involved in behaviors we
  associate with personality, such as motivation,
  persistence and character we know this from the
  case of Gage 1848.
• Biopsychologists support this with research
  hundreds of years later- damage to this area
  leads to changes personality people who have
  this area damaged, tend to accumulate debts,
  betray their spouses, and abandon friends and
  lose their jobs.

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Frontal Lobes

• Abstract thought and emotional control.
• Contains Motor Cortex sends signals to our body
  controlling muscle movements.
• Contains Brocas Area responsible for
  controlling muscles that produce speech.
• Damage to Brocas Area is called Brocas Aphasia
  unable to make movements to talk.

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Parietal Lobes

• Contain Sensory Cortex receives incoming touch
  sensations from rest of the body.
• Most of the Parietal Lobes are made up of
  Association Areas.

Where would this girl feel the most pain from her
sunburn?
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Occipital Lobes

• Deals with vision.
• Contains Visual Cortex interprets messages from
  our eyes into images we can understand.

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Temporal Lobes

• Process sound sensed by our ears.
• Interpreted in Auditory Cortex.
• NOT LATERALIZED.
• Contains Wernike's Area interprets written and
  spoken speech.
• Wernike's Aphasia unable to understand language
  the syntax and grammar jumbled.

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Association Areas

• Any area not associated with receiving sensory
  information or coordinating muscle movements.

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Motor and Sensory Cortexes
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Specialization and Integration in Language
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Brain Activity when Hearing, Seeing, and Speaking
Words
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Link the following the correct areas of the brain

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The Lobes of the Cerebral Cortex Questions

• What are the functions of the Occipital Lobe?
  What does damage to this area result in?
• What are the functions of the Temporal Lobe? What
  emotions does this area regulate?
• What are the functions of The Parietal Lobe?
• What are the functions of The Frontal Lobes?
• What has the frontal lobe also been called?
• What does the prefrontal cortex do? How do we
  know this?
• How does damage to the prefrontal cortex
  influence a persons personality?

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Looking at the brain..

• Clive Wearing
• http//www.youtube.com/watch?vLu9UY8Zqg-Qfeature
  related
• Mouse song
• http//www.youtube.com/watch?vLi5nMsXg1Lk
• Rap
• http//www.youtube.com/watch?vgWGpCstFn-c
• Einsteins brain
• http//www.youtube.com/watch?vJNOKT-xv7Dw

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Split Brain Studies and Hemispheric specialization
The IB syllabus says Explain One Study Related
to Localization of Function of the Brain
Gazzaniga (1984)
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The Corpus Callosum
Divides the 2 hemispheres.
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The localized functions of the two
cerebral hemispheres
Right
Left
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? Each hemisphere responsible for the opposite
side of the body.
? Left hemisphere receives information from right
field of view and vice versa
? Work with split brain patients helped to
identify differences in function of the two
hemispheres of the brain.
? Hemispheric specialisation also linked with
handedness, in that right handed people have
a dominant left hemisphere and so on.
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Hemispheres

• Divided into to hemispheres.
• Contralateral control right controls left and
  vice versa.
• In general,
• Left Hemisphere logic and sequential tasks.
• Right Hemisphere spatial and creative tasks.

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Split Brain Patients
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Testing the Divided Brain
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Hemispheric Specialization the whole mind

• Our experience of the world, our thoughts and
  feelings seem unitary we have a single
  consciousness
• The brain consists of two symmetrical halves or
  hemispheres and they are joined by the corpus
  callosum
• Each hemisphere is responsible for the opposite
  side of the body
• Therefore if consciousness is associated with the
  brain then the nature of experience and awareness
  is based on the integration of the two
  hemispheres

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Roger Sperrys Gazzanigas Split Brain Research

• In the 1950s Roger Sperry trialed split brain
  operations with monkeys and cats by cutting the
  corpus callosum
• Cutting the corpus callosum seemed to show no
  major effects on behavior (but animals dont have
  language)
• In 1953 one of Sperrys students Mayers invented
  the split brain procedure which lead to one of
  Sperrys most important findings

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Roger Sperrys Gazzanigas Split Brain Research

• In the 1950s Roger Sperry trialed split brain
  operations with monkeys and cats by cutting the
  corpus callosum
• Cutting the corpus callosum seemed to show no
  major effects on behavior (but animals dont have
  language)
• In 1953 one of Sperrys students Mayers invented
  the split brain procedure which lead to one of
  Sperrys most important findings

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Roger Sperrys Roger Sperrys Gazzanigas Split
Brain Research

• The Neurosurgeon Philip Vogel Pioneered a radical
  approach to the treating of severe cases of
  epilepsy (where anti-seizure drugs didnt work),
  by severing the corpus callosum.
• Epilepsy is a common neurological disorder that
  is characterized by recurrent unprovoked
  seizures. These seizures are due to abnormal,
  excessive neuronal activity in the brain
• Split brain surgery was carried out to reduce the
  risk accidental physical injury by reducing the
  severity and violence of epileptic seizures by
  stopping the seizures from spreading from one
  half of the brain to the other
• The treatment worked, and patients seemed
  remarkably normal after the operation.

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Summary reading on split brain experiments
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Roger Sperrys Split Brain Research

• However, the patients studied by Sperry seemed to
  have two independent streams of consciousness
• The appeared to have Two minds functioning
  separately from each other
• Sperry (1968) reported
• In other words, each hemisphere seems to have
  its own separate and private sensations its own
  perceptions its own concepts and its own
  impulses to act, with related volitional,
  cognitive and learning experiences

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Visual information Is processed In the opposite
side Of the brain
creativity, imagination
Right Brain
Left Brain
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Gazzaniga (1984) Split brain observations (A
natural experiment)
Activity See Video

• Aim To investigate hemispheric specialization
  with split brain patients
• Procedure The split brain patient Joe was
  asked to look at a screen with a dot in the
  middle of a computer screen and then name/draw
  the objects he saw as they flashed up on either
  side or both sides of the screen.
• Findings
• When Joe focuses on a point (right visual field)
  everything to the right of the point goes to
  his left brain, the area associated with language
  and speech When a word or picture is flashed on
  the right side, Joe is easily able to name it.
• Information to the left of the point (left visual
  field) goes to the right hand side of his brain
  Joe is unable to name the object, but he is able
  to draw the object with his left hand (which is
  controlled by the right half of his brain)
• Conclusions
• The different hemispheres have separate functions
  (left - language/ right - spatial tasks) - The
  mind is made up of several independent agents and
  they can carry out activities outside of our
  conscious awareness, and they are integrated at
  one point, which Gazzaniga believes is the in the
  left hemisphere
• Criticisms It was a natural experiment so there
  was a lack of control over variables the
  participants mental abilities may have been
  atypical before the operation. There are also
  theoretical problems more recent research has
  reveled differences between left and right handed
  people this research was carried out on a right
  handed participant.

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Why are split brain studies so important?

• They tell us about hemispheric specialization
  (the two hemispheres differ in their functions -
  there are localized functions to each hemisphere)
• When the corpus callosum is severed each
  hemisphere is shown to process information
  without awareness of the other side
• However, split brains are not totally split, and
  lower structures in the brain remain connected,
  such as the limbic system
• Recent split brain operations only cut ¾ of the
  corpus callosum.

Ultimately the left brain tries to explain what
the right brain is doing
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• This research has given us a better understanding
  of how the hemisphere functions interact and
  helped those suffering from severe epilepsy, as
  well as the localized functions of each
  hemisphere
• Gender differences
• Evidence suggests that men and women's brains are
  organized and process information slightly
  differently
• Women have a larger corpus callosum relative to
  the total brain size meaning better communication
  between the hemispheres
• Women have a greater density of neurons in the
  temporal cortex and tend to be better at tasks
  involving language and speaking
• Men tend to have superior abilities at spatial
  tasks (right brain)
• (Glassman, 1998)
• Cerebral dominance
• There is a tenancy for one hemisphere to dominate
  are you a left brain or right brain type of
  person?

Evaluation
Why are split brain studies so important?
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Split Brain Studies and consciousness

• Consciousness awareness of mental events,
  thoughts, motives, perceptions and feeling,
• These are available to consciousness based on
  where we focus our attention
• Sperry and Gazzaniga Believe that consciousness
  is not localized, it is an emergent property
  (it emerges from the brain working as a whole. It
  is a synchronized activity across many areas of
  the brain)
• The brain and nervous system work together in
  forming consciousness
• Clear answers remain elusive are research
  continues

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Task

• Compete key study sheet on Gazzanigas research
• Summarize what split brain research tells us
  about consciousness

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Discussion points

• What does hemispheric specialization mean?
• Give examples of localized functions of the left
  and right brain
• How does split brain research give us insight
  into the workings of the human brain
• Describe the gender differences in brain
  structures
• What does cerebral dominance mean?

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Connecting research to the general learning
outcomes

• For the Biological LOA, there are a number of
  general learning outcomes
• It is important that you are able to match up
  what we have studied with these
• The aim of this activity is to help you to meet
  these general learning outcomes

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Brain Plasticity

• The idea that the brain, when damaged, will
  attempt to find news ways to reroute messages.
• Childrens brains are more plastic than adults.

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The brain is hugely integrated

• There are many different brain areas involved in
  abilities such as vision.
• Maunsell Newsome(1987) proposed there were 19
  visual areas in macaque monkeys. Research needs
  to focus on how the different areas of the brain
  interact together.
• Researchers such as Lashley (1929) believe in
  holism Lashley destroyed virtually all parts of
  rat brains in varying amounts to find the
  location of memory, he concluded that there was a
  law of mass action applied memory loss is
  related to the amount of damage inflicted on the
  rats brain, not the location of the damage.
• We must consider the brain to be a very dynamic
  system

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The Brain Shows Plasticity

• The brain is very flexible and can physically
  adjust the location of function if brain damage
  occurs (e.g. children with damage to their left
  cerebral hemisphere are able to recover their
  language abilities)

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Neural Plasticity

• Neural plasticity is the ability of the brain to
  change structurally and chemically by experience.
  
• Rosenzwigs (1984) experiment with rats showed
  that enriched environments larger neurons in
  the rats so the brain is organized as a result
  of experience.
• Neurogensis is growth of new brain cells.

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Localization is not always clear cut

• Hemispheric asymmetry- there are many variations
  in localization of function between male and
  females and left and right handed participants.
  The findings of studies are usually based on
  right handed males (gender bias)
• Male/ female brain
• http//www.youtube.com/watch?vxxtUH_bHBxs

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Rosenzweigs (1984) study of neural plasticity

• Aim To examine the effect of environment on
  neuronal development
• Procedure Laboratory experiment
• IV environment of the rats (enriched/
  impoverished)
• DV Neuronal development in post mortem
• Findings Enriched environment larger neurons
  with more synaptic connections
• Conclusion The environment can influence neurons
  neural plasticity
• Criticisms Ethics? Does it apply to humans?

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Activity complete a key study sheet on this study
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Quick Quiz answer in pairs

• Give three localized functions of brain
  structures
• What were the aims, procedures and findings of
  Rosenzweigs (1984) study of neural plasticity?
• Using research evidence to support your points,
  give three evaluative points that relate to
  localization of function (you can also bring in
  reductionism here)
• What method did Sperry Gazzaniga use in their
  early research into hemispheric specialization
  with primates?
• What method did Gazzaniga (1984) use to find out
  about the functions of the two hemispheres of the
  brain with Joe?
• What were the findings of Gazzanigas split brain
  studies with Joe?

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• Explain One Study Related to Localization of
  Function of the Brain

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An evaluation of localization of function
(neural plasticity)
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Essential Questions

• What are the localized functions of brain
  structures?
• How can the principles that define the Biological
  LOA be demonstrated in research
• How and why are particular research methods used
  in the biological LOA

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General learning outcomes key study focus
workshop

• We have looked at a number of studies from the
  biological level of analysis
• Phineas Gage (Harlow, 1868) (case study
  qualitative)
• Broca (1861) (case study/ observation -
  qualitative)
• Gazzaniga (1984) (natural experiment -
  quantitative)
• Rosenzweig (1984) (laboratory experiment -
  quantitative)
• Look back at your notes (methodology/principles
  of the Bio LOA), and take notes on butcher paper
  on the following, each group will then present to
  the class
• Explain how the principles of the biological
  level of analysis are demonstrated in that
  research
• Explain research method used give reasons why
  the method was used
• Evaluate that method (strengths weaknesses)
• Discuss ethical considerations relating to the
  research

One scribe in each group should write this up
Post on the wiki