Brain Localization and Anatomy

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Brain Localization and Anatomy

• Topics
• Basic brain structures
• Localization sharing across structures
• Cerebrum and lobes of the brain
• Brain trauma and loss of function
• Brocas Aphasia and Split Brain Syndrome
• Cautions and limitations with localization

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What is Localization?

• Early ideas about localization came from Joseph
  Gall Phrenology
• When an area of the brain is implicated for a
  behaviour or function, this area is said to be
  localized for that function
• Use caution when thinking about localization, as
  nearly all areas are interrelated

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Basic Brain Structures and Evolution

• Evolutionary theories suggest that our brain
  evolved from the inside out
• Thinking in these terms helps to remember what
  some functions of the brain are
• The most basic functions are generally on the
  inside, and are similar across species

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The Story of Steve Callahan(taken from
Surviving the Extremes by Kenneth Kamler, MD

• Steve Callahan survived 2 ½ months on the
  Atlantic ocean through a combination of basic
  and higher-order brain functioning
• Examining the stages of his ordeal paints a good
  picture of how our brain functions at different
  levels depending on the situation

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Stage 1 The near-drowning

• While piloting his 21 foot sailboat across the
  ocean, it collided with a whale, and filed the
  lower cabin with water
• Steves reticular activating system (RAS) alerted
  his pons and medulla of danger, and increased his
  alertness and heart rate

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The Brain Stem

• Pons Sleeping, waking and dreaming
• Medulla breathing and heart rate (involuntary
  functions)

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Stage 1 The near-drowning

• While piloting his 21 foot sailboat across the
  ocean, it collided with a whale, and filed the
  lower cabin with water
• Steves reticular activating system (RAS) alerted
  his pons and medulla of danger, and increased his
  alertness and heart rate
• His Amygdala needed to make an immediate fight
  or flight decision as the cabin filled with water

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The Amygdala Hippocampus

• Amygdala Fight or flight decisions
  emotional control
• Hippocampus Gateway to memory forming of
  new memories, calming the RAS down

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Stage 2 The Return

• Once out of the cabin (and safe in a life boat),
  Steves cerebellum and cerebral cortex alerted
  him that he did not have his survival pack

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The Cerebellum

• Cerebellum Balance, coordination remembering
  simple skills

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Stage 2 The Return

• Once out of the cabin (and safe in a life boat),
  Steves cerebellum and cerebral cortex alerted
  him that he did not have his survival pack
• Temporally suppressing the medullas involuntary
  breathing control, he went back into the cabin
• Resisting the hypothalamuss warnings that he
  needed to breath, he cut the survival pack away
  nearly passing out in the meantime

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The Thalamus Hypothalamus

• Thalamus- Coordination of information to other
  areas
• Hypothalamus Control of hormonal release, basic
  drives for hunger, thirst emotion and sex

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Stage 2 The Return

• Once out of the cabin (and safe in a life boat),
  Steves cerebellum and cerebral cortex alerted
  him that he did not have his survival pack
• Temporally suppressing the medullas involuntary
  breathing control, he went back into the cabin
• Resisting the hypothalamuss warnings that he
  needed to breath, he cut the survival pack away
  nearly passing out in the meantime
• Was able to get the pack before the Hypothalamus
  shut down the cerebral cortex, and sent a message
  to the Medulla to resume normal breathing

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The Cerebrum

• Cerebrum Tightly packed cells on outside of
  brain higher levels of thinking and reasoning

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Stage 3 Survival

• Once the immediate threat was gone, the
  hypothalamus began to send signals that water and
  food were necessary
• Higher order functioning (cerebral cortex) was
  needed to problem-solve how to get food and fresh
  water in the middle of the ocean

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Lobes of the Cortex

• Frontal motor control, speech production
  (Brocas area), short-term memory, emotional
  regulation, complex decision making

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Stage 3 Survival

• Once the immediate threat was gone, the
  hypothalamus began to send signals that water and
  food were necessary
• Higher order functioning (cerebral cortex) was
  needed to problem-solve how to get food and fresh
  water in the middle of the ocean
• The hippocampus began forming new memories of
  things around him which could be used by the
  cerebral cortex to help his situation
• Intensity of Hypothalamus desire for food,
  surpassed the social and emotional regulation of
  the frontal lobe

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Stage 3 Survival

• Now, all lobes of the cerebral cortex responsible
  for survival and rescue

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Lobes of the Cortex

• Occipital Vision

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Lobes of the Cortex

• Parietal Pressure, pain, touch, temperature,
  attention

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Lobes of the Cortex

• Temporal Language comprehension, memory,
  perception, emotion

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Brocas Aphasia

• Named for Dr. Paul Broca, who discovered
  localization of speech production (an area now
  called Brocas area)
• Trauma to this area caused Brocas Aphasia
• Patients could fully comprehend language, but had
  significant difficulty producing spoken and
  (usually) written language
• This clearly showed researchers that speech
  production and speech comprehension were
  controlled in different areas of the brain

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Hemispheric Transfer

• Corpus Callosum The pathway of transfer from
  one hemisphere to another

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Split Brain Syndrome

• Caused when the Corpus Callosum is severed in
  surgery (to treat epilepsy)
• Taught researchers a lot about how our visual
  system processes information in relation to the
  hemispheres
• Lack of communication between hemispheres causes
  weird processing issue in relation to speech and
  motor control
• Video example.

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Cautions about localization

• Although researchers know that certain areas of
  the brain are generally responsible for certain
  functions, this localization is often not
  absolute
• Behaviours usually use multiple areas of the
  brain
• At times, our brains can change localization if
  one area is damaged (especially in children)