Brain Organization:

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Brain Organization

• Pieces of the Nervous System

julia hamstra April 7, 2006
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Brain Development

• Subdivided into 5 main regions
• Telencephalon
• Diencephalon
• Mesencephalon
• Metencephalon
• Myelencephalon
• encephalon brain

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Brain Development

• Fate of embryonic divisions
• colors match to previous slide

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Ventricles

• Brain contains an interconnected system of
  ventricles

Ventricle animation
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Maters
Brain contains a protective covering
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Corpus Callosum

• Brain is composed of two hemispheres connected by
  a set of fibers (corpus callosum)

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Lobes

• Cortex is subdivided into four major external
  lobes (plus the internal limbic lobe)

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Limbic Lobe

• Found only in the medial view of the brain.
• Its major responsibilities include olfaction and
  emotions

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Specialization

• Some areas of cortex
• (primarily sensory
• and motor areas) are
• topographically
• mapped.
• V1 (retinotopic)
• A1 (tonotopic)
• M1 (mototopic)
• S1 (somatotopic)

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Specialization
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Cortex

• Cortex is layers of cells
• Cerebral cortex
• Cerebellar cortex
• Hippocampus

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Nucleus

• Nucleus is a cluster of cells
• Amygdala
• Caudate
• Pons

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The Electric Brain

• Part 1 Within the cell

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Electrical Brain

• Electrical signals are the form of communication
  for neurons
• Electricity in conducted through and between
  neurons
• What is special about neurons that allows them to
  conduct currents?

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Chemical and Electric Gradients

• Chemical flow of a molecule runs from higher to
  lower concentrations
• Electric flow of ionic molecules toward opposite
  potential
• Gradients are created by cellular membranes
• Gradients will balance to lower energy state

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Ions of the Membrane Potential

• Membrane potential is the difference in voltage
  across it (-70 mv in most neurons)
• Ionic flow creates the membrane potential
• Na
• K
• Cl-

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Ionic Flow

• Leaky Channels
• Any small ions
• Voltage-gated Channels
• Na, K, Ca2
• ATPase Pumps
• Na, K

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Passive and active ionic flow establishes and
maintains resting membrane potential
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Electrical Brain

• Electrical signals are the form of communication
  for neurons
• Electricity in conducted through and between
  neurons
• What is special about neurons that allows them to
  be sensitive to electricity?
• Membrane is specialized for controlled ionic flow
• Then how are signals conducted from the dendrite
  to the terminal boutons?
• To be answered next week