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IST8A Fall 2008 Introduction to the Brain

IST8A Fall 2008 Introduction to the Brain. Outline of Topics. Imaging: postmortem and MRI Brain Macro anatomy – lobes, tissues, cortex, hippocampus, amygdala, connectivity Brain Micro anatomy – Neurons Dynamics of brain change over time Our lab: healthy normal aging vs. dementia.

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IST8A Fall 2008 Introduction to the Brain

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  1. IST8AFall 2008Introduction to the Brain

  2. Outline of Topics • Imaging: postmortem and MRI • Brain Macro anatomy – lobes, tissues, cortex, hippocampus, amygdala, connectivity • Brain Micro anatomy – Neurons • Dynamics of brain change over time • Our lab: healthy normal aging vs. dementia

  3. Studies of Brain Form and Function • Postmortem brains Used for precise anatomical measurements • Living subjects (computer analysis) Use MRI imaging to track form and function in living individuals

  4. The Human Brain Cerebrum and Cerebellum -Cerebrum divided into four regions, Frontal, Parietal. Occipital, Temporal -Highly convoluted surface with 6 layers of cells in the cortex.

  5. Four Cerebral Lobes(viewed from midline)

  6. MRI Images • Magnetic ResonanceImaging • Intense magnetic and radio frequency fields • Quantum mechanics • High resolution imaging: 1. anatomical (features in fine detail) 2. functional (activations) • Lauterbur and Mansfield – Nobel Prize 2003

  7. Sample MRI Images • High resolution anatomical MRI • 3D and 2D views • Skull in place and stripped

  8. Coronal Axial (horizontal) Whole Head MRI Slices

  9. Sagittal Whole Head Slice

  10. Macro Anatomy: coronal and sagittal views CSF Amygdala (one on each side) Gray Hippocampus White Tissue Types

  11. Brain Connectivity: Memory Structures External view for context Frontal-occipital fasciculi (axon bundles) hippocampi fornix

  12. An elephant never forgets:comparison of elephant and human hippocampus Elephant hippocampi (red) Human hippocampi Source: www.allmanlab.caltech.edu/PDFs/Hakeem2005.pdf

  13. Brain Connectivity: Visual streams Dorsal and Ventral Incoming Source: The Primary Visual Cortex, by Matthew Schmolesky, http://webvision.med.utah.edu/VisualCortex.html Source: http://philosophy.hku.hk/courses/cogsci/media/visionstreams.jpg

  14. Micro Anatomy: The Neuron Components: • Cell body (gray matter) • Dendrites • Axon (white matter – from myelin sheathes) Axons may be very long e.g. front to back of brain or length of spinal chord Source: www.enchantedlearning.com

  15. Neuron Function Neurons are electrochemical signaling cells. • Signals (action potentials) travel down axons to terminal boutons • Synapse: tiny space between axonal boutons and dendrites of the next neuron • Neurotransmitters: released across synapse by arrival of action potential. Received by post-synaptic dendrites.

  16. Neuron communication Source: http://www.niaaa.nih.gov/Resources/GraphicsGallery/Neuroscience/synapse.htm

  17. Aging and the Brain • What anatomical differences occur between young and old? • What about between healthy normal aging and dementia? • What steps can be taken to minimize or prevent unhealthy changes?

  18. Categories of Aging Very healthy normal Mild cognitive impairment Alzheimer’s Disease

  19. Brain change over 1 year:patterns of gray matter loss Normal Alzheimer’s

  20. Normal vs. Alzheimer’sGross feature differences Coronal view (from front) Two structures illustrated in these slides differ greatly between normal (right) and Alzheimer’s Ventricles (fluid filled cavities) Hippocampi (long-term memory). Left hippocampus in green oval. Alzheimer’s Normal Ventricles greatly enlarged Hippocampi severely shrunken and surrounded by fluid (black spaces) Sagittalview (from side; frontal lobe to left)

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