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Start of Part 2 Eric W. Harris, PhD.. Here lies the brain (midine view) National Geographic Magazine, February 2014.

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Presentation on theme: "Start of Part 2 Eric W. Harris, PhD.. Here lies the brain (midine view) National Geographic Magazine, February 2014."— Presentation transcript:

1 Start of Part 2 Eric W. Harris, PhD.

2 Here lies the brain (midine view) National Geographic Magazine, February 2014

3 Gray Matter, White Matter, Gyri, Lobes “White matter” (fiber tracts) “Gray matter” (cell bodies) Gyrus (infolding of cortex) Lobe (major infolding)

4 The Basic Subdivision of Cerebral Cortex

5 Some Functional Subdivisions of the Cerebral Cortex

6 Brodman Areas – the ultimate subdivision?

7

8 Under the hood – some pieces and parts… (connects the hemispheres ) (protect the brain)

9 The functional building block of the brain – the Neuron (“brain cell”) Santiago Ramon y Cajal (1852 – 1934) 4 – 100 microns ( x in., or – in.)

10 Validation for Cajal left: Cajal Legacy Instituto Cajal (CSIC), Madrid | right: Courtesy Thomas Deerink and Mark Ellisman (NCMIR, UCSD) 1906 Nobel Prize in Medicine and Physiology

11 Basic Structure of a Neuron Dendrites Axon ell body ~85 Billion neurons in the human brain

12 Important properties of neurons  Neurons have a negative “membrane potential” (i.e., inside negative vs. outside)  Most neurons have many (thousand) inputs that constantly change this “membrane potential”  Neurons will send a signal if they become sufficiently less negative (more positive, “depolarized”)  This signal starts is a wave of “positivity” that regeneratively propagates down the axon  Neurons can send signals quickly (~100 m/sec) to other neurons, muscles, glands etc.  Compared to other cells, neurons have high energy demands, and low energy reserves.  Neurons do not divide and replace themselves – if damaged enough to die, they are not replaced (with few exceptions).

13 Neuronal “Resting Membrane Potential” Voltage Display

14 Source of the Resting Membrane Potential  Specialized molecules pump ions into and out of the neuron (Na + out, K + in), yielding different concentrations of these ions inside vs. outside of the cell. In effect, the pump creates Na + and K + “batteries”. ( A big part of the energy demand)  Specialized channels allow more or less of these ions to flow in (or out) of the cell, in effect “dialing in” more or less of each “battery”  Other ions also contribute, so it’s not as simple as just Na+ and K+…

15 End of Part 2 See Part 3 for more


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