1. Electroencephalography (EEG) is based on synaptic currents http://www.brightmindsinstitute.com/blog/ http://quizlet.com/4239544/cog-sci-chapter-2-flash-cards/ http://www.acm.org/conferences/sac/sac2000/Proceed/FinalPapers/BC-07/ http://apotential.wordpress.com/2012/07/11/the-neurologist-explains-eegs-to-me/ Synaptic currents create a small electrical field along a neuron If neurons are lined up, the electric fields add together. x Using electrodes placed on the scalp and sensitive amplifiers… …one can record “brain waves”!

3. Glial Cells  There are several different types  Oligodendrocytes – make myelin for axons  Astrocytes – help to provide food and “clean up”  Microglia – Undertakers and “Homeland Security”: detect and repel invaders and get rid of the dead  Ependymal cells – BBBarrier & cerebrospinal fluid  Radial glia – play a big role in development (scaffolding and producing neurons)

4. Peripheral vs. Central Nervous System Myelin

5. ~120g, 8 Billion Cells ~1 Billion neurons (~11:1 glia:neurons) ~150g, 85 Billion Cells ~70 Billion neurons (~1:4 glia:neurons) ~1250g, 75 Billion Cells ~16 Billion neurons (~4:1 glia:neurons) ~1500 g, 170 Billion Cells ~86 Billion neurons (~1:1 glia:neurons)

6. Getting a feel for the computing power of the brain 40 Million cells Thousands of connections each

7. Important properties of neurons  Neurons have a negative “membrane potential” (i.e., inside has negative charge compared to outside/CSF)  Neurons receive many signals that constantly change this “membrane potential”  Neurons will send a signal of their own if they become sufficiently “depolarized”  This signal, the Action Potential is a wave of “positivity” that propagates down the axon  Neurons can send signals quickly (~100 m/sec) to other neurons, muscles, glands etc.  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).