Outer Surface of Human Brain

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Outer Surface of Human Brain
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Axial Slice through Human Brain
Gray Matter Neuron cell bodies dendrites
Gyri
Cortex Outer layer of gray matter
Sulci
White Matter Myelin (fat)- covered axons
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Single pyramidal cell in cortex
For brain electrical activity to be detectable
through skull, must be strong signal summed over
many neurons - All behaving similarly at
same time - All oriented in same way - So
negative and positive dont cancel each
other out when summed Pyramidal Cells in
the cortex have the right properties
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Pyramidal Cell Orientation in Cortex
Pyramidal Cells mostly oriented in same
direction relative to cortical surface -
Radially, pointing out toward cortical
surface - Activity from gyri more
detectable at scalp than activity from sulci
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Alpha Waves
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