6.021/Notes/2006-10-18

Electrical properties of cells

 * Information processing
 * code sensory inputs
 * generate outputs
 * computation
 * Graded potential vs action potential
 * Graded: change in input leads to change in output
 * Doesn't have to be linear, just incremental
 * Many inputs cause graded change in potential
 * All cells do graded potentials
 * Action potential
 * Incremental change leads to different response
 * Neurons/electrical cells
 * Properties of action potentials
 * All-or-none
 * threshold
 * refractory
 * absolute refractory period: essentially impossible to generate action potential
 * relative refractory period: requires stronger stimulus (higher threshold)
 * also a period where threshold is lower (more easily excitable)
 * Strength/duration
 * Accomodation
 * with slow enough change, doesn't cause action potential even after it goes above threshold
 * Anode break
 * can trigger action potential by lowering potential for awhile then raising to rest potential
 * decrement-free
 * can't think of neurons as a wire which degrades a signal
 * neurons have decrement-free conduction