Information processing by graded-potential transmission through tonically active synapses.
Many neurons use graded membrane-potential changes, instead of action potentials, to transmit information. Traditional synaptic models feature discontinuous transmitter release by presynaptic action potentials, but this is not true for synapses between graded-potential neurons. In addition to graded and continuous transmitter release, they have multiple active zones, ribbon formations and L-type Ca2+ channels. These differences are probably linked to the high rate of vesicle fusion required for continuous transmitter release. Early stages of sensory systems provide some of the best characterized graded-potential neurons, and recent work on these systems suggests that modification of synaptic transmission by adaptation is a powerful feature of graded synapses.
Juusola
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Dept of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.
French
A S
AS
Uusitalo
R O
RO
Weckström
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M
D000818:Animals; D009474:Neurons / Q000502:physiology* / Q000648:ultrastructure; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*