Lecture 13 Dendrites: Function Rachel A. Kaplan and Elbert Heng

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An Overview “Dendrites integrate subthreshold synaptic inputs and ultimately control neuronal output” Again, central thesis of neuroscience: neurons transmit information – Input is input to dendrites – Dendrites by their nature change input – Changed inputs are integrated by soma – Soma then outputs output Information is thus transmitted

Input to dendrite that reaches soma can be affected by... We’ve seen before: LEAKY CABLE STRUCTURE – Length constant – Time constant Both of these have implications for summation of inputs Resultantly: – Relative timing of inputs matters (this lecture doesn’t get into this) – Distance of synapse from soma matters

Solutions to the Leaky Cable Problem Passive properties of dendrites – Morphology adjustments – Large dendrites – Larger EPSPs Active properties of dendrites – Spiking!

PASSIVE PROPERTIES

Morphology The more resistance a dendrite provides, the more of the current and change in voltage will be transmitted farther. – (we learned this with length/time constant) As a result, it’s been shown that larger dendrites are thicker – But diameter can only increase by so much...

Larger Distal Inputs Distal synapses do produce larger distal inputs! – Greater magnitude so decay over distance does not as greatly affect input This is due to greater glutamate receptor density

ACTIVE PROPERTIES