Shaping excitation at glutamatergic synapses

Glutamatergic synapses vary, exhibiting EPSCs of widely different magnitude s and timecourses. The main contributors to this variability are: presynapt ic factors, including release probability, quantal content and vesicle comp osition; factors that modulate the concentration and longevity of glutamate in the cleft, including diffusion and the actions of glutamate transporter s; and postsynaptic factors, including the types and locations of ionotropi c glutamate receptors, their numbers, and the nature and locations of assoc iated intracellular signalling systems.