Regulation of AMPA-type glutamate receptors by phosphorylation is central to the problem of synaptic plasticity at CNS glutamatergic synapses. Our understanding of molecular mechanisms of plasticity critically depends on measurements of the three channel properties – the number of functional receptors in the synapse, their open probability and single-channel conductance – because their product ultimately determines the amplitude of synaptic response and thus the synaptic strength. Two techniques, fluctuation analysis (Katz & Miledy, 1970; Sigworth, 1980; Traynelis et al. 1993) and single-channel recordings (Hamill et al. 1981; Colquhoun & Hawkes, 1995), have been broadly used so far to measure these fundamental parameters. I will describe in my talk a new approach to channel behaviour, silence analysis, which allows assaying these parameters in an alternative way, by analysing the probability of channels to be simultaneously closed (silent). New opportunities brought by silence analysis to the field of ion channels and receptors will be discussed. In particular, silence analysis was applied to the GluR1 AMPA receptor mutated at the S831, the site phosphorylated by calcium-calmodulin-dependent protein kinase II (CaM-KII) during long-term potentiation in the CA1 area of the hippocampus. Results indicate that a negative charge at S831 is a critical determinant for the enhanced channel function of this receptor as a charge carrier. Silence analysis provides independent evidence for the mechanism of AMPA receptor regulation by CaM-KII and further strengthens the idea how calcium-dependent phosphorylation of AMPA receptors can contribute to the plasticity at central glutamatergic synapses.