TY - GEN A1 - Salmasi, Mehrdad A1 - Loebel, Alex A1 - Glasauer, Stefan A1 - Stemmler, Martin T1 - Short-term synaptic depression can increase the rate of information transfer at a release site T2 - PLoS Computational Biology N2 - The release of neurotransmitters from synapses obeys complex and stochastic dynamics. Depending on the recent history of synaptic activation, many synapses depress the probability of releasing more neurotransmitter, which is known as synaptic depression. Our understanding of how synaptic depression affects the information efficacy, however, is limited. Here we propose a mathematically tractable model of both synchronous spike-evoked release and asynchronous release that permits us to quantify the information conveyed by a synapse. The model transits between discrete states of a communication channel, with the present state depending on many past time steps, emulating the gradual depression and exponential recovery of the synapse. Asynchronous and spontaneous releases play a critical role in shaping the information efficacy of the synapse. We prove that depression can enhance both the information rate and the information rate per unit energy expended, provided that synchronous spike-evoked release depresses less (or recovers faster) than asynchronous release. Furthermore, we explore the theoretical implications of short-term synaptic depression adapting on longer time scales, as part of the phenomenon of metaplasticity. In particular, we show that a synapse can adjust its energy expenditure by changing the dynamics of short-term synaptic depression without affecting the net information conveyed by each successful release. Moreover, the optimal input spike rate is independent of the amplitude or time constant of synaptic depression. We analyze the information efficacy of three types of synapses for which the short-term dynamics of both synchronous and asynchronous release have been experimentally measured. In hippocampal autaptic synapses, the persistence of asynchronous release during depression cannot compensate for the reduction of synchronous release, so that the rate of information transmission declines with synaptic depression. In the calyx of Held, the information rate per release remains constant despite large variations in the measured asynchronous release rate. Lastly, we show that dopamine, by controlling asynchronous release in corticostriatal synapses, increases the synaptic information efficacy in nucleus accumbens. Y1 - 2019 UR - https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1006666 U6 - https://doi.org/10.1371/journal.pcbi.1006666 SN - 1553-7358 SN - 1553-734X VL - 15 ER - TY - GEN A1 - Salmasi, Mehrdad A1 - Stemmler, Martin A1 - Glasauer, Stefan A1 - Loebel, Alex T1 - Synaptic Information Transmission in a Two-State Model of Short-Term Facilitation T2 - Entropy N2 - Action potentials (spikes) can trigger the release of a neurotransmitter at chemical synapses between neurons. Such release is uncertain, as it occurs only with a certain probability. Moreover, synaptic release can occur independently of an action potential (asynchronous release) and depends on the history of synaptic activity. We focus here on short-term synaptic facilitation, in which a sequence of action potentials can temporarily increase the release probability of the synapse. In contrast to the phenomenon of short-term depression, quantifying the information transmission in facilitating synapses remains to be done. We find rigorous lower and upper bounds for the rate of information transmission in a model of synaptic facilitation. We treat the synapse as a two-state binary asymmetric channel, in which the arrival of an action potential shifts the synapse to a facilitated state, while in the absence of a spike, the synapse returns to its baseline state. The information bounds are functions of both the asynchronous and synchronous release parameters. If synchronous release facilitates more than asynchronous release, the mutual information rate increases. In contrast, short-term facilitation degrades information transmission when the synchronous release probability is intrinsically high. As synaptic release is energetically expensive, we exploit the information bounds to determine the energy–information trade-off in facilitating synapses. We show that unlike information rate, the energy-normalized information rate is robust with respect to variations in the strength of facilitation. Y1 - 2019 U6 - https://doi.org/10.3390/e21080756 SN - 1099-4300 VL - 21 IS - 8 ER - TY - GEN A1 - Salmasi, Mehrdad A1 - Glasauer, Stefan A1 - Stemmler, Martin T1 - Short-term facilitation and neurotransmitter spillover counteract each other in neuronal information transmission T2 - 28th Annual Computational Neuroscience Meeting: CNS*2019 Y1 - 2019 UR - https://bmcneurosci.biomedcentral.com/articles/10.1186/s12868-019-0538-0 U6 - https://doi.org/10.1186/s12868-019-0538-0 SN - 1471-2202 SP - 155 EP - 156 ER - TY - GEN A1 - Glasauer, Stefan A1 - Salmasi, Mehrdad A1 - Stemmler, Martin T1 - The synergy between neurotransmitter spillover and asynchronous release in information transmission T2 - Bernstein Conference 2018 Y1 - 2018 U6 - https://doi.org/10.12751/nncn.bc2018.0209 ER - TY - GEN A1 - Salmasi, Mehrdad A1 - Glasauer, Stefan A1 - Stemmler, Martin T1 - Neurotransmitter spillover redresses the information loss caused by synaptic depression T2 - Lisboa 2019, Conference Lisbon, Portugal, 28 feb - 3 mar Y1 - 2019 UR - http://cosyne.org/cosyne19/Cosyne2019_program_book.pdf SP - 154 ER - TY - GEN A1 - Salmasi, Mehrdad A1 - Glasauer, Stefan A1 - Stemmler, Martin T1 - The optimal number of release sites in synapses with neurotransmitter spillover T2 - Bernstein Conference 2019 Y1 - 2019 U6 - https://doi.org/10.12751/nncn.bc2019.0264 ER -