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1. Computational modeling of long-term depression of synaptic weights: insights from STDP, metaplasticity and spontaneous activity

Creator:
Beňušková , Lubica and Jedlička, Peter
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
LTP, LTD, STDP, metaplasticity, and spontaneous activity
Language:
English
Description:
Using the STDP rule with metaplasticity, we show that to evoke long-term depression (LTD) or depotentiation of synaptic weights in the spiking model of granule cell is not easy. This is in accordance with a number of experimental studies. On the other hand, heterosynaptic LTD which accompanies homosynaptic long-term potentiation (LTP) is induced readily both in the model as well as in experiments. We offer possible explanation of these phenomena from STDP, metaplasticity and spontaneous activity. We suggest conditions under which it would be possible to induce homosynaptic LTD and depotentiation.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2. Modeling the STDP symmetry-to-asymmetry transition in the presence of gabaergic inhibition

Creator:
Cutsuridis , Vassilis, Cobb, Stuart, and graham , Bruce P.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Hippocampus, CA1 pyramidal neuron, computer model, STDP, GABA, LTP, LTD, and calcium
Language:
English
Description:
Experimental studies have shown a symmetry-to-asymmetry transition of the spike-timing dependent plasticity (STDP) curve exists in the proximal stratum radiatum (SR) dendrite of the hippocampal CA1 pyramidal neuron, which is probably due to the presence of GABAergic inhibition [2, 3, 4]. A recent computational model predicted that symmetry-to-asymmetry transition is strongly dependent on the frequency and conductance value of GABA inhibition and that the largest long term potentiation (LTP) value and the two distinct long-term depression (LTD) tails of the symmetrical STDP curve are centred at +10 ms, +40 ms and -10 ms, respectively [8, 9]. In the present paper, we continue to investigate even further via computer simulations the effects of gamma frequency inhibition and its conductance value to the symmetry-to-asymmetry transition of the STDP profile in the SR dendrite and predict that the transition is even more robust when there is a temporal offset between the onsets of the pre-post excitatory stimulation and the GABAergic inhibition. The largest LTP value and the two distinct LTD tails are inversely proportional to the increase of GABA conductance.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public