Symposium focuses on two major problems: synaptic plasticity with particular emphasis on GABAergic plasticity and information encoding in the neuronal networks interacting with astrocytes (Curreli et al.) and extracellular matrix (Wiera et al.). The first two presentations (Curreli et al., Barberis et al.) from IIT (Italy) are presenting data on information encoding using methodology based on cutting edge optical techniques. Curreli et al. will show new data on encoding spatial information in the hippocampus emphasizing the role of astrocytes whose activity is monitored as calcium signaling. Andrea Barberis will talk about signaling between basolateral amygdala and ventral hippocampus in the context of transmitting by the BLA neurons both positive and negative predicting cues. They suggest that valence-activated BLA neurons contact vCA1 dendrites in a precise spatial organization that together with inhibitory synapses can generate unique valence-related spiking patterns in the postsynaptic neuron. To validate this hypothesis, they built a map of the spatial location of functional synaptic inputs from BLA, vCA3 and bistratified interneurons onto vCA1 pyramidal neurons. They have developed an automated procedure to perform single-spine calcium imaging in the whole vCA1 dendritic arbor exploiting custom made neural network algorithms combined with electrophysiology and optogenetics. This integrated approach allowed them to reveal the unique distribution of BLA and vCA3 and inhibitory inputs onto the whole dendritic arbor of vCA1 pyramidal neurons. The third speech will be given by prof. Dariusz Rakus and the leitmotif of this presentation are novel findings that Inhibition of glycogen phosphorylase (PYG), an enzyme responsible for glycogen breakdown, disrupts LTP induction and memory formation in young animals. However, intriguingly, in aged brains, PYG inhibition enhances LTP and improves cognitive performance. Prof. Rakus will present recent data that this paradoxical effect may relate to elevated lactate concentrations observed in aged brains and in neurodegenerative conditions such as Alzheimer’s disease (AD). In particular, their preliminary data demonstrate a significant increase in expression of the lactate receptor GPR81 (HCAR1) in the CA1 and CA3 hippocampal regions of aged mice, suggesting that excessive lactate signaling could contribute to impaired synaptic plasticity. Altered cross-talk between neurons and astrocytes in aged animals will be emphasized. The last speech will be given by Dr. Grzegorz Wiera (cooperation with Jerzy Mozrzymas) will be dedicated to the phenomenon of co-plasticity which is manifested as distinct plasticity phenomena at inhibitory and excitatory synapses, depending on where the inhibitory input is located on pyramidal neurons (soma, proximal dendrites in the CA1 stratum radiatum, and the distal dendrites in the stratum lacunosum-moleculare). These phenomena was found to be markedly regulated by the extracellular matrix that acts as a gatekeeper, restricting certain forms of inhibitory plasticity – when it is removed, hidden GABAergic plasticity emerges. Furthermore, they showed that maintaining inhibitory long-term potentiation (iLTP) relies on a key transsynaptic interaction between neuroligin-2 and neurexin.