Astroglia-specific contributions to the regulation of synapses, cognition and behaviour.

Astrocytes are heterogeneous population of neural cells with diverse structural, functional and molecular characteristics responsible for homeostasis and protection of the central nervous system (CNS). Unlike neurones, astrocytes do not generate action potentials, but employ fluctuations of cytosolic ions as a substrate for their excitability. Ionic signals are associated with neuronal activity and these signals initiate an array of responses ranging from the activation of plasmalemmal homeostatic transporters to the secretion of numerous signalling molecules including neuromodulators, neurotransmitter precursors, metabolic substrates, trophic factors and cytokines. Thus, astrocytes regulate the synaptic connectivity of the neuronal networks by supporting neurotransmitter metabolism, synaptogenesis, synaptic elimination and synaptic plasticity contributing to cognitive processing including learning, memory, emotions and behaviour. Astroglia-specific regulatory pathways affect the most fundamental properties of neuronal networks from their excitability to synaptic connectivity. Thus, it is the concerted action of glia and neurones, which, by employing distinct mechanisms, produce behavioural outputs of the ultimate control centre that we call the brain.