Exploring retrograde signaling via astrocytes as a mechanism for self repair

Recent work has shown that astrocytes are capable of bidirectional communication with neurons which leads to modulation of synaptic activity. Moreover, indirect signaling pathways of retrograde messengers such as endocannabinoids lead to modulation of synaptic transmission probability. In this paper we hypothesize that this signaling underpins fault tolerance in the brain. In particular, faults manifest themselves in silent or near silent neurons, which is caused by low transmission probability synapses, and the enhancement of the transmission probability of a “faulty” synapse by indirect retrograde feedback is the repair mechanism. Furthermore, based on recent findings we present a model of self repair at the synaptic level, where retrograde signaling via astrocytes increases the probability of neurotransmitter release at damaged or low transmission probability synapses. Although our model is still at the embryo stage, results presented are encouraging and highlight a new research direction on brain-like self repair.