Neurobiology -: Homeostasis or synaptic plasticity?

Learning and memory are dependent on synaptic plasticity, through long-lasting changes in synaptic strengths. The two well-characterized forms of plasticity are long-term potentiation (LTP) and long-term depression (LTD). But one group has now discovered a completely different form of plasticity. Whereas LTP and LTD modulate the strength of synapses in a synapse-specific manner, the new form represents a more general regulation of the total synaptic strength of a neuron. And because it is bidirectional, it could have interesting computational properties.