Plasticity in the brain

Different types of plasticity that exist in the brain

• Hebbian/correlation based: STDP: temporal correlation
  
• Homeostatic:
  Synaptic scaling:scale all weights per synapse according to target firing rate
  Intrinsic plasticity: change the excitability of a synapse depending on postsynaptic firing (change the transfer function)
• Short term plasticity:
  The release of neurotrasmitter is influenced by the recent firing history of the presynaptic neuron, on timescale of ms to minutes. In this way the synaptic transmission of dynamic synapses encodes not only the spike but also the history of previous spikes. In computational terms short term plasticity has been shown to implement a temporal filter (high or low-pass / increase or decrease of neurotransmitter release as response to a spike)
• Structural plasticity:
  controversial, creation of new connections based on correlated firing patterns
• Metaplasticity:
  Experience can change the plasticity rules themselves (!), e.g. regulating the balance of excitation and inhibition by altering the threshold for LTD/LTP. However, confusion in the literature on categorization though, needs still research to clarify

Finally: Amazing experiment made famous by Erismann and Kohler in the 1950's demonstrating the adaptability of our brain: http://whatisupright.livejournal.com/