To consolidate or not to consolidate: What are the questions?

This chapter provides a critical review of the term consolidation, which refers to the processes occurring at the level of the neuron and the synapse during and after memory formation or its neural models. Many of the examples discussed here concern artificially induced neural plasticity, such as hippocampal long-term potentiation (LTP) that involves long-term changes in synaptic efficacy as a result of brief high-frequency stimulation of presynaptic, afferent fibers. Interestingly, LTP induction is dependent on simultaneous depolarization of the postsynaptic cell and the activation of postsynaptic receptors by presynaptic inputs. Thus, LTP appears to fit the Hebbian scheme of neuronal plasticity rather nicely, which is one reason for its popularity as a model for memory. Recent evidence shows that the induction of LTP in rats can be blocked completely pharmacologically, without an effect on spatial learning. These findings cast doubt on the relationship between LTP and learning and memory.