Expression of one group of genes maintains one unit of long-term memory in a brain model

In a brain model, a unit of long-term memory is stored in the encoding synapses of a neuron as a presynaptic axonal 'on-off' pattern through the establishment of long-term potentiation (LTP) and long-term depression (LTD). Repetitive activation of one presynaptic axonal 'on-off' pattern speeds up the subsequent re-activation of the same pattern by inducing expression of a corresponding group of genes in support of the enzymes, protein substrates, and second messengers for the LTP and LTD that encode the unit of long-term memory. Phantom limb pains are memorized and re-activated through the expression of the corresponding group of genes, and re-experiencing the stressful event in post traumatic stress syndrome results from the expression of another group of genes. The sense of requiring less time to experience the content of a successfully retrieved long-term memory reflects an increased speed of re-activating the presynaptic axonal 'on-off' patterns of the memory, or an increased speed of thinking. Giving rise to a sense of familiarity with new things, déjà vu may also be a mental state with increased speed of thinking. The speed of thinking may be decreased in jamais vu that is opposite to déjà vu. Progressive increases in the speed of thinking when engaging in a hobby may open up a previously unused neural pathway that turns a previously happy feeling into an aversive one.