Normality (behavior) - Neuronal and Synaptic Normality

Neuronal and Synaptic Normality

Hebbian associative learning and memory maintenance depends on synaptic normalization mechanisms to prevent synaptic runaway. Where synaptic runaway describes overcrowding of dendritic associations, which reduce sensory or behavioural acuteness proportional to the level of synaptic runaway. Synaptic/neuronal normalization refers to synaptic competition, where the prosper of one synapse may weakening the efficacy of other nearby surrounding synapses with redundant neurotransmission.

Animal dendritic density greatly increases throughout waking hours despite intrinsic normalization mechanisms as described as above. The growth rate of synaptic density is not sustained in a cumulative fashion. Without a pruning state, the signal to noise ratio of CNS mechanism would not be able to operate with maximum effectiveness, and learning would be detrimental to animal survival. Neuronal and synaptic normalization mechanisms must operate so positive association feedback loops to not become rampant while constantly processing new environmental information.

Some researchers speculate that the slow oscillation (nREM) cycles of animal sleep constitute an essential ‘re-normalization’ phase. The re-normalization occurs from cortical large amplitude brain rhythm, in the low delta range (0.5–2 Hz), synaptically downscaling the associations from the wakeful learning state. Only the strongest associations survive the pruning from this phase. This allows retention of salient information coding from the previous day, but also allows more cortical space and energy distribution to continue effective learning subsequently after a slow-wave oscillation episode of sleep

Also, organisms tend to have a normal biological developmental pathway as a central nervous system ages and/or learns. Deviations for a species normal development frequently will result in behaviour dysfunction, or death, of that organism.