The first neurobiological theory I will look at is the activation-synthesis theory. These theory sees dreams as activation in the brain in the areas to do with perception, action and emotion (which occurs during REM). They are essentially random as there is an external blockade (at the top of our spine resulting in paralysis so we cannot act out our dreams) and an internal blockade as only areas of our brain to do with vision and hearing are activated (not to do with taste and smell). This is why dreams can be interpreted as external stimuli and when we wake up it is the brains ‘quest for meaning’ that’s causes us to believe dreams have a meaning. However according to this theory, dreams are simply a bi-product of this neurochemical reaction.
There are a number of drawbacks and advantages of this theory. It explains how we can interpret this signals as being external as neuro-chemicals during dreaming such as seretonin and noradrenalin are low during sleep which also explaing the incoherence of some of our dreams as our attention levels are low. However, as dreams are supposed to be down to ‘random activation’ is does not explain how many dreams can be coherent and relate to our everyday life. A revised version of this theory accepts that some dreams have meanings. This is because during sleep the thoughts of the day are simply re-synthesised.
This theory is based on dreaming during REM, however as dreams also occur during NREM this theory doesn’t explain this. It may be that other areas of the brain during NREM are activated, although further research must be done to assess to overall function of dreams. This theory is deterministic as it believes we cannot control our dreams when this has been shown to be the case during lucid dreams and it is also reductionistic as it ignores the role of psychological factors.