Serotonin and Dopamine in Consciousness
Claude de Blainville
The Role of Dopamine and Serotonin in the Central Nervous System(C.N.s)
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Serotonin and dopamine play,normally,opposite roles in the CNS:
Serotonin decreases behaviours while dopamine stimulates behaviours.So
serotonin enhances INACTIVITY while dopamine stimulates ACTION.
There is a balance of actions between dopamine and serotonin.This is called
the Dopamine/serotonin balance.There is also a balance of actions between
serotonin itself.For instance,most serotonin actions decrease dopaminergic
activity while,sometimes,serotonin can,paradoxically,enhance dopamine
influence through 5-HT2A receptors for example.
The balance of inhibition and activation of dopamine by serotonin is called
the Serotonin/Serotonin balance.
Effects of Serotonin on Behaviour
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Serotonin controls the quantity of information flow from memory to
consciousness.Increasing serotoninergic activity,for instance through the
specific serotonin reuptake blockers,will decrease the quantity of
information flow from memory to consciousness while decreasing serotoniner-
gic activity through hallucinogens(with the notable exception of 5-HT2A
receptors)will increase information flow from memory to consciousnness.Under a
SSRI consciousness is nearly devoid of thoughts,at certain optimum doses,while
under hallucinogens the opposite happens:consciousness is full of thoughts.The
same holds true with cannabinoids.
Increase in serotonin leads to THYMOANESTHESY which means that serotonin
anesthesises emotions.
Decrease in serotonin(for example through MDMA,MDA,etc)leads to stimulation
of sociability and mood,aggressivity and sexuality,etc,probably by augmenting
dopaminergic activity normally blocked by serotonin(except 5-HT2A receptors)
Here are some effects of serotonin as demonstrated through zimelidine and
fluvoxamine:
I.Decrease in informational flow from memory to consciousness:the quantity
of thoughts per unit of time,under zimelidine or fluvoxamine,reaching
consciousness is diminished as to base-line levels.
2.Motivations are decreased.
3.Emotions are anesthesised
4.Sexual desire is decreased or suppressed
5.Sleep or quasi-sleep is increased
6.Aggression is reduced.
7.Locomotion is diminished
8.Because of (1)obssesive thoughts or suicidal thoughts,etc,are reduced
9.Under fluvoxamine suicidal ideation can be reversed quite fast but not as
spectacularly as with Gamma-hydroxybutyrate.
Contrary to typical serotoninergic reuptake blockers which induce somnolence
fluoxetine is atypical because it induces insomnia.It can also induce
headaches which are reversed by fluvoxamine.Insomnia is also reversed
through fluvoxamine.As also fluoxetine(Prozac)is subhallucinogenic one
concludes that fluoxetine has a differential tendency to indirectly
stimulate 5-HT2A receptors,thus activating dopaminergic activity.
Activation of dopamine neurotransmission leads to insomnia.
Effects of Dopamine on Behaviour
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The effects of dopamine on behaviour can be evaluated with the dopamine
reuptake blockers amineptine and nomifensine(nomifensine has also a
noradrenergic component).
Stimulation of dopamine neurotransmission can induce the following effects:
I.Mental and motor activation.
2.Stimulation of mood WITHOUT concomittant "euphoria".
3.Amineptine can induce a potentiation of benzodiazepines induced
anxiolysis.
4.Some authors say that amineptine can alleviate some schizophrenic sympt-
oms,which is consistent with the hypothesis of hypofrontality linked
to decrease in dopamine neurotransmission.
5.Dopamine seems to be an UBIQUITOUS METABOLIC ACTIVATOR.It thus activates
neuronal systems while serotonin,normally,seem to deactivate neuronal
systems.
6.Dopamine stimulates motivations and lifts undecisiveness.Undecisiveness
gives rise to self-confidence.If dopamine is overactivated then
self-confidence increases to the point of being delusional!
Serotonin and Dopamine in States of Consciousness
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A.Depression
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Serotonin alleviates depression by reducing excessive reaction to exogenous or
endogenous stimuli.Serotonin is an ANTI-STRESS molecule which is very
effective leading,ultimately,to blunting of emotions such as THYMOANESTHESIA.
Thus serotonin seems to be one of the molecule of PLACIDITY,tranquillity,peace
of mind.Maybe adepts of Zen could stimulate their serotoninergic system in
order to attain serenity.
Dopamine alleviates depression by STIMULATING ACTION and lifting
undecision.Dopamine activates blood-flow which may be an important factor in
its anti-depressive action.
Depression is alsolifted in the oneiric state,while metabolic activity in the
CNS is very high.
Depressed people are not depressed anymore in the dream state but become,all
of a sudden,depressed again when they go out of the dream state.This can be
explained in term of metabolism and in the way memory is structured.
B.Schizophrenia
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Serotonin seems to play a role in the blunting of emotions seen in
schizoprenics.
Dopamine HYPOACTIVITY in the frontal cortex is responsible for the negative
symptoms of schizophrenia while HYPERACTIVITY elsewhere is responsible of the
positive symptoms.