• Mayuri Vaish

Acetylcholine and Dopamine: neurotransmitters involved in dreaming

Dreaming is suggested a result of several mechanisms - certain brain wave and brain region activations, as well as, to an extent, neurochemicals such as neurotransmitters.

Theories suggest that dopamine plays a strong role in dreaming. Research has shown that dreaming can be manipulated by dopamine agonists (that stimulate dopaminergic receptors), and through forebrain stimulation (which is dopaminergic - i.e, transmits dopamine). Moreover, forebrain lesions, likely dopaminergic, inhibited dreaming.[1]

Dopamine is produced by dopaminergic neurons within the dopaminergic pathway - including the substantia nigra, ventral tegmental area, and hypothalamus.[2]

Here, tyrosine is converted to L-DOPA by the enzyme tyrosine hydroxylase (TH).[4] This, in fact, is also used to make epinephrine (see below).

Evidence has also indicated that cholinergic receptors (i.e, they respond to the neurotransmitter acetylcholine) contribute to dreams.[5][6][7][8] Specifically, introduction of cholinergic agonists (i.e, molecules that stimulate the acetylcholine receptors) induced dream reports.[9]

Again, acetylcholine is produced by cholinergic neurons in the cholinergic pathway. [10]

Chemically, acetylcholine is produced from choline via the enzyme ChAT (choline acetyltransferase).[12]

In all, it is proposed that a mixture of dopamine and acetylcholine contribute to dreaming.[13][14]

Dreaming has also been linked to lower levels of serotonin.[15] It has also been suggested be due to lowered histamine, and norepinephrine.[16] However, as you have not asked for the absent neurotransmitters, I will not delve into this further.

Just to further briefly describe existing knowledge on how dreams occur: dreaming is known to correlate with Rapid-Eye-Movement (REM) sleep, but has also shown to occur in non-REM sleep. Research has also found decreased activity in posterior cortical regions, increased limbic activity (mediates emotion), while dreaming.[17] Dreaming has also been associated with the parietal and occipital lobes of the brain.[18]

A summary of brain regions more activated and less activated, during REM and NREM sleep respectively, is below.[19]