Understanding the aminergic/cholinergic ratio during wake and sleep is critical to our homeostatic control of behavioral state. For this discussion, aminergic neurotransmitters are modulators and include serotonin (5HT), norepinephrine (NE), and dopamine (DOPA). The cholinergic neurotransmitter is acetylcholine (ACh) and is excitatory. The key general concept here is that aminergics promote focus and attention vs acetylcholine promotes context and building associations.
During active waking, aminergics are high in the morning, early evening, and in non-rapid eye movement (NREM) deep sleep. By contrast, acetylcholine is lower during quiet waking in the evening and high in rapid eye movement (REM) dream sleep. This aminergic/cholinergic reciprocal interaction has been well studied and speaks to understanding circadian rhythm, sleep cycle control, cognitive executive function, learning and memory, and certain neurodegenerative disorders.
In learning and memory, aminergics promote focus on new information. This information is processed for neural encoding in the hippocampus where acetylcholine builds associations and context through projections to the cortex in parallel distributed processing networks.
In test preparation, students reviewing information require more aminergics to focus their attention and recall on previously encoded associations. Students learning information for the first time before a test require both aminergics and cholinergics.
In geriatric cognitive decline, cortical cholinergic neurons are depleted. The behavioral correlate of this is where aging individuals have trouble building associations and contextualizing new information, often being able to only understand one item of information at a time. This dramatically affects decline in working and short-term memory, while essentially keeping previous long-term memories intact.
Late night TV programming is generally entertainment with mostly singular guests and themes, heavily weighted on aminergic focus and attention. Conversely, morning TV programming generally has multiple themes, news, and guests, heavily weighted on more cholinergic context. If the NBC Today Show format were on in the evening during our quiet waking hours, we might be forced to shift our aminergic/cholinergic ratio and disrupt normal sleep inducing behavior along with disfacilitating sleep cycle control.
Admittedly, this is a broad overview of behavioral state control and is intended as an evidence-based first step in understanding the neurochemical balance of the brain.
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