What is neurotransmitters?
Neurotransmitters are chemical messengers that transmit signals across synapses from one neuron to another. They enable all brain function — from basic reflexes to complex thought.
Key Neurotransmitters in ONDA
| Neurotransmitter | Role | ONDA Relevance | |------------------|------|----------------| | Dopamine | Motivation, reward, working memory | Part 8: focus, micro-rewards | | Norepinephrine | Alertness, attention | Part 7–8: cognitive clarity | | Acetylcholine | Attention, learning | Part 8: signal highlighting | | Serotonin | Mood, regulation | Part 1–2: calm, rhythm | | GABA | Inhibition, calm | Part 1–2: parasympathetic |
Depletion and Restoration
Sustained focus depletes neurotransmitters. Ultradian rhythms (90/20-minute cycles) allow timely restoration. Working against these cycles leads to cognitive burnout.
Why do neurotransmitters matter?
Neurotransmitters matter because nearly every signal in the nervous system depends on them, including signals that leave the brain to control the heart, gut, and muscles. Acetylcholine, for example, is the messenger the vagus nerve uses to slow the heartbeat, and it is also what motor nerves release to make skeletal muscles contract.
Their effects depend on the receptor, not only on the chemical. The same neurotransmitter can excite one cell and inhibit another, depending on which receptor subtype that cell carries. This is why many medications work by blocking, mimicking, or prolonging the action of a neurotransmitter at specific receptors rather than simply adding more of it.
How are neurotransmitters measured?
Neurotransmitters are hard to measure directly in living people, so most measurements are indirect. PET imaging with radioactive tracers can estimate receptor availability or release in the brain, and magnetic resonance spectroscopy can estimate glutamate and GABA levels in a region. Blood and urine levels of substances like serotonin or their breakdown products mostly reflect activity in the body, not the brain, and say little about mood or focus. Tests sold to "check your neurotransmitters" from urine are not considered reliable by mainstream medicine.