Dopamine, ADHD, and Signal to Noise Ratio

Continued from: “Dopamine and the Traction between Internal and External Time”

Cambridge in Colour
Cambridge in Colour

Dopamine bumps the signal to noise ratio in the brain, increasing pattern recognition, even for things that may not be there, as in paranoid schizophrenia. Dopamine deficit lowers the signal to noise ratio, making the signal difficult to distinguish from the background noise, and patterns harder to detect. With ADHD’s dopamine deficit, following one conversation or train of thought can prove tricky because all conversations or thoughts sound equally loud, making it hard to pick out a continuous stream, instead picking up bits and pieces from several different streams of conversation or thought.

Random firing neurons makeup the background noise in the brain, like all the voices at a party not part of your conversation. The person whose voice you focus in on, ignoring all the others, is the signal amidst the noise. A low signal to noise ratio means distinguishing one’s conversation partner’s voice from the surrounding voices proves difficult; all the voices sound equally loud, making it difficult to determine which voice to follow. When the signal to noise ratio increases however, the background noise fades and your conversation partner’s voice become distinct and easy to follow. Dopamine turns up the volume on the signal as compared to the background noise.

Drugs that stimulate the dopamine system treat the dopamine dearth of ADHD. ADHD treatment stimulants–Ritalin, Adderall, and Vyvance–increase dopamine production, enhancing focus and learning. Ritalin boosts dopamine activity and returns the brain functioning to “normal” levels increasing a person’s level of engagement.[1] Psychiatrist Nora Volkow explains, “…Ritalin also works to suppress ‘background’ firing of neurons not associated with task performance, allowing the brain to transmit a clearer signal.”[2] Dopamine increases the signal to noise ratio in the brain, facilitating pattern recognition both in space and across time. Ritalin’s chemical structure mimics cocaine, while Adderall and Vyvance, both amphetamines, impersonate meth. Similar to these heavier drugs, the dopamine they encourage contributes to their addictive nature and the potential for psychosis with heavy or long-term use.

Focus and attention come easier when one’s brain is not being pulled down multiple pathways. Paying attention, establishes traction between your internal frequencies and the external world, synchronizing with it, using it to help calibrate your internal pace. A brain going in a million different directions, has trouble hanging onto external processes long enough to synchronize with them. Thus, unable to follow a trail outside of oneself, one can get stuck bouncing around inside, making it difficult to learn and follow through.

If attention indicates the synchronization with and thus amplification of time scales, too little or too much dopamine prevents that synchronization, making it difficult to maintain attentiveness or relate to the requirements of the external world. An abundance of dopamine however, reveals copious connections, too many things to pay attention to, too much meaning in mundane events, maybe some that don’t exist. Yet somewhere in the middle lurks a sweet spot of a flow state, where one’s internal traction locks gears with the outside world, where attention engages, memory provides enough predictability, and presence to the living world provides enough surprise, and where the signal to noise ratio is not too subtle, nor too strong. Luckily, a specific relationship between frequencies fits the bill, pink noise.

[1] Coghlan, Andy. 2009. “Time moves too slowly for hyperactive boys.” In New Scientist. June 10,

[2] Brookhaven National Laboratory. 2001. New Brookhaven Lab Study Shows How Ritalin Works. Jan. 16,

This is an excerpt from my forthcoming book “The Texture of Time”



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