Tools to Enhance Working Memory & Attention
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- ~4 min
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- 29 Jan 2024
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- 1:31:12
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KEYPOINTS
- 01
Working memory is built to discard information, not store it
Short- and long-term memory depend on neuroplasticity: long-term potentiation, long-term depression and, in some cases, neurogenesis. Working memory, as far as anyone knows, does not. It is a circuit running the same algorithm over and over to hold information just long enough to sequence actions, then drop it. Huberman's example is a morning routine: water, coffee, shoes, then deciding your running route.
- 02
Almost every daily task depends on working memory
From waking to sleep, sequencing cognitive and motor steps requires it. People with diminished or (rarely) absent working memory struggle badly to order everyday activities. Deficits in working memory and attention are also hallmarks of frontal traumatic brain injury, Parkinson's, some dementias and ADHD.
- 03
Dopamine sent to the prefrontal cortex sets your working-memory span
Brainstem dopamine neurons project to the prefrontal cortex (the mesocortical pathway). How much dopamine is released there per unit of time strongly predicts whether capacity is low, medium or high. In imaging studies, short spans correlate with less dopamine available for release and longer spans with more.
- 04
Dopamine and working memory follow an inverted U
In bromocriptine studies from Mark D'Esposito's lab at UC Berkeley, low-span people improved substantially after taking the drug, often going from 0–3 remembered words to 4 or even 6. High-span people gained little at low or moderate doses, and at the highest dose their performance dropped to low-span levels even though dopamine availability had risen. More dopamine helps only up to a point.
- 05
Working memory has two separable parts: switching tasks and ignoring distractors
Task and context switching relies largely on dopamine to the basal ganglia, the brain's 'go/no-go' circuitry. Filtering out distractors relies mainly on dopamine to the prefrontal cortex. Studies that selectively boost one pathway improve one ability without the other, so protocols differ in which aspect they help.
- 06
Your baseline score determines whether boosting dopamine is a good idea
Because of the inverted U, Huberman says people with already-high spans probably should not stack dopamine-raising protocols right before working-memory-heavy tasks. Those protocols can still be useful at other times. People with low or moderate spans are the ones most likely to benefit.
- 07
NSDR and yoga nidra can raise baseline dopamine substantially
Yoga nidra ('yoga sleep') is lying down with a script that guides long exhales and muscle relaxation; NSDR is Huberman's term for the version without intentions or mystical language. In one study, baseline dopamine in the basal ganglia was up to 60% higher after an hour-plus session compared with a control protocol. He notes it is a single study and that shorter sessions were not tested.
- 08
Deliberate cold exposure produces long-lasting catecholamine increases
In a study where people sat neck-deep in water in the low 60s °F for 45 minutes or more, epinephrine, norepinephrine and dopamine rose significantly and stayed up for hours. Colder water for a shorter time, such as about 30 seconds at 45 °F, may give a comparably large rise. He prefers these slow-tapering increases to the sharp spikes from video games, sex or chocolate.
- 09
Binaural beats give small-to-moderate working-memory gains
With headphones, each ear hears a different frequency and the difference (for example 40 Hz or 15 Hz) entrains certain circuits. A 2019 study of 24 people aged 19–31 found modest but significant working-memory improvements with 40 Hz beats. A 2016 study using 15 Hz beats linked changes in cortical connectivity to better visuospatial working memory. Whether this works through dopamine is unknown.
EXAMPLES
- 01
The six-sentence span test
Listeners hear six sentences (for example 'some reptiles eat only once a year') and then recall the last word of each: costs/up, summer, cars, year, life, country. Recalling 3–4 is average; 4–6 counts as high span and fewer than three as low span. Getting all six is very rare.
- 02
Letter-string warm-up
Before the sentence test, he reads strings of 5–7 letters (J K Z P I; R O M K L E; W A C Q V D N), repeating each one to make it easier than a lab version. Attention split with driving or chores lowers scores.
- 03
Tyrosine in a multitasking environment (Thomas et al., 1999)
Participants took 150 mg/kg of crystalline L-tyrosine mixed into applesauce, versus placebo, and showed statistically significant but not large working-memory gains while multitasking. For Huberman at about 100 kg, that would be 15 g. He feels a clear lift from 500–1,500 mg and will not recommend the study dose.
- 04
Bromocriptine timing
The dopamine agonist peaks in about 90 minutes, which is when testing was done. It is sometimes prescribed off-label by neurologists for TBI, Parkinson's-related or ADHD-related working-memory deficits, but it is not a standard treatment for those conditions.
OTHER RELEVANT
- 01
Test yourself first, then pick tools
Use the sentence test to estimate your span. Low or moderate scorers can try NSDR or yoga nidra (free scripts, including 10-minute versions and ones by Kelly Boys running from about 8 to 45 minutes), or a cold shower 30–60 minutes before focused work. The cold-shower timing is his mechanistic guess; it has not been tested directly.
- 02
Cold-water safety
Most people use 30 seconds to 3 minutes in a shower, plunge or other body of water. He insists you never combine hyperventilation or breath holds with cold water, because you can pass out and die.
- 03
Supplements: talk to a provider and start with a minimal dose
For L-tyrosine he suggests trying about 250 mg at 50 kg or 500 mg at 75–100 kg, and watching for a crash 3–4 hours later. Mucuna pruriens is essentially L-dopa (about 99%) and potent; studies use 1–5 g, but he suggests starting at 250–500 mg and only with a doctor's approval.
- 04
Prescription stimulants have a place
He believes Adderall and Ritalin (which differ in their dopamine-to-norepinephrine ratio), and modafinil in some cases, are probably over-prescribed but genuinely help some children and adults, partly by enabling plasticity in attention circuits. Behavioral and nutritional tools may allow some people to lower their doses, but any change should be made with a physician.