Sleeping on a Problem Where Insight is Expected

Sleeping on a Problem: Where Insight is Expected Robert Stickgold Harvard Medical School Beth Israel Deaconess Medical Center Boston, MA

Insight “The sudden appearance in conscious awareness of a really big new relationship among previously new and useful relationship among previously known information” Questions: How does the nonconscious brain find these relationships? How does it identify them as valuable? How does it bring them into conscious awareness? Should we only consider the “really big” ones?

“Really Big? ” Normal science: "Curiosity demands that we ask questions, that we try to put things together and try to understand [them]. . . In this way we try gradually to analyze all things, to put together things which at first sight look different, with the hope that we may be able to reduce the number of ‘different things’ and thereby understand them better. ” Richard Feynman (1963) "The Feynman lectures on physics"

“Really Big? ” ”Scientific revolutions are inaugurated by a growing sense. . . that an existing paradigm has ceased to function adequately in the exploration of. . . nature. ” Entrenchment reduces possibility of shifting Thomas Kuhn (1962) "The Structure of Scientific Revolutions"

Or Not So Big? Piaget proposed that children learn by constructing a model of the world built of “schemas” that explain how parts of the world work. Assimilation (like normal science) integrates new perceptual information into innate or personally developed schemas (“robins”) (Children are biased to fit data into schemas) (Piaget, 1981)

Or Not So Big? When assimilation fails (“penguins”) accommodation modifies the schemas “to fit reality” (Piaget & Inhelder, 1969, p. 6) So, big or small, the process of insight is probably fundamentally the same.

Sleep & Insight, then, whether related to large or small discoveries, is a special case of Piagetian accommodation in which the process occurs outside of conscious awareness. Obviously, this process of accommodation (and insight) is defined by the innate wiring and functional plasticity of the human brain. The processes of brain plasticity necessary for Piagetian accommodation, and hence for insight, may be most daringly activated, not during wake, but during sleep.

There are Different Kinds of Sleep

A Good Night’s Sleep Wake I/REM sleep Sleep onset II III Stage 2 NREM IV SWS 11 PM 1 AM 3 AM 5 AM 7 AM

Sleep Physiology EEG Wake Stage 2 Stage 4 REM 2 sec EOG Stage 1 Stage 2 REM EMG Wake Stage 4 REM

Neuromodulation Varies Across the Wake-Sleep Cycle Active Wake Quiet Wake SWS REM ACh NE 5 -HT Ach: acetylcholine (scopolamine, belladonna) NE: norepinephrine (MAO inhibitors, cocaine) 5 HT: serotonin (Prozac, LSD)

Regional Activation in REM Sleep

Hippocampal-Neocortical Dialog Neocortex Hippocampus

There are Different Kinds of Memory

Sleep Alters Associative Memory Systems Semantic Priming paper wrong (600 ms) thief wrong (580 ms) right wrong (560 ms) • • Cindi Rittenhouse Jen Holmes Beth Schirmer Lauri Scott

Weak 30 Strong msec 20 10 0 0. 01 0. 17 0. 01 PM NREM

Sleep Enhances Insight Number Reduction Task 1 1 4 9 9 1 4 4 9 4 4 1 9 • Ulrich Wagner • Jan Born Wagner et al. (2004) Nature 427: 352

Development of Insight 1 1 4 9 9 1 4 4 9 4 4 1 9 Solvers Non-solvers 40% 0% Wake/ Day Wake/ Night Sleep/ Night 200 100 SWS 20% Improvement in speed (ms) SWS Subjects gaining insight 60% 0

Sleep Calculates the Rules • Ina Djonlagic • Andy Rosenfeld • Mark Gluck

Probabilistic Learning Card 1 Card 4 80% Card 2 60% Card 3 40% 20% ? !?

Practice & Sleep Enhance Performance Improvement (% of trials) p = 0. 01 Wake 14 Sleep 12 p = 0. 06 10 8 6 4 2 0 Observation Feedback

Weather Forecasting & REM Sleep r = 0. 70 p = 0. 008 REM Sleep (%) 25% 23% 21% 19% 17% 15% 55 65 75 85 Post-Training Performance (% of optimal) 95

Sleep Enhances the Gist Word Lists Door Glass Pane Shade House Ledge Open Breeze Frame Curtain View • Jessica Payne • Ruth Propper • Daniel Schacter

12 -Hour Deterioration % Change (relative to 20 min 15 Sleep Wake 0 -15 -30 * -45 -60 * Studied words Critical lures

Words Recalled Morning Recall r = -0. 47 p = 0. 03 35 25 15 5 10 15 20 SWS (%) 25

Morning & Nap Recall Overnight 50 r = -0. 47 p = 0. 03 30 20 40 30 20 10 0 40 r = -0. 54 p = 0. 037 50 words 40 Nap 60 10 60 80 100 SWS (min) 120 0 0 10 20 30 SWS (min) 40 50

Creative Intrusions Word List Blood Doctor Plate Cup Spoon Cup Fuzzy Rough? Smooth? Swirl Soft? Mountain? ?

Percent of Intrusions Creative Intrusions 40% 20% 0% Wake Sleep

New Experiences are Replayed at Sleep Onset Hypnagogic dreams • Erin Wamsley • Karen Emberger • Laura Babkes

Alpine Racer II • • • 14 out of 16 players (88%) 42% of first night reports contain skiing imagery 3 out of 3 controls who only watched

Alpine Racer Images “I keep seeing all the places where I fall- like, hit the walls. It’s kind of annoying; and then my legs fly up in the air. ” (SEC) “I can sort of feel the motions of the game but more not really seeing it. ” (MLC) “I envisioned myself skiing, and for a second there it felt like I was skiing backwards - something I used to attempt when I was younger. ” (CMD)

Delayed Onset Reporting Standard protocol } REPORTS 0 1 2 3 4 5 6 7 8 } REPORTS Delayed onset 0 1 2 3 Math problems

Insights Without Insight "I felt as though I was falling downhill. And I was dreaming about like instructions to a young king or something. " (JAV, rpt 4) "I felt like I was sort of sliding downhill again. And, um. . . there were instructions and a person and uh, I don't know. " (JAV, rpt 6) "I was having a rather vivid image as though I was moving forward through some kind of a forest. . . I was moving forward very stiffly. Um, my entire upper body was incredibly straight. . . it felt almost as if I was moving forward on a conveyor belt, and, without my legs actually moving. " (MAM, rpt 8)

The Biology of Insight The discovery of “insights” is aided by: • • • Shutting down logical (DLPFC) processing Shutting down episodic memory replay (HC) Enhancing error detection (ACC, MOFC) Enhancing weak associations, and thereby … Enhancing the recognition of accommodations that expand our understanding of the world

The Biology of Insight All of which occurs during REM Sleep! Thus sleep, and REM sleep in particular, may not only represent a model system for the processes involved in insight … But may actually represent a brain state which evolved, in part, to facilitate the discovery of insights.