[week 1 Introduction]

How we understand ‘human mind’ from the brain?

Jaeseung Jeong, Ph.DDepartment of Bio and Brain Engineering,

KAIST

What is going to happen next?

The marshmallow experimenton deferred gratification

• This study was conducted in 1972 by psychologist Walter Mischel of Stanford University.

• A marshmallow was offered to each child. If the child could resist eating the marshmallow for 15 mins, he was promised two instead of one.

• The scientists analyzed how long each child resisted the temptation of eating the marshmallow, and whether or not doing so was correlated with future success.

Follow-up studies of Marshmallow test

• Mischel discovered there existed an unexpected correlation between the results of the marshmallow test, and the suc-cess of the children many years later.

• The first follow-up study, in 1988, showed that "preschool children who delayed gratification longer in the self-im-posed delay paradigm, were described more than 10 years later by their parents as adolescents who were significantly more competent".

• A second follow-up study, in 1990, showed that the ability to delay gratification also correlated with higher SAT scores.

• Failed children: low academic performance. SAT scores are 210 lower than students of success.Big difference in annual income in 30 years

Brain: The most complex system in the universe

How do we explain Marshmallow test results based on brain func-

tions• A 2011 study indicates that the characteristic in Marsh-

mallow test remains with the person for life.

• Additionally, brain imaging showed key differences be-tween the two groups in two areas: the prefrontal cortex (more active in high delayers) and the ventral striatum in Basal Ganglia (an area linked to addictions).

[BJ Casey et al., (August 29, 2011). "From the Cover: Behav-ioral and neural correlates of delay of gratification 40 years later". Proceedings of the National Academy of Sciences 108 (36): 14998–15003.]

What are the differences in behaviors during the experiment

between two groups of children?

Ability of self-control

• Teaching children to pretend that a marshmallow was only a picture helped them resist the treat for much longer.

• “If they imagine a picture, they can wait as if it were a picture.”

• ‘Perception’ is really important for self-control.

What is going to happen next?

SHOP experiment by Brian Knutson et al.

• Knutson and his team have been putting subjects in-side a magnetic resonance imaging scanner.

• This technique is called functional MRI, and it's about watching the brain in action. In an important paper published last year in Neuron, Knutson's team identi-fied by fMRI what he called a “hedonic competition between the immediate pleasure of acquisition and an equally immediate pain of paying.”

Where are more oxygen deliveredin the brain,

activated regionsor

non-activated regions?

The scanner works by measuring the blood oxygen level dependent (or BOLD) signal. When we think, pon-der, evaluate, giddily anticipate or even fret, oxygen-carrying blood flows to particular brain regions doing

the work.

SHOP experiment by Brian Knutson (2007)

The experiment of SHOP

• Subjects were rolled inside the scanner, where they could see a small video screen that dis-played products available for purchase—DVDs, books, games, small electronic devices.

• After a short interval, the price of the product was displayed, and subjects could choose whether to make a purchase.

• The scanner was activated during three distinct times: product presentation, price display and de-cision.

SHOP experiment by Brian Knutson (2007)

Outcomes of SHOP experiment• When the subjects thought about whether they wanted the prod-

uct, the scanner showed that blood flow was increased to an area called the nucleus accumbens (NAcc), an area of the brain partic-ularly receptive to dopamine, a chemical that promotes desire.

• When the subject was evaluating the price, the medial prefrontal cortex (MPFC) became active; that's where humans tend to process value judgments, goals and other “executive function” in-formation.

• In addition, greater activity in an area called the insula, a region associated with unpleasant emotions and the anticipation of loss, was seen in the brains of subjects who decided not to make a purchase.

Era of Mind-reading Technol-ogy

Complex spatiotemporal dynamics in the Brain

Brain is an information processor

iuij

Spike reception: EPSP, summation of EPSPs

Spike reception: EPSP

Threshold Spike emission (Action potential)

threshold -> Spike

EEG recordings

Neuronal Oscillations

• infra-slow: 0.02-0.1 Hz, • slow: 0.1-15 Hz (during slow-wave sleep or anesthesia)– Slow oscillation (0.2-1 Hz), – Delta (1-4 Hz), – Spindle (7-15Hz), – Theta (generated in the limbic system)

• fast: 20-60 Hz, • ultra-fast: 100-600 Hz.

Complex rhythms and oscillations in the brain

Important issues in this lecture

• What is the marshmallow test? What are the difference between the children of success and failure for their atti-tudes and behaviors? What is the interpretation (and im-plications) of the results in terms of neurobiology?

• What is the SHOP experiment of Knutson group? What are the implications of the results in this study?

• What are the principles of fMRI and EEG: how to measure brain activations using these techniques. What are the advantages of the EEG over other neuroimaging meth-ods?