1. motivation, reward & addiction
Feb 20, 2009

2. ..or why we play the lottery
anticipation, outcome and experience
Breiter et al, 2001

3. what motivates us to eat?
escape from hunger
pleasurable (olfactory) experience
boredom
etc…..

4. drive-states:

5. hypothalamus, limbic system and beyond…
influence of learning and emotion on goal-directed behavior - motivation by pleasure?
Kelley 2004

6. addiction
hijacking of the natural reward processes

7. movie time

8. how do we become addicted?
DEPENDENCE
need for continued exposure to a drug so as to avoid withdrawal symptoms
dependence occurs as a result of adaptive changes in the body (homeostasis?)
“cravings” (induction of a drive-state?)
does dependence = addiction?
(Nestler 1992)

9. simple homeostasis
molecular / cellular models of tolerance & dependence

10. from dependence to addiction
why are some abused drugs not addictive?
is there a common “addiction mechanism”?

11. electrical self-stimulation

12. drugs kill
“a hungry animal often ignored available food in favor of the pleasure of stimulating itself electrically times per hour for 24 consecutive hours”
(Olds 1956)

13. “pleasure centers”

14. DA neurons and reward
VTA
(Schultz et al, 1993)

15. does DA signal reward?
displacement of [11C]raclopride binding by DA release
(Volkow et al, 1997)
PET scan
MP = methylphenidate
“RITALIN”

16. learned associations not so fast……
DA activity is altered by experience

17. prediction errors novelty
VTA DA response is associated with sensory cues
i.e., DA response predicts reward
drive is to correct error
(Schultz et al 1997)