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Chapter 16: Motivation (Diffuse modulatory systems: NE, serotonin (5-HT),…

- - - - glycogen in liver and skeletal muscle
      - triglycerides in adipose tissue (fat)
  - - - normal
        
        intake = expenditure
      - obesity
        
        intake > expenditure
      - starvation
        
        intake < expenditure
    - - period of starvation
        
        animal with restricted diet will lose body fat
        
        once free access to food is restored, animal will OVEREAT until body fat is restored
      - period of forced feeding
        
        animals force-fed will gain fat mass
        
        once allowed to regulate own diet, animal will eat less until fat levels return to normal
- - - - leptin is released by adipocytes (fat cells)
        
        Leptin: a hormone that communication with the brain about fat reserves
        
        ELEVATED leptin levels in blood activates hypothalamus
        
        decreases feeding behavior
        
        DECREASED leptin levels in blood activates hypothalamus
        
        increases feeding behavior
        
        ob/ob mice lack both copies of ob gene and are obese because WITHOUT LEPTIN brain THINKS fat reserves are low
        
        surgical fusion of normal moms and ob/ob mouse
        
        1 more item...
- - - - ANS
      - endocrine system
    - - activates homeostatic motivated behavior (feeding)
- - - - anorectic peptides (decrease feeding behavior)
        
        more aMSH and CART in arcuate nucleus (inhibits feeding behavior)
        
        increased metabolism
        
        increased energy expenditure
  - - - orexigenic peptides
        
        more NPY and AgRP in arcuate nucleus (stimulates feeding behavior)
        
        decreased metabolism
        
        decreased energy expenditure
- - - - arousal, sleep-wake, learning, memory
    - - regulates excitability of sensory thalamic nuclei
  - - - facilitates initiation of movement
    - - reinforces adaptive behaviors
      - determines the nature of stimuli as rewarding or aversive, and sends signals to the Nucleus accumbens
        
        Nucleus accumbens
        
        cocaine recptors
        
        cocaine prolongs action of DA
        
        enhances DA actions
        
        VTA
        
        opiate receptors and nAChRs