GENETIC AND DEVELOPMENTAL FACTORS ON FEEDING

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GENETIC AND DEVELOPMENTALFACTORS ON FEEDING
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MAIN TOPICS

• GENETICS
• SOCIAL FACTORS
• ECOLOGICAL

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GENETICS

• PAPER I
• SPECIFICITY OF LEPTIN ACTION ON ELEVATED BLOOD
  GLUCOSE LEVELS HYPOTHALAMIC NEUROPEPTIDE Y GENE
  EXPRESSION

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SOCIAL FACTORS

• PAPER I
• SUSCEPTIBILITY OF ARTIFICIALLY REARED RAT PUPS
  TO SOCIAL INFLUENCES ON FOOD CHOICE
• PAPER II
• INTERACTION WITH DEMONSTRATORS RATS CHANGES OF
  OBSERVER RATS AFFECTIVE RESPONSE TO FLAVOURS

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• PAPER III
• A HISTORICAL PERSPECTIVE ON RECENT STUDIES OF
  SOCIAL LEARNING ABOUT FOODS BY NORWAY RATS

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ECOLOGICAL

• FOOD SELECTION PROBLEMS IN UNDERSTANDING HOW WE
  CHOOSE WE EAT

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GENETICS PAPER I

• INTRODUCTION
• LEPTIN CAUSES A DECREASE IN FOOD INTAKE NPY
  CAUSES AN INCREASE IN FOOD INTAKE.
• STUDIES HAVE RECENTLY SHOWN THAT SYSTEMATIC
  ADMINISTRATION OF LEPTIN RESULTED IN
  NORMALIZATION OF FOOD INTAKE IN BODY WEIGHT OF
  OB/OB MICE.
• STUDIES HAVE ALSO SHOWN THAT LEPTIN IN THE BRAIN
  NPY IN THE ARCULATE NUCLEUS ARE RESPONSIBLE FOR
  MEDIATING THESE EFFECTS.

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PROBLEMS

• RESULTS OF PREVIOUS STUDIES HAVE SHOWN THAT THE
  REVERSAL OF THE OBESE CONDITION OF THE OB/OB MICE
  RESULTS IN A DECREASE IN HYPOTHALAMIC NPY.
• GOAL OF THIS RESEARCH IS TO DETERMINE THE CAUSE
  FOR THE ABOVE STATED RESULTS.
• HYPOTHESIS
• 1. DUE TO THE SPECIFIC ACTION OF LEPTIN (DIRECT
  EFFECT)

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• LEPTIN ADMINISTRATION RESULTS IN NORMALIZATION OF
  OBESITY OVER EXPRESSION OF NPY IN THE ARCULATE
  NUCLEUS
• 2. DUE TO THE REVERSAL OF THE OBESE STATE IN
  ITSELF (IN DIRECT EFFECT)
• LEPTIN LOWERS FOOD INTAKE BODY WEIGHT THROUGH
  UNRELATED MECHANISMS.
• THIS RESULTS IN A REVERSAL OF OBESITY CONDITION
  (LOSS OF WEIGHT)
• AS A RESULT OF THIS REVERSAL, NPY LEVELS IN THE
  HYPOTHALAMUS ARE NORMALIZED.

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HOW WILL THIS QUESTION BE ANSWERED????THE
EXPERIMENTERS LOOKED AT - EFFECT OF LEPTIN
INJECTIONS ON HYPOTHALAMIC NPY LEVELS IN OB/OB
MICE BEFORE CHANGES IN BODY ADIPOSITY.- ASSESED
SPECIFICITY OF LEPTIN ACTION BY MEASURING NPY
LEVELS IN ARCULATE NUCLEUS IN TWO CONTROL SITES
(A) CEREBRAL CORTEX (B) HIPPOCAMPUS
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- EFFECT OF LEPTIN ON PVN LEVELS OF CRH (CONTROL
MEASURE FOR NP GENE EXPRESSION CRH INCREASES
INSULIN WHICH DECREASES FOOD INTAKE.
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METHODS

• SUBJECTS
• MALE OB/OB MICE N24
• MALE DB/DB MICE N12
• 12 HR DAY/NIGHT SCHEDULE
• INDIVIDUAL CAGES WITH CONTINUES ACCESS TO WATER.

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• PROCEDURE
• MICE TREATED FOR FIVE DAYS WITH INTRA PERITONEAL
  INJECTIONS OF EITHER SALINE (CONTROL) OR LEPTIN
  (TREATMENT)
• ALL INJECTIONS WERE A 150 ug.
• SALINE GROUP, OB GROUP, PAIR FED GROUP
• OB/OB GROUP
• EXPERIMENTAL GROUP OB - LEPTIN INJECTED, FREE
  FED.
• CONTROL GROUP SAL - SALINE INJECTED FREE FED
• CONTROL GROUP PAIR FED - SALINE INJECTED BUT
  PAIRED WITH MEMBERS OF THE OB GROUP WITH RESPECT
  TO THE AMOUNTS OF FOOD EATEN.

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• DB/DB GROUP
• EXPERIMENTAL GROUP OB - LEPTIN INJECTED FREE
  FED
• CONTROL GROUP SAL - SALINE INJECTED FREE FED
• DAILY MEASUREMENTS TAKEN OF EACH MOUSE
• (A) BODY WEIGHT
• (B) FOOD INTAKE
• AFTER 5 DAY TREATMENT, ANIMALS WERE SACRIFICED
• SLIDES WERE SELECTED FROM MID REGION OF THE
  ARCULATE NUCLEUS IN THE PVN

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RESULTS

• OB/OB GROUP
• OB TREATMENT GROUP
• DECREASE FOOD INTAKE BY 56
• DECREASE BODY WEIGHT BY 4.1
• DECREASE NPY LEVELS IN ARN BY 42.3
• THESE RESULTS FOR OB GROUP ARE STATED RELATIVE
  TO THE SAL CONTROL GROUP
• WHICH SHOWED NO SIGNIFICANT DECREASE IN FOOD
  INTAKE AND NPY LEVELS IN ARN. FURTHER MORE ,
  SAL GROUP EXPERIENCED AS INCREASE IN BODY
  WEIGHT OF 1.2.

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• PAIRED CONTROL GROUP
• DECREASE IN BODY WEIGHT (3.4)
• NO CHANGE IN NPY LEVELS IN ARN
• FOR ALL GROUPS LEPTIN INJECTIONS HAD NO AFFECT ON
  NPY LEVELS IN CEREBRAL CORTEX OR HIPPOCAMPUS OR
  LEVELS OF CRH IN THE PVN
• DB/DB GROUP
• LEPTIN ADMINISTRATION DID NOT AFFECT FOOD INTAKE,
  BODY WEIGHT OR NPY LEVELS EITHER IN THE ARN,
  CEREBRAL CORTEX OR HIPPOCAMPUS

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CONCLUSIONS

• REMEMBER THAT
• NPY INCREASES FOOD INTAKE
• LEPTIN DECREASES FOOD INTAKE
• THUS, INCREASED NPYDECREASED LEPTIN AND
  INCREASED LEPTINDECREASED NPY
• FINDING HIGH LEVELS OF NPY IN OB/OB MICE IS
  EXPECTED BECAUSE THEY DONT PRODUCE LEPTIN
• HOWEVER, SYSTEMATIC ADMINISTRATION OF LEPTIN
  DECREASES NPY LEVELS IN THE ARN OF OB/OB MICE

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• THIS IS DIRECT EVIDENCE THAT THE ARN-PVN NPY
  SYSTEM IS SUPPRESSED BY CIRCULATING LEPTIN

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EVIDENCE

• REDUCTION OF NPY IN ARN (43) AFTER 4.1 WEIGHT
  LOSS IN OB GROUP CAN CONCLUDE THAT THE EFFECT
  OF LEPTIN TO DECREASE NPY IN OB/OB MICE OCCURS
  BEFORE SIGNIFICANT CHANGES IN BODY ADIPOSITY.
• THE PAIRFED GROUP, WHICH LOST SIMILAR AMOUNT OF
  WEIGHT AS OB GROUP DID NOT EXPERIENCE DECREASE
  IN ARN NPY LEVELS.

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• CAN CONCLUDE THAT BODY WEIGHT DOES NOT DIRECTLY
  AFFECT LEVELS OF NPY, BUT IT MUST BE DUE TO
  SPECIFIC ACTION OF LEPTIN.
• IT APPEARS THAT A REVERSAL IN OBESE CONDITION OF
  OB/OB MICE RESULTS IN A DECREASE OF HYPOTHALAMIC
  NPY AS A DIRECT EFFECT O F LEPTIN AND NOT TO THE
  INDIRECT AFFECT OF WEIGHT LOSS.
• CONSEQUENTLY, REDUCED FOOD INTAKE AND BODY WEIGHT
  DO NOT MEDIATE EFFECT OF LEPTIN TO LOWER
  HYPOTHALAMIC NPY. RATHER LEPTIN ACTS DIRECTLY TO
  DECREASE NPY.

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3 ADDITIONAL OBSERVATIONS IN SUPPORT OF THIS
CONCLUSION.

• NPY DID NOT DECREASE IN CEREBRAL CORTEX OR
  HIPPOCAMPUS SUGGESTING THAT THE EFFECTS OF LEPTIN
  IS REGIONALLY SPECIFIC TO ARN NEURONS.
• LEPTIN DID NOT ALTER NPY LEVEKS IN THE ARN OF
  DB/DB MICE WHICH DID NOT RESPOND TO LEPTIN
• A. THIS SUGGESTS THAT INHERITED RESISTANCE TO
  LEPTIN RESULTS IN ARN NPY

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• NEURONS TO BE UNRESPONSIVE TO LEPTIN, THUS
  LEPTINS AFFECT N OB/OB MICE WAS NOT DUE TO A
  NONSPECIFIC OR TOXIC AFFECT.
• LEPTIN DID NOT INFLUENCE CRH LEVELS IN PVN OF
  EITHER OB/OB OR DB/DB MICE THUS INHIBITION OF NPY
  BY LEPTIN IS NOT CAUSED BY A GENERALIE
  HYPOTHALAMIC REACTION OF LEPTIN TO ALTER
  NEUROPEPTIDE GENE EXPRESSION.

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MODEL NEGATIVE FEEDBACK LOOP

• OB GENE EXPRESSION IN ADIPOSITYINCREASES WITH
  INCREASED LEVELS OF ADIPOSITY.
• NPY ACTS IN THE HYPOTHALAMAS TO PROMOTE WEIGHT
  GAIN IN FAT DEPOSITION BY INCREASING FOOD INTAKE.
• BUT, HICH LEVELS OF NPY WILL EVENTUALLY LEAD TO
  AN INCREASE IN LEPTIN WHEN ADIPOSITY LEVELS HAVE
  REACHED HIGH LEVELS

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LEPTIN INHIBITS NPY SYSTEM BY NEGATIVE FEEDBACK
LOOP AND CAUSES A DECREASE IN NPY AND FOOD INTAKE

• THUS, WHEN WEIGHT LOSS HAS OCCURRED LEPTIN LEVELS
  ALSO DECREASE
• WHEN LEPTIN DECREASES NPY INCREASES
• NPY THEN SIGNALS EATING TO RECOVER THE LOST
  WEIGHT .

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SOCIAL INFLUENCES PAPER I

• EXPERIMENT 1
• HYPOTHESIS NORMALLY REARED ANIMALS EXHIBIT A
  PROFOUND SOCIAL INFLUENCE OF THEIR DIET SELECTION
  THAN ANIMALS REARED IN SOCIAL ISOLATION.
• METHODS
• SUBJECTS
• A. OBSERVERS THIRTY 42-DAY-OLD RAT PUPS WHERE
  USED.

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• 15 IN EXPERIMENTAL GROUP AND 15 IN CONTROL
• DEMONSTRATORS THIRTY RAT PUPS 7-10 DAYS OLDER
  THAN OBSERVER PUPS
• APPARATUS
• FOOD PREFERENCES OF INDIVIDUAL OBSERVER RATS WERE
  TESTED IN LARGE , WIRE MESH HANGING CAGES THAT
  WERE DIVIDED INTO TWO EQUAL COMPARTMENTS BY A
  HARDWARE -CLOTH PARTITION.

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• PROCEDURE
• ISOLATION REARING
• REARED IN VISUAL AND TACTILE ISOLATION
• 15 OBSERVER RAT PUPS IN THE EXPERIMENTAL GRP.
• TAKEN AWAY FROM THEIR MOTHERS 2-3 DAYS AFTER
  THEIR BIRTH
• CANNULATION
• MAINTAINED ON A POLYSTYRENE CUP FLOATING IN A
  CONSTANT TEMP. BATH

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• UNTIL 18 DAYS OF AGE, FED ENRICHED MILK THROUGH
  CANNULA
• RAT PUPS PLACED ALONE IN SMALL, SHOE BOX CAGE
• WEANED FROM MILK TO PELLET OF PURINA CHOW
• NORMAL REARING
• 15 OBSERVER AT PUPS IN THE CONTROL GRP
• REARED BY THEIR MOTHER
• WEANED AT 21 DAYS OF AGE
• AD-LIB PELLETS OF PURINA CHOW
• GRPS OF 3 OR 4 IN SHOE BOX CAGES

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• AT 42 DAYS OF AGE, THE IDENTICAL PROCEDURE WAS
  EMPLOYED WITH ALL 30 OBSERVER PUPS
• 1. EACH OBSERVER PUP WAS INTRODUCED TO
• ONE COMPARTMENT OF A HANGING CAGE
• - ACCESS TO PELLETS OF PURINA CHOW
• - WATER
• -UNDISTURBED FOR 2 DAYS
• 2. DEMONSTRATED RAT PUPS WERE PLACED IN
  INDIVIDUAL CAGES IN A SEPARATED ROOM. ON EACH OF
  2 CONSECUTIVE DAYS
• - FOOD DEPRIVED FOR 23 DAYS
• -POWDERED PURINA CHOW FOR ONE HR.

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• 3. FOLLOWING THE THIRD, 23 HR PERIOD OF FOOD
  DEPRIVATION EACH DEMONSTRATOR WAS FED EITHER ONE
  GRAM OF DIET ANI OR 2.4 GRAMS OF DIET MAR TO
• 100GMS OF POWDERED PURINA CHOW FOR 1 HR.
• 4. IMMEDIATELY AFTER EATING EITHER DIETS EACH
  DEMONSTRATOR RAT WAS PLACED IN A HANGING CAGE ON
  THE OTHER SIDE OF THE HARDWARE-CLOTH BARRIER FROM
  ITS OBSERVER- INTERACTIVE FOR 30 MIN.
• 5. AFTER THE 30 MIN PERIOD OF INTERACTION
• - DEMONSTRATORS REMOVED FROM EXPERIMENT
• -FOR 22 HRS OBSERVER RATS WERE OFFERED A CHOICE
  OF DIET ANI OR DIET MAR.

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• 6. AT THE END OF THE 22HR PERIOD, EXPERIMENTERS
  MEASURING THE AMOUNT OF EACH OF THE TWO DIETS
  EATEN.

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RESULTS

• OBSERVERS ASSIGNED TO BOTH CONTROL ISOLATION
  REARED CONDITIONS
• 1. ATE A GREATER OF THE DIET THAN THEIR
  RESPECTIVE DEMONSTRATORS HAVE EATEN.
• 2. THERE WAS NOT A SIGNIFICANT DIFFERENCE
  BETWEEN THE MEAN EATEN OF THE OBSERVERS DIET IN
  COMPARISON TO WHAT THEIR DEMONSTRATORS HAD EATEN.

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• THEREFORE, RAT PUPS REARED IN SOCIAL ISOLATION
  ARE AS SENSITIVE TO SOCIAL INFLUENCES OF THEIR
  FOOD CHOICES AS ARE NORMALLY REARED RAT PUPS.

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EXPERIMENT 2

• HYPOTHESIS TO DETERMINE WHETHER SIMPLE EXPOSURE
  OF 42-DAY-OLD ISOLATION REARED RATS TO THE TASTE
  SMELL OF FOOD WOULD BE ENOUGH TO ENHANCE THEIR
  LATER FOOD PREFERENCES.
• METHODS
• SUBJECTS
• - 14 ISOLATION REARED RAT PUPS 14 NORMALLY
  REARED RAT PUPS.

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APPARATUS- LARGE WIRE-MESH HANGING CAGES
DIVIDED INTO 2 COMPARTMENTS BY HARDWARE-CLOTH
COMPARTMENT- ALSO USED IN EXP. 1

• PROCEDURE
• SAME AS EXP. 1 EXCEPT FOR
• NO DEMONSTRATORS WERE USED
• DURING STEP 4, RAT PUPS WERE EXPOSED FOR 30 MIN
  TO A SEMI-CIRCULAR, STAINLESS STEEL DISH
  CONTAINING EITHER DIET ANI OR DIET MAR.

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RESULTS

• ISOLATION REARED NORMALLY REARED RAT PUPS WERE
  SIMPLY EXPOSED TO A DIET
• 1. DID NOT EAT A GREATER OF THE DIET THEY WERE
  EXPOSED TO
• 2. DID NOT DIFFER FROM ONE ANOTHER IN THE MEAN
  EATEN OF THE DIET TO WHICH THEY WERE EXPOSED

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• THEREFORE, THE PREFERENCES BY RAT PUPS REARD IN
  ISOLATION FOR DIET EATEN BY THEIR DEMONSTRATORS
  IN EXP.1 , CANNOT BE EXPLAINED BY SIMPLE
  EXPOSURE TO DIET ANI OR DIET MAR DURING THE
  PERIOD OF INTERACTION BETWEEN DEMONSTRATORS
  OBSERVERS.

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SUMMARY

• THE SUSCEPTIBILITY TO SOCIAL INFLUENCE ON FOOD
  CHOICE IS VERY RESISTANT TO AN ABNORMAL EARLY
  LIFE.
• PREVIOUS SOCIAL EXPERIENCES DO NOT APPEAR TO PLAY
  A MAJOR ROLE IN THE DEVELOPMENT TO USE
  DEMONSTRATORS AS SOURCES OF INFORMATION ABOUT
  WHAT FOODS TO EAT.
• THIS TENDENCY SEEMS TO BE A SPECIES TYPICAL
  BEHAVIOUR

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SOCIAL INFLUENCES PAPER 2

• EXPERIMENT 1
• BACKGROUND INFORMATION
• THE GRILL NORGENS TASTE REACTIVITY TEST
  MEASURES BOTH POSITIVE NEGATIVE RESPONSES TO
  FLAVOUR.
• HOW IS IT ADMINISTERED???
• A FLAVOURED FLUID IS INTRODUCED INTO THE ORAL
  CAVITY OF A RAT (VIA CHRONIC CANNULA)

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• RATS OROFACIAL GENERAL MOTOR RESPONSES TO THE
  INFUSION ARE VIDEO TAPED FOR ANALYSIS
• POSITIVE RESPONSES
• 1. TONGUE PROTRUSIONS
• 2. LATERAL TONGUE PROTRUSIONS
• 3. PAW LICKING

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• NEGATIVE RESPONSES
• 1. GAPING
• 2. PASSIVE DRIPPING OF FLUID FROM MOUTH
• 3. PAW FLAILING
• 4. HEAD SHAKING
• 5. CHIN RUBBING

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PURPOSE

• TO EXAMINE WHETHER THE EFFECTS OF DEMONSTRATOR
  RATS ON THE FOOD CHOICES OF THEIR OBSERVERS,
  REFLECTED CHANGES IN THE OBSERVERS PERCEPTION OF
  THE PABILITY OF FOODS

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METHODS

• SUBJECTS
• 35 OBSERVERS THAT ARE EXPERIMENTALLY NAÏVE RATS (
  BORN IN CAPTIVITY )
• 35 DEMONSTRATOR RATS ( PREVIOUS SUBJECTS IN OTHER
  EXPERIMENTS)
• APPARATUS
• WIRE-MESH HANGING CAGES (HOUSED RATS INDIVIDUALLY
  )

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• CIRCULAR PLEXI GLASS TEST CHAMBER WHICH HOUSED
  RATS DURING TASTE REACTIVITY TEST
• PANASONIC COLOUR VIDEO CAMERA
• TEST FLUIDS
• 2 DISTINCT, EQUALLY PALLITABLE FLUID WERE USED IN
  THE EXPERIMENT
• FIRST FLUID CONSISTED OF 20 GMS OF UNSWEETENED
  COCOA 50 GMS OF SUGAR IN 1 LITRE OF WATER
  (FLUID COS)

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• SECOND FLUID CONSISTED OF 20 MIL LIT OF ALMONDS
  EXTRACTS 70 GMS OF SUGAR IN 1 LITRE OF WATER (
  FLUID ALS)

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PROCEDURE

• DAY 1 ALL OBSERVER RATS WERE IMPLANTED WITH A
  CHRONIC CANNULA
• DAY 2-3 RATS LEFT UNDISTURBED FOR 2 DAYS TO
  RECOVER FROM SURGERY
• DAY 4 HABITUATION DAY
• - RATS PLACED IN TEST APPARATUS FOR 10 DAYS
• -FOLLOWING 10 MIN. HABITUATION, RATS WERE PLACED
  ON WATER DEPRIVATION SCHEDULES

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• DEMONSTRATORS RATS DEPRIVED OF WATER FOR 23.5 HRS
  /DAY FOR 4 DAYS
• OBSERVER RATS DEPRIVED OF WATER FOR 23 HRS A DAY
  FOR NEXT 3 DAYS, SO THEY COULD BE TAUGHT A TASTE
  AVERSION TO FLUID COS FOR DAY 8
• DURING HALF HR. DRINKING PERIODS, WATER WAS GIVEN
  TO 19 DEMONSTRATOR RATS (CONTROL GRP.) FLUID
  COS WAS GIVEN TO THE REMAINING 16 DEMONSTRATOR
  RATS (EXPERIMENTAL GRP.)

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• DAY 5-7 TO HABITUATE RATS TO TEST PROCEDURES
• BEFORE EACH OBSERVER RATS 1 HR DRINKING PERIOD,
  IT WAS PLACED IN THE TEST CHAMBER FOR 4 MIN.
• WHILE IN CHAMBER RAT WAS INFUSED WITH WATER 1 MIL
  LIT/ MIN.
• DAY 8 TASTE AVERSION TOOK PLACE
• EACH OBSERVER RAT WAS GIVEN FLUID COS. INSTEAD OF
  WATER 1 HR., INJECTED WITH LITHIUM CHLORIDE
  SOLUTION

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• DAY 9 TESTING
• FOR 30 MIN, 19 DEMONSTRATORS (ASSIGNED TO
  INTERACT WITH CONTROL GROUP) WERE GIVEN WATER.
  REMAINING 16 DEMONSTRATORS RATS (ASSIGNED TO
  EXPERIMENTAL GROUP) WERE GIVEN FLUID COS
• UPON COMPLETION 30 MIN PERIOD, DEMONSTRATOR RATS
  WERE TRANSFERRED TO CAGES OF ASSIGNED OBSERVER
  RATS AND LEFT TO INTERACT FOR 30 MIN.
• AFTER INTERACTION, OBSERVER RATS A TASTE
  REACTIVITY TEST (RECOREDE D ON VIDEOTAPE)

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• SCORING OF VIDEOTAPES WAS CARRIED BY AN
  EXPERIMENTER WHO WAS UNAWARE OF OBSERVER RAT
  GROUP ASSIGNMENT
• UPON COMPLETION OF TEST RATS WERE RETURNED TO
  THEIR CAGES AND OFFERED A CHOICE FOR 22 HOURS
  BETWEEN 2 WEIGHED CUPS ONE CONTAINING COS AND
  THE OTHER ALS.
• AT THE END OF THE PREFERENCE TEST CUPS WERE
  WEIGHED AND OBSERVER RATS INTAKE WAS DETERMINED

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RESULTS

• PREFERENCE TEST
• OBSERVERS ASSIGNED TO EXPERIMENTAL GROUP SHOWED
  SIGNIFICANTLY WEAKER AVERSION TO FLUID COS OVER
  THE 22 HR. PERIOD THAN OBSERVER RATS IN THE
  CONTROL GROUP

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• TASTE REACTIVITY TEST
• OBSERVERS IN EXPERIMENTAL AND CONTROL GROUPS WERE
  EQUALLY LIKELY TO EXHIBIT POSITIVE RESPONSES
  (THAT IS WHEN THEY WERE GIVEN WATER)
• THOUGH OBSERVERS IN THE EXPERIMENTAL GROUP WERE
  SIGNIFICANTLY LESS LIKELY THAN THE OBSERVERS
  ASSIGN TO THE CONTROL TO EXHIBIT THE MOST COMMON
  NEGATIVE RESPONSES

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EXPERIMENT 2

• BACKGROUND INFORMATION
• IRWINS 2 POSSIBLE CAUSES OF DIFFERENTIAL
  RESPONSES EXHIBITED BY ANIMALS WHEN MAKING A
  CHOICE
• 1. A REFLEXIVE RESPONSE TO THE STIMULI PRESENT
  WHEN THE CHOICE IS MADE
• 2. A MOTIVATED RESPONSE THAT REFLECTS AN ANIMALS
  EXPECTANCIES REGARDING THE OUTCOMES OF THE
  BEHAVIOURS IT MIGHT EXHIBIT

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• IRWIN PROPOSED CHOICES MADE IN THE PRESENCE OF
  THE GOAL OBJECTS WERE BIASES (NUMBER 1 ABOVE),
  AND THAT DIFFERENCE RESPONSES MADE BY AN ANIMAL
  NOT DIRECTLY EXPOSED TO GAL OBJECTS WERE
  PREFERENCES (NUMBER 2 ABOVE).

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PURPOSE

• TO DETERMINE WHETHER SOCIAL INTERACTIONS CAUSE AN
  INCREASE IN OBSERVER MOTIVATION TO SEEK OUT FOODS
  THAT THEIR DEMONSTRATORS ATE.
• METHODS
• SUBJECTS- EIGHT 42 DAY-OLD OBSERVER RATS BORN IN
  CAPTIVITY AND EIGHT ADDITIONAL DEMONSTRATORS RATS
  (PREVIOUS SUBJECTS IN OTHER EXPERIMENTS).

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APPARATUS

• SHOE BOX CAGES (HOUSED RATS INDIVIDUALLY)
• A T-MAZE CONSTRUCTED OF PLEXIGLASS WITH STAINLESS
  STELL GRID FLOOR
• 2 FOOD CUPS, ONE AT EACH END OF THE ARM MAZE
• A LINE 5CM INSIDE THE ENTRANCE TO EACH ARM OF THE
  MAZE ( TO SERVE AS A BOUNDARY)

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PROCEDURE

• BOTH OBSERVER AND DEMONSTRATOR RATS WERE FED WELL
  BALANCED DIETS
• DURING FINAL 9WKS. OF EXPERIMENT, DEMONSTRATOR
  RATS WERE EITHER FED BANANA OR CHOW FLAVOURED
  PELLETS DURING THEIR ONE HOUR FEEDING PERIOD
  (OCCURRED TUESDAY AND FRIDAY OF FINAL 9 WKS.)

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• TRAINING OBSERVER RATS WERE TAUGHT TO RUN FROM
  THE START BOX OF THE MAZE TO BOTH GOAL BOXES
• EACH OBSERVER RAT RAN 10 TRIALS/DAY, UNTIL ALL
  WERE CONSISTANTLY ENTERING THE ARM OF THE MAZE
  CONTAINING THE BANANA FLAVOURED PELLETS MORE
  OFTEN THAN THE ARM CONTAINING THE CHOW FLAVOURED
  PELLETS
• TESTING OBSERVER RATS CONTINUED TO RUN MAZE 10
  TRIALS/DAY, 7 DAY/WKS
• TUESDAYS AND FRIDAYS OF EACH WEEK WAS ALLOWED TO
  INTERACT IN THEIR HOME CAGE WITH A DEMONSTRATOR
  FOR THIRTY MIN.

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• HALF OF THE DEMONSTRATOR RATS ATE BANANA
  FLAVOURED PELLETS OR CHOW FLAVOURED PELLETS THE
  HOUR PROIR TO INTERACTING
• EACH OBSERVER RAT WAS GIVEN 10 TRIALS/DAY IN THE
  T-MAZE WITH BANANA AND CHOW FLAVOURED PELLETS IN
  THEIR USUAL POSITIONS.

60
RESULTS

• EXPERIMENT REVEALED THAT 6 OF THE 8 OBSERVER RATS
  WERE SIGNIFICANTLY NORE LIKELY TO ENTER THE ARM
  OF THE MAZE CONTAINING BANANA FLAVOURED PELLETS
  ON DAYS THEIR DEMONSTRATORS HAD EATEN BANANA THAN
  ON DAYS WHEN DEMONSTRATORS HAD EATED CHOW
  FLAVOURED PELLETS

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• ACCORDING TO IRWINS DEFINITION OF PREFERENCE,
  CHOICES OF OBSERVERS INDUCED BY INTERACTION WITH
  DEMONSTRATORS WERE DUE TO CHANGES IN PREFERENCE
  AND NOT BIASES.

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SOCIAL INFLUENCES PAPERIII

• BACKGROUND
• STUDIES OF THE PAST 20 YEARS HAVE FOCUSED ON THE
  GOAL OF SOCIAL INTERACTION IN THE DEVELOPMENT OF
  ADAPTIVE PATTERNS OF FOODSELECTION BY NORWAY RATS

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• THEIR IMMEDIATE GOAL OF RESEARCH TO DETERMINE
  THE BEHAVIOURAL PROCESSES THAT CAUSE ONE RAT TO
  DIRECT ITS FEEDING BEHAVIOUR TOWARDS THE SAME
  FOODS THAT
• OTHERS OF ITS SOCIAL GROUP ARE EATING AND TO
  IGNORE POTENTIAL FOODS THAT OTHERS ARE NOT EATING

64
STUDIES

• GALEF AND CLARK (1971) STUDIED THE PHENOMENON
  DESCRIBED BY STEINIGER (1950) (POISON BAIT)
• CONDUCTED EXPERIMENTS WITH COLONIES OF WILD
  NORWAY RATS IN THE LAB.
• COLONIES LIVED IN SMALL (1 X 2 M) ENCLOSURES.

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• NON LETHAL, NAUSEAUTING CONCENTRATIONS OF MILD
  TOXINS INTRODUCED INTO DIET B (THE MORE
  PALLITABLE OF THE 2 DIETS, A B PRESENTED FOR 3
  HRS EACH DAY
• AVERSION TO DIET B DEVELOPED
• LITTERS OF RATS BORN TO THOSE WHO LEARNED
  AVERSION TO DIET B
• FOOD CHOICES OF WEANING RAT PUPS OBSERVED

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FINDINGS

• AS LONG AS YOUNG WERE LEFT IN CONTACT WITH ADULT
  MEMBERS OF THE COLONY, JUVENILES RAISED, ATE ONLY
  DIET A.
• ADULT WILD RATS COULD BIAS THEIR YOUNG TO EAT A
  RELATIVELY UNPALLITABLE SAFE FOOD (DIET A) AND TO
  IGNORE THE MORE PALLITABLE POTENTIALLY DANGEROUS
  FOOD (DIET B).
• AVOIDANCE OF DIET B IS NOT DUE TO THE SCENT
  MARKINGS BY ADULTS.

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RESULTS

• DURING INTERACTION WITH ADULTS, WILD RAT PUPS
  WERE LEARNING ONLY TO EAT THE FOODS THE ADULTS
  WERE EATING, NOT TO AVOID FOODS THAT ADULTS WERE
  AVOIDING

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MECHANISMS FOR SOCIAL LEARNING ABOUT FOODS IN
NORWAY RATS

• 1. PRESENCE OF ADULTS AT FEEEDING SITES e.g.
• - FOOD BOWL WITH ANAESTHESIZED FEMALE VS FOOD
  BOWL WITHOUT.
• - PUPS ATE 4X AS MUCH FOOD FROM BOWL WITH
  ANESTHESIZED FEMALE.
• -PUPS ATE FIRST MEALS OF SOLID FOOD IN PRESENCE
  OF ADULT
• 2. RESIDUAL OLFACTORY CUES e.g.
• - MARKING OF BOTH FOOD EATEN AREAS AROUND FOOD.
• -70-90 OF FOOD EATEN TAKEN FROM SOILED END OF
  CAGE

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• 3. FLAVOUR CUES MOTHERS MILK e.g.
• - CUES IN HER MILK REFLECTING FLAVOUR OF DIET.
• -AVERSION TO MILK FED FROM FEMALE EATING DIET
  OTHER THAN THEIR MOTHER
• -SIMILARITIES TO HUMANS IN DEVELOPING TASTES FOR
  CULTURALLY SPECIFIC FOODS ie. SPICY FOODS

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• 4. OLFACTORY CUES ON THE BREATH OF ADULT RATS
  e.g.
• - CUES FROM DIGESTIVE TRACT FOOD CLINGING
• TO FUR
• SIMPLE EXPOSURE OF OBSERVERS TO THE SMELL OR
  TASTE OF FOOD IS NOT SUFFICIENT TO ENHANCE
  OBSERVERS PREFERENCE FOR THAT FOOD.
• RAT PRODUCED ODOURS (SEMIOCHEMICALS ) SMELL OF
  FOOD PRESENTED TOGETHER INCREASES OBSERVERS
  PREFERENCES FOR THAT FOOD.

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IMPLICATIONS OF SOCIAL LEARNING FOR THE
DEVELOPMENT OF ADAPTIVE FORAGING BEHAVIOURS

• FEEDING BEHAVIOUR OF OTHER RATS INFLUENCES
  CHOICES OF FEEDING SITES FOODS
• THIS MAY HELP OUTSIDE THE LAB. IN LOCATING
  NUTRITIONALLY ADEQUATE FOODS, IDENTIFYING TOXINS,
  FORAGING MORE EFFICIENTLY.
• THEY CANNOT DO THIS WITHOUT SOCIAL CUES.

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• PUPS CANNOT LOCATE OR DEVELOP PREFERENCE FOR
  NUTRITIONALLY ADEQUATE FOOD ON THEIR OWN
• LEARNED FOR FOOD AVERSIONS DUE TO TOXICOSIS CAN
  BE ABANDONED AFTER EXPOSURE TO RATS THAT HAD
  EATEN THE AVERTED FOOD.

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ECOLOGICAL PAPER I

• FOOD SELECTION
• REQUIRES MORE THAN A NATURAL - SCIENCE BASED,
  REDUCTIONIST ANALYSIS LOOKING AT THE PHYSIOLOGY
  THE FEEDING BEHAVIOUR OF THE INDIVIDUAL
• INVOLVES ALSO THE INTERACTION BETWEEN THE
  INDIVIDUAL, ECOLOGICAL SOCIAL ENVIRONMENT.

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• ECOLOGY - WHICH FOODS THE ORGANISM EATS
• SOCIAL - FOODS AVAILABLE
• EVOLUTION SHAPES THE HEDONIC RESPONSES TO
  FLAVOURS THE TEXTURES
• PROBLEMS IN FEEDING BEHAVIOUR- INAPPROPRIATE
  AMOUNTS INAPPROPRIATE CHOICES OF FOOD

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FOOD CHOICE

• 2 CLASSES OF ANIMALS
• 1. DIETARY SPECIALISTS - SINGLE TYPE OF FOOD
• 2. DIETARY GENERALISTS- VARIETY OF DIFFERENT
  SUBSTANCES IN DIET
• ONCE ASSIGNED AS A SPECIALIST, WRONG TO ASSUME
  FOOD CHOICES MADE BY MEMBERS OF THAT SPECIES IS
  UNDERSTOOD

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FEEDING STRATEGIES EVOLVED IN ANIMALS

• 1. FOOD SELECTORS
• CHOOSE FOOD ITEMS WITH SIMILAR NUTRITIONALLY
  VALUE (SPECIALIST)
• PREDATORS SELECT PREY THAT WILL PROVIDE MORE
  ENERGY THAN WAS USED IN THEIR CAPTURE
  CONSUMPTION, THUS MAXIMIZING THE RATE OF NET
  ENERGY GAIN.

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• 2. DIET COMPOSERS
• SELECT FOOD OF VARYING NUTRITIONAL VALUE
  (GENERALIST )
• MORE COMPLEX PROCESS INVOLVED THAN FOOD SELECTORS
• OFTEN FAIL TO HAVE AN ADEQUATE DIET WITH ALL THE
  REQUIRED NUTRIENTS
• POSSESS BEHAVIOURAL MECHANISMS USED TO SELECT
  AVOID CERTAIN TYPES OF FOOD

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CONGENITAL HEDONIC RESPONSES

• OLFACTORY GUSTATORY SYSTEMS DISCRIMINATE
  RESPOND TO CHEMICAL STIMULI OF FOOD.
• ANIMALS IN NEW ENVIRONMENT - GUSTATORY SYSTEM
  PROVIDES NO PROTECTION AGAINST INGESTING TOXINS.
• FOOD PYRAMID - HEDONIC SCALE OF PALATABILITIES OF
  VARIOUS FOODS.

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• MOTIVATED TO EAT - BODY NOT DESIGNED TO COPE WITH
  THE HEDONICALLY DRIVEN SELECTION OF FOODS.
• RESULTS IN DISEASES- e.g.
• -TOOTH DECAY, OBESITY, CANCER OF GASTROINTESTINAL
  SYSTEM ASSOCIATE TO HIGH LEVELS OF FAT INTAKE.

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SUMMARY

• ALTHOUGH A CONGENITAL PATTERN OF HEDONIC
  RESPONSES EVOLVED TO GUIDE US IN FOOD SELECTION
  YOU CANNOT RELY ON WISDOM OF THE BODY FOR
  THESE CHOICES.
• EXPOSURE TO DIFFERENT FOODS INCREASED DIFFERING
  FROM THOSE EATEN BY OUR ANCESTORS

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• THEREFORE NOT VERY RELIABLE IN IDENTIFYING
  BETWEEN DESIRABLE OR TOXIC FOODS BASED ON THEIR
  SENSORY QUALITIES
• HARD TO SELECT HEALTHY FOOD DUE TO THE LARGE
  MARKET DEVOTED TO ADVERTISING JUNK FOOD.

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SELECTING FOODS

• PROLONG EXPOSURE TO AN UNPALATABLE FLAVOUR WILL
  PRODUCE AN EXCEPTANCE A PERVERSE PREFERENCE FOR
  THAT FLAVOUR.
• HOWEVER, FREQUENTLY EXPOSED TO A FOOD DURING A
  MEAL CAN LEAD TO A DECREASED LIKING TO THE FOOD.
• PREFERENCE FOR A FLAVOUR WILL BE ENHANCED WHEN
  PAIRED WITH A POSITIVE EVENT.

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• PREFERENCE FLAVOUR WILL CAUSE A TASTE AVERSION IF
  PAIRED WITH A NEGATIVE EVENT
• AN INDIVIDUAL IS MOST LIKELY TO INGEST CERTAIN
  FOODS IF AFFECTED BY THE INTERACTION WITH
  CONSPECIFICS EATING THAT FOOD.

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CONCLUSION

• ENVIRONMENTAL INFLUENCES AN INDIVIDUALS BIAS
  SELECTION OF FOOD - EXTERNAL CUES
• NEED TO EXAMINE FOOD SELECTION ACCORDING TO THE
  BIOLOGICAL SOCIAL ENVIRONMENT THE INDIVIDUAL IS
  EATING IN - NOT JUST THE PHYSIOLOGY OF FOOD
  INTAKE.

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SUMMARY

• GENETICS PAPER 1
• NPY INCREASES FOOD INTAKE AND LEPTIN DECREASES
  FOOD INTAKE
• HIGH LEVELS OF NPY IN OB/OB MICE IS EXPECTED
  BECAUSE THEY DO NOT PRODUCE LEPTIN
• HOWEVER, SYSTEMIC ADMINISTRATION OF LEPTIN
  DECREASES NPY LEVELS IN ARN OF OB/OB MICE

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• ARCULATE PVN-NPY SYSTEM IS SUPPRESSED BY
  CIRCULATING LEPTIN
• SOCIAL INFLUENCES PAPER 1
• SOCIAL INFLUENCE ON FOOD CHOICE IS RESISTANT TO
  AN ABNORNAL EARLY LIFE
• SOCIAL INFLUENCES ON FOOD INTAKE SEEMS TO BE A
  SPECIES TYPICAL BEHAVIOUR.

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• SOCIAL INFLUENCES PAPER 2
• OBSERVERS IN THE EXPERIMENTAL AND CONTROL GROUP
  ARE EQUALLY LIKELY TO EXHIBIT POSITIVE RESPONSE
  (TASTE REACTIVITY TEST)
• IRWINS DEFINITION OF PREFERENCE SHOWS THAT
  CHOICES OF OBSERVERS INDUCED BY INTERACTION WITH
  DEMONSTRATORS WERE DUE TO CHANGES IN PREFERENCE
  AND NOT BIAS

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• SOCIAL INFLUENCES PAPER 3
• 4 MECHANISMS FOR SOCIAL LEARNING ABOUT FOODS IN
  NORWAY RATS ARE
• 1. PRESENCE OF ADULTS AT FEEDING SITES
• 2. RESIDUAL OLFACTORY CUES
• 3. FLAVOUR CUES IN MOTHERS MILK
• 4. OLFACTORY CUES ON THE BREATH OF ADULT RATS

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• ECOLOGICAL PAPER 1
• FOOD INTAKE OR SELECTION OF FOOD INTAKE DEPENDS
  ON ENVIRONMENTAL INFLUENCES, BIOLOGICAL, AND
  SOCIAL ENVIRONMENT THE INDIVIDUAL IS EATING IN.