Physiological Aspects of Sensory Pleasure In Foods

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Physiological Aspects of Sensory PleasureIn
Foods

• By
• Steven A. Witherly, PhD
• Bob Hyde, PhD

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Outline of Talk

• Sensory Pleasure (Hedonics) defined
• Hedonics Measurement
• Hedonic Effectors(s)
• Physiology of Sensory Hedonics
• Taste/Smell/Vision/Texture
• Hedonic Modulators

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Nutrition and Taste

• No food or beverage, no matter how healthful,
  will provide benefit...if it is unpalatable and
  thus unconsumed...Consumers have told us loudly
  and clearly that flavor is paramount in the
  enjoyment of food.

Dr. Beauchamp, March 9, 1999 Washington USDA
Conference
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Hedonic

• Derived from a Greek root (hedone) that means
• Sweet Taste (Honey, Figs)
• Pleasant
• Hedonics is the occurrence of pleasure, i.e.
  Sensory thrill (Booth)
• Innate learned mechanisms!!!

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Pain Pleasure

• Pain/Pleasure required for instinctual and
  acquired strategies
• Pain/Pleasure have innate rules (dispositions)
• Pleasure and pain reduction are separate but
  linked
• ? Body state Pain/Pleasure
• More pain than pleasure (survival)

Damasio INDescartes Error (1994)
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Pain/Pleasure

• Essential role in human life
• No treatise is available, little data
• Most primitive part of nervous system (Limbic)
• Distinct system ALWAYS linked to reinforcement

Bull. Acad. Natl. Med., 1831111 (99)
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Flavor Processing

• Flavor Processing involves cortical gustatory
  area plus amygdaloid and basal forebrain nuclei
• Flavor Taste Smell (Vision)

Small et al., Neuroreport 83913, (1997)
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Hedonics (?)
serotonin

• Liking pleasure/palatability
  opioid/GABA/ benzodiazepine
• Wanting appetite/incentive motivation MF
  Bundle
• Separate neural substrates
• Wanting/Liking can exist w/o awareness
• /- hedonics may be two separate systems.

Berridge Neurosci. Biobehav. Rev., 201 (96)
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Hedonics (?)

• Feelings Measurement
• Hedonics Liking (pleasure)
• Incentive Drive Wanting (Go for it)
• Orosensation Trigeminal Response
• Satiety Value Palatability (Gut)

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Sense of Taste

• Motivates and Directs Ingestion
• Differentiates toxins from nutrients
• Nutrition repletion causes hedonic appeal

Bitter Sweetness (Bad) toxins (Good)
Scott, Prog. Psychobiol. Physiol. Psy., 15231
(92)
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Dopamine and Hedonics

• Draws attention to Salient
• Events
• Enhances Sensory Awareness
• Short Term Pleasure
• Neurotransmitter

Gray et al., Science, 278, 1997
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Medial Forebrain Bundle
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Hedonic Modulators

• Capsaicin (Peppers)
• Beta-casomorphins (cheese)
• Benzodiazepine-Like Derivatives
• Taste Modifiers
• 5 Nucleotides L-Dopa
• MSG Aspartame
• Maltol Derivatives Garlic cmpds
• Di-Tri Peptides Lactones

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Fat Taste I

• Orosensory Perception Feel
• Fat, Fatty Acids activate taste cells in tongue,
  throat and upper third of the esophagussending
  pleasurable signals to brain.
• Fat Wide Range of textures (creamy)

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Fat Taste II

• INTRA duodenal infusion of lipid decreased PBN
  response to sucrose and NaCl - best neurons.
• Short latency effects (rats)
• Intestinal fat has specific suppressive effects
  on palatable food.

Hajnal et al., J. Neurosci., 197182 (99)
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Fat Taste IIIa

• Primate orbitofrontal cortex (OFC) site of
  convergence for taste, olfaction somatosensory
  areas.
• Neurons respond to the oral texture of fat (Real
  Silicone oil)

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Fat Taste IIIb

• Neurons response during feeding but not
  new foods (SSS)
• Therefore Reward value of the mouthfeel of fat
  isin the primate OFC.

Rolls et al, J. Neurosci., 191532 (99)
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Leptin Pleasure and Fat

• Leptin is a link between the brain
  pleasurable effects of eating
• Inc. Leptin self stimulation
• Dec. Leptin NPY galanin Eating
  Starvation
• Leptin also modifies opioid reward

Science, 287125 (2000)
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Odor Hedonics I

• About 1000 receptors/respond in distinct
  combinations (code)
• Primary Pathways are hedonic
• Hedonic Perception in Right Hemisphere
• Odor Memory in Left Hemisphere
• Odor Hedonically variable

Dr. Linda Buck, Cell, 961 (99)
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Odor Hedonics II

• Odors always linked to an emotional response.
• Greater variety of stock negative emotions than
  pleasant.
• Good aromas combine w/ taste pathways insula
  processing.
• Bad Odors Lights up the motor cortex.

J. Auton. Nerv. Syst. 751176 (1999)
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Odors/Emotions/ANS

• Odors Emotions CNS Response
• Possible to link ANS response to odor for Anger,
  Fear, Sadness, Surprise, Disgust, Happiness
• Objective measurement possible!!!

Vernet-Maury, J. Auton. Nerv. Syst., 15176 (99)
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Aroma Epigenetic Programs

• May be preprogrammed odor responses E Epigenetic
  Fruity means Vitamin C
• Odors E ANS Responses
• Objective Brain Measured Sensory Evaluation?

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Aromas Brain Stimulation

• Aromas Orbitofrontal Cortex (Right)
• Repeat Testing activity
• Trigeminal Aromas Widespread brain activation.
• Repeat Testing activity

? Aroma Trigeminal Aromas 6X Activation
Yousem, Radiology, 204 833 (97)
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TrigeminalAroma
Aroma Only
Methylsalicylate
Rosemary
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Sensory Specific Satiety

• Change in hedonics, not intensity, through
  exposure to sensory stimuli
• Repeated tastings reduce food pleasantness
• Sensory Specific (Taste, Aroma, Visual)

E.T. Barb Rolls
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Super Normal Stimulus (SS)

• 1. Increased attention to stimuli that are
  scarce and essential
• 2. When SS are present -- an exaggerated
  arousal and consummatory response
• 3. SS is innate and resistant to extinction

E.O. Wilson Consilience, 1998
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Typical Reaction to a
SuperNormal Stimulus
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Creation of a
SuperNormal Stimulus
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Oreo Hedonics

• Sensory Contrasts (Hyde I.C.E.)
• Taste/Texture/Aroma/Color
• Cocoa bitterness
• Additional arousal when Safe to Eatlearned

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Sensory Variability

• We live in our own sensory world - individual
  differences in sensory functioningeven with
  simple aromas and flavorswill not be similarly
  perceived as acceptable.

David Mela, Prepared Foods, July, 1996
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Supertasters and Pleasure I

• Individuals sensitive to PROP
• Groups non, medium, supertasters
• ST sweetness, bitterness, general
  orosensation
• Hedonic variability among groups
• Linked with Food aversions
• Bitter vegetable rejection

Bartoshuk, Neurosci Biobeh. Review 2079
(96) Drewnowski, Ann. NY.Acad. Aci., 855797 (98)
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Supertasters and Pleasure II

• Greater density of fungiform papillae
• Greater trigeminal innovation
• Greater FAT mouthfeel perception

Tepper, Ann. NY Acad. Sci., 855802 (98)
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Taste Hedonics...
Pregnancy...
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Hedonics Taste Pregnancy

• Hedonics change to support healthy pregnancy.
• Bitter perception. Changes in NaCl ( ),
  Sour ( ) and Bitter ( ) changes support a
  varied diet

Duffy Bartoshuk, Ann. NY Acad. Sci., 855805
(98)
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Marijuana Hedonics

• Taking marinol (tm) or Joints did not change
  intensity or hedonics ratings.
• Salivary rates reduced
• Recent studies show THC reduces self stimulation
  threshold. (MFB)

Mattes. Chemical Senses, 19125 (94)
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Hedonics and Satiety

• Hedonic ratings subject to sensory deprivation
• Food reward When hungry
• Alliesthesiagtgthis term

Cabanac, Physiol. Behav., 67, 409, 99
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Hedonics Emotion

• Hedonic eating was rated higher during joy than
  other emotions.

Macht, Appetite, 33129 (99)
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Hedonics Aging

• Oral disease
• Taste buds
• Sense of smell
• Neg. influence of drugs

Ship, Physiol. Behav., 66209 (99) See also
Schiffman reviews
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Hedonics Exercise

• Exercise Perceived pleasantness of foods.

Blundell, Eur. J. Clin. Nutr., 52300 (98)
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Hedonics Drugs

• Opioids / Benzodiazepines Hedonics
• Antidepressants often affects taste responses (
  )
• Antibiotics can cause dysgeusias

See Schiffman for Reviews
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Hedonics Opiate Peptides

• Naloxone (Opioids Antagonist) and opiate agonist
  butorphanol in 16 obese 25 normal weight
• Naloxone hedonic response in subject groups
• No effect on discrimination Intensity!

Drewnowski, AJCN 611206 (95) Arbisi, Appetite
32241 (99)
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SSRIs and Therapeutics

• Prozac Depression/Energizing/ SE
• Zoloft Depression/ SE
• Paxil Depression/Anxiety/ SE
• Serzone Depression/Anxiety/ SE
• Effexor Severe Depression/ SE
• SJW Depression/Anxiety/ NO SE

SE is Side Effects
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Salivation Hedonics

• As SSS salivation slows
• Salivation w/ new foods
• Salivation greater with trigeminal stimulants
• Salivation linked with pleasure

Wisienewski, Psychosom. Med. 59 427, 1997
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Real Hedonic Scale
Lo Pleasure Hi Lo Pain Hi Lo Wanting
Hi Lo Satiety Hi
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Conclusions

• Hedonic measurements are affected by many
  physiological
• parameters that may be difficult to control.
• Aroma perception highly idiosyncratic and
  unpredictable
• but very permanent once formed.
• Brain has separate neural systems for pain,
  pleasure,
• wanting and satiety. Which one does hedonics
  measure?
• We dont really know.
• Although a simple hedonic 9-point scale is the
  most widely
• used sensory test, it may be woefully biased
  and not reflect
• the true pleasure of the food at that moment of
  tasting.