Palatability: Difference between revisions

'''Palatability''' (or '''palatableness''') is the [[hedonic]] [[reward system|reward]] (which is [[pleasure]] of [[taste]] in this case) provided by foods or fluidsdrinks that are agreeable to the "[[palate]]", which often varies relative to the [[homeostatic]] satisfaction of [[nutrition]]al, and/or [[Fluid balance|water]], or [[Food energy|energy]] needs.<ref>{{Cite journal |last1=Friedman |first1=M.Mark I. |last2=Stricker |first2=E.Edward M. |date=1976-11-01 |title=The physiological psychology of hunger: aA physiological perspective |journal=Psychological Review |language=en |volume=83 |issue=6 |pages=409–431 |doi=10.1037/0033-295X.83.6.409 |issn=00331939-295X1471 |pmid=1005583}}</ref> The palatability of a fooddish or fluidbeverage, unlike its [[Flavor (taste)|flavor]] or [[taste]], varies with the state of an individual: it is lower after [[eating|consumption]] and higher when [[hunger|deprived]]. It has increasingly been appreciated that this can create a hunger that is independent of homeostatic needs.<ref name="Lowe">{{Cite journal |last1=Lowe |first1=Michael R. |last2=Butryn |first2=Meghan L. |date=2007-07-24 |title=Hedonic hunger: aA new dimension of appetite? |journal=Physiology & Behavior |volume=91 |issue=4 |pages=432–439 |doi=10.1016/j.physbeh.2007.04.006 |issn=0031-9384 |pmid=17531274 |s2cid=10704679 }}</ref>

The palatability of a substance is determined by [[opioid receptor]]-related processes in the [[nucleus accumbens]] and [[ventral pallidum]].<ref name="Wassum">{{Cite journal |last1=Wassum |first1=K. M. |last2=Ostlund |first2=S. B. |last3=Maidment |first3=N. T. |last4=Balleine |first4=B. W. |date=2009-07-28 |title=Distinct opioid circuits determine the palatability and the desirability of rewarding events |journal=Proceedings of the National Academy of Sciences |language=en |volume=106 |issue=30 |pages=12512–12517 |doi=10.1073/pnas.0905874106 |issn=0027-8424 |pmc=2718390 |pmid=19597155 |bibcode=2009PNAS..10612512W |doi-access=free }}</ref> The opioid processes involve [[mu opioid receptor]]s and are present in the rostromedial shell part of the nucleus accumbens<ref>{{Cite journal |last1=Peciña |first1=Susana |last2=Berridge |first2=Kent C. |date=2005-12-14 |title=Hedonic Hot Spot in Nucleus Accumbens Shell: Where Do μ-Opioids Cause Increased Hedonic Impact of Sweetness? |journal=The Journal of Neuroscience |language=en |volume=25 |issue=50 |pages=11777–11786 |doi=10.1523/JNEUROSCI.2329-05.2005 |issn=0270-6474 |pmc=6726018 |pmid=16354936}}</ref> on its [[Medium spiny neuron|spiny neuron]]s.<ref>{{Cite journal |last1=Kelley |first1=A. E. |last2=Bakshi |first2=V. P. |last3=Haber |first3=S. N. |last4=Steininger |first4=T. L. |last5=Will |first5=M. J. |last6=Zhang |first6=M. |date=2002-07-01 |title=Opioid modulation of taste hedonics within the ventral striatum |journal=Physiology & Behavior |volume=76 |issue=3 |pages=365–377 |doi=10.1016/s0031-9384(02)00751-5 |issn=0031-9384 |pmid=12117573|s2cid=44258056 }}</ref> This area has been called the "opioid eating site".<ref>{{Cite journal |last1=Peciña |first1=S.Susana |last2=Berridge |first2=K.Kent C. |date=2000-04-28 |title=Opioid site in nucleus accumbens shell mediates eating and hedonic 'liking' for food: mapMap based on microinjection Fos plumes |journal=Brain Research |volume=863 |issue=1–2 |pages=71–86 |doi=10.1016/s0006-8993(00)02102-8 |issn=0006-8993 |pmid=10773195|s2cid=1805234 }}</ref>

It has also been suggested that "[[hedonic hunger"]] can be driven both in regard to "wanting" and "liking"<ref name="Lowe"/> and that a palatability subtype of neuron may also exist in the basolateral amygdala.<ref>{{Cite journal |last1=Fontanini |first1=Alfredo |last2=Grossman |first2=Stephen E. |last3=Figueroa |first3=Joshua A. |last4=Katz |first4=Donald B. |date=2009-02-25 |title=Distinct subtypes of basolateral amygdala taste neurons reflect palatability and reward |journal=The Journal of Neuroscience: The Official Journal of the Society for Neuroscience |volume=29 |issue=8 |pages=2486–2495 |doi=10.1523/JNEUROSCI.3898-08.2009 |issn=1529-2401 |pmc=2668607 |pmid=19244523}}</ref>

[[Appetite]] is controlled by a direct loop and an indirect one. In both the direct and indirect loops there are two feedback mechanisms. First a positive feedback involving its stimulation by palatability food cues, and second, a [[negative feedback]] due to satiation and satiety cues following ingestion.<ref>{{Cite journal |last=Smith |first=G.Gerard P. |date=2000-10-01 |title=The controls of eating: a shift from nutritional homeostasis to behavioral neuroscience |journal=Nutrition (Burbank, Los Angeles County, Calif.) |volume=16 |issue=10 |pages=814–820 |doi=10.1016/s0899-9007(00)00457-3 |issn=0899-9007 |pmid=11054585}}</ref> In the indirect loop these cues are learnt by association such as meal plate size and work by modulating the potency of the cues of the direct loop.<ref>{{Cite journal |last=Smith |first=G.Gerard P. |date=1996-01-01 |title=The direct and indirect controls of meal size |journal=Neuroscience and Biobehavioral Reviews |volume=20 |issue=1 |pages=41–46 |doi=10.1016/0149-7634(95)00038-g |issn=0149-7634 |pmid=8622828|s2cid=8313724 |doi-access=free }}</ref> The influence of these processes can exist without subjective awareness.<ref>{{Cite journal |last=Berridge |first=K.Kent C. |date=1996-01-01 |title=Food reward: brainBrain substrates of wanting and liking |journal=Neuroscience and Biobehavioral Reviews |volume=20 |issue=1 |pages=1–25 |doi=10.1016/0149-7634(95)00033-b |issn=0149-7634 |pmid=8622814 |s2cid=18707849 }}</ref>

The cessation of a desire to eat after a meal "satiation" is likely to be due to different processes and cues.<ref>{{Citation |last1=Dalton |first1=M. |title=Hedonics, satiation and satiety |date=2013-01-01 |work=Satiation, Satiety and the Control of Food Intake |pages=221–237 |editor-last=Blundell |editor-first=John E. |series=Woodhead Publishing Series in Food Science, Technology and Nutrition |publisher=Woodhead Publishing |doi=10.1533/9780857098719.4.221 |isbn=978-0-85709-543-5 |last2=Finlayson |first2=G. |editor2-last=Bellisle |editor2-first=France}}</ref> More palatable foods reduce the effects of such cues upon satiation causing a larger food intake, exploited in [[hyperpalatable food]].<ref>{{Cite journal |last1=Yeomans |first1=M. R. |last2=Lee |first2=M. D. |last3=Gray |first3=R. W. |last4=French |first4=S. J. |date=2001-08-01 |title=Effects of test-meal palatability on compensatory eating following disguised fat and carbohydrate preloads |journal=International Journal of Obesity and Related Metabolic Disorders: Journal of the International Association for the Study of Obesity |volume=25 |issue=8 |pages=1215–1224 |doi=10.1038/sj.ijo.0801653 |pmid=11477507|s2cid=37835293 }}</ref><ref>{{Cite journal |last1=Robinson |first1=Tristan M. |last2=Gray |first2=Richard W. |last3=Yeomans |first3=Martin R. |last4=French |first4=Stephen J. |date=2005-02-15 |title=Test-meal palatability alters the effects of intragastric fat but not carbohydrate preloads on intake and rated appetite in healthy volunteers |journal=Physiology & Behavior |volume=84 |issue=2 |pages=193–203 |doi=10.1016/j.physbeh.2004.11.004 |issn=0031-9384 |pmid=15708771|s2cid=33711162 }}</ref> In contrast, unpalatability of certain foods can serve as a deterrent from feeding on those foods in the future. For example, the [[Euphydryas chalcedona|variable checkerspot butterfly]] contains [[iridoid]] compounds that are unpalatable to avian predators, thus reducing the risk of [[predation]].<ref>{{Cite journal |last=Bowers |first=M. Deane |date=1981 |title=Unpalatability as a Defense Strategy of Western Checkerspot Butterflies (Euphydryas scudder, Nymphalidae) |jstor=2407845 |journal=Evolution |volume=35 |issue=2 |pages=367–375 |doi=10.2307/2407845 |pmid=28563381 |issn=0014-3820}}</ref>