Neurogastronomy

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Neurogastronomy is the study of flavor perception and the ways it affects cognition and memory. This interdisciplinary field is influenced by the psychology and neuroscience of sensation, learning, satiety, and decision making. Areas of interest include how olfaction contributes to flavor, food addiction and obesity, taste preferences, and the linguistics of communicating and identifying flavor. The term neurogastronomy was coined by neuroscientist Gordon M. Shepherd. [1]

Contents

Olfaction and flavor

Human olfactory system. 1: Olfactory bulb 2: Mitral cells 3: Bone 4: Nasal epithelium 5: Glomerulus 6: Olfactory receptor neurons Olfactory system.svg
Human olfactory system. 1:  Olfactory bulb 2:  Mitral cells 3:  Bone 4: Nasal epithelium 5:  Glomerulus 6:  Olfactory receptor neurons

Out of all the sensory modalities, olfaction contributes most to the sensation and perception of flavor processing. Olfaction has two sensory modalities, orthonasal smell, the detection of odor molecules originating outside the body, and retronasal smell, the detection of odor molecules originating during mastication. [2] It is retronasal smell, whose sensation is felt in the mouth, that contributes to flavor perception. [1] Anthropologically, over human evolution, the shortening of the nasopharynx and other shifts in bone structure suggest a constant improvement of flavor perception capabilities. [1]

After mastication, odor molecules travel through the back of the mouth and up the nasopharynx. [2] The odorants are detected by myriad receptors on the olfactory epithelium. These receptors respond to a variety of dimensions of chemical properties. Odor receptors that respond to a dimension within a molecular receptive range are aggregated by glomeruli in the olfactory bulb. [3] Here, the multi-dimensional nature of odorant stimuli is reduced to two dimensions. This input undergoes edge enhancement, increasing its signal-to-noise ratio by way of lateral inhibition due to mitral cells stemming from the glomerular layer. [3] [1]

This input then reaches the olfactory cortex. Here, Hebbian learning networks allow for recall with partial or weak stimuli, indicating the first stage of conscious perception. [3] Here, connections with the hypothalamus and hippocampus indicate that olfaction stimuli affect emotion, decision making, and learning only after significant processing and rudimentary identification. [1]

Decision making

The hedonic value of food and its decision making relies on several concurrent neural processes. The attentional drive to seek and consume food is modulated by homeostatic signaling of hunger and satiety. Habit, social interactions, and nutritional needs affect this signaling. Analysis of non-human primates' orbitofrontal cortex suggests decision making is additionally modulated by food identification, independent of hunger. Activity in the medial orbitofrontal cortex and anterior singulate suggest that an affective value is assigned to every food identification. Hedonic pleasure increases when engaging with food consumption and peaks during satiety. Impairments in these systems greatly impact the ability to resist the urge to eat. [4] Imaging studies show that obese subjects with impairment in dopamine circuits that regulate hedonic value have issues with reward sensitivity and resist functional homeostatic signals that normally would prevent overeating. [5]

The consumption of comfort foods can facilitate feelings of relational connection and belonging, and the motivation behind pursuing certain foods can be modulated by social context and environment. [6]

Although the consumption of spicy food can cause pain, people in many cultures ascribe a high hedonic value to it. Psychologist Paul Rozin puts forth the idea of "benign masochism", a learned tendency that overrides the typically aversive stimuli because of the risk-taking or thrill-seeking associated with overcoming pain. [7]

Learned flavor preferences

Learned taste preferences develop as early as in utero, where the fetus is exposed to flavors through amniotic fluid. Early, innate, preferences exhibit tendencies towards calorie and protein dense foods. As children grow older, more factors such as peers, repeated exposures, environments and food availability will modulate taste preferences. [8]

Describing odors

While naming a flavor or food refines its representation strengthens its recall in memory, [9] the patterns and tendencies in word choice to describe flavor suggests limits to the our perception and communication. [10] In describing the flavor of wine, tasters tend to use words that function as a combination of visual and texture descriptors, and references to objects with similar odorant profiles. [10] Color perception heavily influences the word choice describing a flavor; the color of word's semantic reference is often congruent with the food's color when the taster can see the food. [11]

Clinical and other academic translations

With neurogastronomy's roots in neuroscience and psychology, clinical translation into research in obesity, diabetes, hypertension, eating disorders, chemoreceptive deficits in cancer treatments, etc. are explored in clinical neurogastronomy. [12] The term clinical neurogastronomy was coined by neuropsychologist Dan Han, to advocate for quality of life issues and positive clinical outcomes in patient populations. [13] In 2015, Gordon M. Shepherd, Dan Han, Frédéric Morin, Tim McClintock, Bob Perry, Charles Spence, Jehangir Mehta, Kelsey Rahenkamp, Siddharth Kapoor, Ouita Michel, and Bret Smith formed the International Society of Neurogastronomy (ISN). ISN is sponsored by the National Institutes of Health. [14] The inaugural meeting addressed multiple aspects of neurogastronomy concepts, and focused on its clinical translation including quality of life issues in cancer treatment and related smell and taste deficits, then followed by application into treatments for diabetes. Additional translational efforts included food technology, agriculture, climate change, and culinary arts. [15]

Related Research Articles

<span class="mw-page-title-main">Olfactory nerve</span> Cranial nerve I, for smelling

The olfactory nerve, also known as the first cranial nerve, cranial nerve I, or simply CN I, is a cranial nerve that contains sensory nerve fibers relating to the sense of smell.

<span class="mw-page-title-main">Olfactory bulb</span> Neural structure

The olfactory bulb is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell. It sends olfactory information to be further processed in the amygdala, the orbitofrontal cortex (OFC) and the hippocampus where it plays a role in emotion, memory and learning. The bulb is divided into two distinct structures: the main olfactory bulb and the accessory olfactory bulb. The main olfactory bulb connects to the amygdala via the piriform cortex of the primary olfactory cortex and directly projects from the main olfactory bulb to specific amygdala areas. The accessory olfactory bulb resides on the dorsal-posterior region of the main olfactory bulb and forms a parallel pathway. Destruction of the olfactory bulb results in ipsilateral anosmia, while irritative lesions of the uncus can result in olfactory and gustatory hallucinations.

Stimulus modality, also called sensory modality, is one aspect of a stimulus or what is perceived after a stimulus. For example, the temperature modality is registered after heat or cold stimulate a receptor. Some sensory modalities include: light, sound, temperature, taste, pressure, and smell. The type and location of the sensory receptor activated by the stimulus plays the primary role in coding the sensation. All sensory modalities work together to heighten stimuli sensation when necessary.

<span class="mw-page-title-main">Olfactory system</span> Sensory system used for smelling

The olfactory system or sense of smell is the sensory system used for smelling (olfaction). Olfaction is one of the special senses, that have directly associated specific organs. Most mammals and reptiles have a main olfactory system and an accessory olfactory system. The main olfactory system detects airborne substances, while the accessory system senses fluid-phase stimuli.

<span class="mw-page-title-main">Aroma compound</span> Chemical compound that has a smell or odor

An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently volatile for transmission via the air to the olfactory system in the upper part of the nose. As examples, various fragrant fruits have diverse aroma compounds, particularly strawberries which are commercially cultivated to have appealing aromas, and contain several hundred aroma compounds.

In medicine and anatomy, the special senses are the senses that have specialized organs devoted to them:

A topographic map is the ordered projection of a sensory surface, like the retina or the skin, or an effector system, like the musculature, to one or more structures of the central nervous system. Topographic maps can be found in all sensory systems and in many motor systems.

<span class="mw-page-title-main">Monell Chemical Senses Center</span>

The Monell Chemical Senses Center is a non-profit independent scientific institute located at the University City Science Center campus in Philadelphia, Pennsylvania. Monell conducts and publishes interdisciplinary basic research on taste, smell, and chemesthesis.

Olfactory fatigue, also known as odor fatigue, olfactory adaptation, and noseblindness, is the temporary, normal inability to distinguish a particular odor after a prolonged exposure to that airborne compound. For example, when entering a restaurant initially the odor of food is often perceived as being very strong, but after time the awareness of the odor normally fades to the point where the smell is not perceptible or is much weaker. After leaving the area of high odor, the sensitivity is restored with time. Anosmia is the permanent loss of the sense of smell, and is different from olfactory fatigue.

<span class="mw-page-title-main">Rachel Sarah Herz</span> American-Canadian psychologist

Rachel Sarah Herz is a Canadian and American psychologist and cognitive neuroscientist, recognized for her research on the psychology of smell.

Dysosmia is a disorder described as any qualitative alteration or distortion of the perception of smell. Qualitative alterations differ from quantitative alterations, which include anosmia and hyposmia. Dysosmia can be classified as either parosmia or phantosmia. Parosmia is a distortion in the perception of an odorant. Odorants smell different from what one remembers. Phantosmia is the perception of an odor when no odorant is present. The cause of dysosmia still remains a theory. It is typically considered a neurological disorder and clinical associations with the disorder have been made. Most cases are described as idiopathic and the main antecedents related to parosmia are URTIs, head trauma, and nasal and paranasal sinus disease. Dysosmia tends to go away on its own but there are options for treatment for patients that want immediate relief.

<span class="mw-page-title-main">Odor</span> Volatile chemical compounds perceived by the sense of smell

An odor or odour is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and many animals can perceive via their sense of smell. An odor is also called a "smell" or a "scent", which can refer to either an unpleasant or a pleasant odor.

<span class="mw-page-title-main">Sense of smell</span> Sense that detects smells

The sense of smell, or olfaction, is the special sense through which smells are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste.

Olfactory memory refers to the recollection of odors. Studies have found various characteristics of common memories of odor memory including persistence and high resistance to interference. Explicit memory is typically the form focused on in the studies of olfactory memory, though implicit forms of memory certainly supply distinct contributions to the understanding of odors and memories of them. Research has demonstrated that the changes to the olfactory bulb and main olfactory system following birth are extremely important and influential for maternal behavior. Mammalian olfactory cues play an important role in the coordination of the mother infant bond, and the following normal development of the offspring. Maternal breast odors are individually distinctive, and provide a basis for recognition of the mother by her offspring.

Extinction is a neurological disorder that impairs the ability to perceive multiple stimuli of the same type simultaneously. Extinction is usually caused by damage resulting in lesions on one side of the brain. Those who are affected by extinction have a lack of awareness in the contralesional side of space and a loss of exploratory search and other actions normally directed toward that side.

A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of stimuli. Although, in some cultures, five human senses were traditionally identified as such, many more are now recognized. Senses used by non-human organisms are even greater in variety and number. During sensation, sense organs collect various stimuli for transduction, meaning transformation into a form that can be understood by the brain. Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior and thought.

Gordon Murray Shepherd was an American neuroscientist who carried out basic experimental and computational research on how neurons are organized into microcircuits to carry out the functional operations of the nervous system. Using the olfactory system as a model that spans multiple levels of space, time and disciplines, his studies ranged from molecular to behavioral, recognized by an annual lecture at Yale University on "integrative neuroscience". At the time of his death, he was professor of neuroscience emeritus at the Yale School of Medicine. He graduated from Iowa State University with a BA, Harvard Medical School with an MD, and the University of Oxford with a DPhill.

<span class="mw-page-title-main">Sniffing (behavior)</span> Nasal inhalation to sample odors

Sniffing is a perceptually-relevant behavior, defined as the active sampling of odors through the nasal cavity for the purpose of information acquisition. This behavior, displayed by all terrestrial vertebrates, is typically identified based upon changes in respiratory frequency and/or amplitude, and is often studied in the context of odor guided behaviors and olfactory perceptual tasks. Sniffing is quantified by measuring intra-nasal pressure or flow or air or, while less accurate, through a strain gauge on the chest to measure total respiratory volume. Strategies for sniffing behavior vary depending upon the animal, with small animals displaying sniffing frequencies ranging from 4 to 12 Hz but larger animals (humans) sniffing at much lower frequencies, usually less than 2 Hz. Subserving sniffing behaviors, evidence for an "olfactomotor" circuit in the brain exists, wherein perception or expectation of an odor can trigger brain respiratory center to allow for the modulation of sniffing frequency and amplitude and thus acquisition of odor information. Sniffing is analogous to other stimulus sampling behaviors, including visual saccades, active touch, and whisker movements in small animals. Atypical sniffing has been reported in cases of neurological disorders, especially those disorders characterized by impaired motor function and olfactory perception.

Retronasal smell, retronasal olfaction, is the ability to perceive flavor dimensions of foods and drinks. Retronasal smell is a sensory modality that produces flavor. It is best described as a combination of traditional smell and taste modalities. Retronasal smell creates flavor from smell molecules in foods or drinks shunting up through the nasal passages as one is chewing. When people use the term "smell", they are usually referring to "orthonasal smell", or the perception of smell molecules that enter directly through the nose and up the nasal passages. Retronasal smell is critical for experiencing the flavor of foods and drinks. Flavor should be contrasted with taste, which refers to five specific dimensions: (1) sweet, (2) salty, (3) bitter, (4) sour, and (5) umami. Perceiving anything beyond these five dimensions, such as distinguishing the flavor of an apple from a pear for example, requires the sense of retronasal smell.

<span class="mw-page-title-main">Olfactic communication</span> Social interaction through smell

Olfactic communication is a channel of nonverbal communication referring to the various ways people and animals communicate and engage in social interaction through their sense of smell. Our human olfactory sense is one of the most phylogenetically primitive and emotionally intimate of the five senses; the sensation of smell is thought to be the most matured and developed human sense.

References

  1. 1 2 3 4 5 Shepherd, Gordon M. (2013-07-16). Neurogastronomy : how the brain creates flavor and why it matters. ISBN   9780231159111. OCLC   882238865.
  2. 1 2 Rozin, Paul (1982). ""Taste-smell confusions" and the duality of the olfactory sense". Perception and Psychophysics. 31 (4): 397–401. doi: 10.3758/BF03202667 . PMID   7110896.
  3. 1 2 3 I., Basbaum, Allan (2008-01-01). The senses a comprehensive reference. Elsevier. ISBN   9780126394825. OCLC   844328507.{{cite book}}: CS1 maint: multiple names: authors list (link)
  4. ↑ Kringelbach, Morten L. (2015-03-02). "The pleasure of food: underlying brain mechanisms of eating and other pleasures". Flavour. 4 (1): 20. doi: 10.1186/s13411-014-0029-2 . ISSN   2044-7248.
  5. ↑ Volkow, Nora D.; Wang, Gene-Jack; Baler, Ruben D. (2011-01-01). "Reward, dopamine and the control of food intake: implications for obesity". Trends in Cognitive Sciences. 15 (1): 37–46. doi:10.1016/j.tics.2010.11.001. ISSN   1364-6613. PMC   3124340 . PMID   21109477.
  6. ↑ Troisi, Jordan D.; Gabriel, Shira; Derrick, Jaye L.; Geisler, Alyssa (2015-07-01). "Threatened belonging and preference for comfort food among the securely attached". Appetite. 90: 58–64. doi:10.1016/j.appet.2015.02.029. PMID   25728881. S2CID   43102417.
  7. ↑ "22nd APS Annual Convention (2010) - Presidential Symposium - Paul Rozin". Vimeo. Retrieved 2017-05-09.
  8. ↑ Ventura, Alison K.; Worobey, John (2013-05-06). "Early Influences on the Development of Food Preferences". Current Biology. 23 (9): R401–R408. doi: 10.1016/j.cub.2013.02.037 . ISSN   0960-9822. PMID   23660363.
  9. ↑ J., Stevenson, Richard (2010-01-01). Learning to Smell Olfactory Perception from Neurobiology to Behavior. Johns Hopkins University Press. ISBN   9780801888946. OCLC   956771635.{{cite book}}: CS1 maint: multiple names: authors list (link)
  10. 1 2 Brochet, Frédéric; Dubourdieu, Denis (2001-05-01). "Wine Descriptive Language Supports Cognitive Specificity of Chemical Senses". Brain and Language. 77 (2): 187–196. doi:10.1006/brln.2000.2428. PMID   11300703. S2CID   34627633.
  11. ↑ Morrot, Gil; Brochet, Frédéric; Dubourdieu, Denis (2001-11-01). "The Color of Odors". Brain and Language. 79 (2): 309–320. doi:10.1006/brln.2001.2493. PMID   11712849. S2CID   10002492.
  12. ↑ "A Matter of Taste".
  13. ↑ "Clinical neurogastronomy for quality of life outcomes". 18 November 2015.
  14. ↑ "International Society of Neurogastronomy".
  15. ↑ "Birth of a Neurogastronomy Nation: The Inaugural Symposium of the International Society of Neurogastronomy".
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