Psyc417 Olfaction Taste

Questions while studying

Olfaction

What is the field of psychophysics? What are cranial nerves and what type of data do they transmit? What do G-protein coupled receptors have to do with olfaction? What are odorant receptors? What do they do? Where are they located?

<details> Olfactory receptors are receptors that bind to odorants (the volatile compounds that we smell). They are G-protien coupled receptors. Each Olfactory receptor (OR) can recognize multiple odorants, and one odorant can bind to multiple receptors. These cells regenerate over a period of weeks so permanent anosmia is rare. </details> Does odor smell the same to everyone? <details> No! </details> What is the brain cortex that registers smell <details> olfactory bulb</details> Why does olfactory bulbectomy not change total daily food intake in rats? Why are meal patterns altered by olfactory bulbectomy? When you kill the neurons in the olfactory epithelium, how do they grow back, why don't brain cells grow back? How can Alzheimer be diagnosed with a smell test? Describe the olfactory bulb: <details>  </details> How are smells masked? <details></details> How do herbivores and carnivores differ in their taste buds?

Taste

What are the three functions of taste?

<details> Identification (figure out what youre eating) Motivation (it makes you want to eat certain food) Preparation (Sweet taste releases insulin, and bitter taste decreases gastric motiity (how fast food travels)) </details> Why does bitter taste decrease gastric motility? How do animals react to sweet and bitter tastes? Why do some types of taste receptors regenerate at different rates? Which tastes are detected via ion-channels. Why are do homodimers of the T1R family not result in being able to taste. How does this whole system work? What are knockout mice? When something tastes super sweet, or super bitter, how does that work? What does the TRPM5 channel do? <details>When it is opened it evokes an action potential and can effect</details> What is a glomerulus? <details>Glomeruli are a bunch of synapses from one type of odorant receptor</details> How does lateral inhibition work? What is a supertaster and a non taster? What are salivary protiens and what do they have to do with bitterness and your perception of it? What are applications of salivary protiens? What can happen when an animal consumes a high tannin or quinine diet? What about sucrose octaacetate? Tell me about the cranial nerve that innervates taste buds. How can tonsillectomy damage your taste? <details>Sometimes tonsillectomies (or head and neck radiation) can damage the glossopharyngeal nerve which transmits data from the lingual branch</details> What is the function of the laryngeal epithelium taste buds? <details>protect the air ways</details> Name the 3 parts of the tounge <details>Fungiform (the front of the tounge) Foliate (posterial lateral margine fo tounge) Circumvallate (posterior dorsal (back) of tongue) </details> What nerve innervates the taste buds in the anterior tongue? What nerve innervates the lanryngeneal epithelium? What nerve innervates the taste budes in the palate? What nerve innervates the posterial tongue. What information does the trigeminal nerve carry? <details>pain, temperature, touch</details> What is TRPV1? What happens when trigeminal orosensory deafferentation happens?

Notes

Olfaction

Smell plays a role in eating high fat food When making mitral/tufted projection neurons in mice hyperactive, body weight decreases. People with disordered smell can cause both increased and decreased food & weight gain.

There is a genetic mutation that causes people to have higher or lower body-weight. People with the TT allele better smell food and have lower BMI. Human Kv1.3.

People that have a higher body weight have a decreased activation of their reward signals. Why?

If the sense of smell is lost early in life the body might regulate feed behaviors through other senses. There are some taste qualities that are not known since there is no known receptor for them:

• Calcium?
• Metallic?
• Water?

There are still a lot of stuff that is not known about taste and olfaction.

Taste

Animals have oral facial responses to primitive tastes.

Terminology:

Lingual taste buds are found in the papillae Fungiform papillae

Taste Buds

They are onion shaped structures There are 50-100 taste receptor cells per bud. The taste pore is a hole at the top of the bud that it uses to receive taste. Taste receptor cells are not neurons. Different taste receptors regenerate at different speeds.

There are taste buds that surround the tongue area.

Sour and salty tastes are detected via ion channels.

T1R family: (detects energy availability (sweet and umami))

• Homodimers do not lead to sweet or umami perception.
• T1R2 + T1R3 detects sweet.
• T1R1 + T1R3 detects umami.

GPCRs and Taste

Taste GPCR's contain alpha gustducin, and has beta and gamma subunits.

Genetic tools are frequently used to understand how biology works.

Sugar in mice and effects

Scientists found that when mice ate a lot of sucrose they become hyperactive and when they took a lot of sucrose early in life their memory was impaired.

T2R family: (gpcr) Contains 30-40 genes/types (it is more complicated than sweet and umami taste). Bitter taste means that something is bitter (in the wild) or that it is therapeutic. Bitter taste sensitivity differs among adult and kids (kids are more sensitive).

There are supertastes that are sensitive to other orosensory qualities (such as sweet or spicy)! This contributes to vegetables high in alkaline.

Salivary protiens protect against tannins in unripe fruits and make that taste more acceptable. If you expose animals to a high tannin or high quine diet it will upregulate the expression of salivary protiens.

Little is known about receptors for salt and sour taste.

Carnivors lose sweet taste while herbivores retain sweet taste even if they are not exposed to sweet taste. Some carnivores do not taste and they do not have taste buds. Penguines lost sweet, umami, and bitter taste.

Inner ear infections sometimes impact taste because it can damage the chorda tympani which innervates taste buds.

Taste nerve damage sometimes can cause burning mouth syndrome.

If you transect the cranial nerve that innervates a group of taste buds, the group of cells die.

Davis Rig Figures out the concentration dependent licking.

When an animal gets a nerve transectomy, it decreases the concentration dependent licking but not thaaaat much. The more nerve transection the more they lose their taste.

Eliminating taste will decrease body weight, this is different than smell.

When taste is removed, animals eat less frequently, which shows that animals are less motivated to consume food.

The palatability of food is also somewhat determined by the gut (if the food has nutriets then you want it).

Food tastes better when you've been losing weight, so if you are on a diet it makes it harder to control yourself when there is party.

TRPV1 and TRPM8 are the primary sensors of heat and cold temperatures respectfully. They are not limited to the oral cavity.

There are taste receptors everywhere in your body, same with the trigeminal sensors (i.e. if you put hot peper in your eye it burns.)

Trigmenial orosensory deafferation decreases body weight and it is causes the most drastic change in behavior.

Afferentation -> sensory stuff Efferentation -> motor stuff

Aphagia -> not eating Adipsia -> not drinking

Trigeminal transection removes the reflex for eating and drinking

Neurotracing

Neurotracing is to figure out he path of neurons and when they are stimulated.

Non-transynaptic tracer: only one synapse, e.g. Fluoro-gold Transsynaptic tracer: multiple synpases, e.g. pseudorabies virus.

Retrograde tracers shows where information is being received. Anterograde tracers is where information is going.

See Also

1. [[Main/zettelkasten/nutrition]] [[health]]
2. psyc417