This document discusses the senses of taste and smell (chemosenses). It notes that chemosenses provide survival value by allowing animals to detect chemicals in the air and dissolved in saliva. While some molecules can have similar structures but different smells, others can have different structures but be identified as the same smell. The human nose contains over 350 types of olfactory receptors that each detect particular odor groups. Taste is detected on the tongue by taste buds in specific areas. Both taste and smell involve complex neural processing and perception.
3. detect airborne
chemicals
detect chemicals
dissolved in saliva
Chemosenses provide survival value for animals
7. Some molecules
can have same
structures, but
different ¡°smells¡±
Others can have
different
structures and be
id¡¯d as same smell
8. 350 types of
olfactory receptors,
each sensitive to a
particular group of
odors.
Each olfactory
receptor neuron
contains only 1
type of olfactory
receptor.
11. The functional grpasocc. w/ a compound (COOH for acids;
OH for alcohols) determines the general area of the
olfactory bulb that is activated, and the compounds length
determines the position of the area.
16. Now add other odors, w/ their 100¡¯s of
molecules. We will not experience a
jumble¡here we¡¯ll smell coffee, bacon eggs!!!
17. Onion smell labeled pizza perceived
more positively than one labeled body
odor
18. Activity pattern in olfactory receptors the same. The label changed
perception & this was reflected in different activity of secondary ctx.
21. ¨C All over, no taste
buds
¨C Tip & sides
fungiform
¨C Folds along back &
sides
folaite
22. ? Site of transduction
? Each receptor cell
responds to a ltd # of
molecule types.
? Receptors synapse w/ 3
cranial nerves
¨C These also carry non-
taste info such as pain
&tmp
24. ? Rat studies indicate
some taste perception
is based on
distributed coding.
? Chemicals that
produced similar firing
patterns were
perceived as the same
(red & green lines)
26. ? Involves taste & olfaction
? Orbitofrontalctx combines
taste, olfaction, primary
somatosensory &what
pathway
? Has neurons that respond
to both taste & smell;
others taste & vision
? Often respond to similar
qualities (smell of sweet &
taste of sweet)
29. ? A.L. Fox (worked for
DuPont) prepped some
PTC., co-worker c/o
bitter taste from
dust¡.Fox tasted
nothing.
? A.F Blaheslee ( a
geneticist) dispensed
PTC to 2500 Ss at a
conference.
¨C 28%: ¡°tasteless¡±
¨C 66% ¡°bitter¡±
30. Why?
¨C Different # of receptors
¨C Some have specialized
neurons
Editor's Notes
Animals are able to detect chemical signals because they have Important evolutionary job ¨C keep genes in gene pool
Emotional reaction happen firstSmell has a direct link to the amgdyla
Dogs are better at smelling, It¡¯s because they have a lot more olfactory receptors, not because theirs are better
Olfactory neuron will only carry one olfactory kind of receptor
Olfactory receptor neurons are located in nose, send axons to glomerulus in olfactory bulb (right under the brain)Receptors distributed all over
Similar patterns of activity, then we perceive similar odorsDon¡¯t need to memorize the acids
Highly organized further organized by the size of the molecules
Red means lots of activityCool colors = less activityblack Arrows show that the activity is the sameWhite arrows show differences in activityRats can tell the different kind of carvone depending on the different activity of the neurons
Neuron enters the olfactory bulb, goes to the piriform cortex, then gets bounced to the orbitofrontal cortex, then straight to the prefrontal areaThe olfactory senses are the only ones that don¡¯t stop at the thalamus
This is why it takes a little longer for us to realize the emotional responseUsually, the olfactory was take the longer route
Expectation alters perception of how favorable the smell was
Subjects were told that it was either cheddar cheese or sweat, but it was actually both togetherChemical caused the exact same pattern of activity, the pattern of activity downstream was different depending on what they thought they were smelling
Umami, sour, bitter, salt, sugar
Know filiform, know that there are 4 forms of papillae
TASTE budshave receptors that bind together and at the tips, transduce
Area in the brain stem, first area information synapses
Olfaction and taste are linked downstream such that perception of taste is heavily dependent on olfactory Smell influences taste