ANAT neuroanatomy of taste and olfaction

Question 1

5 sensations of taste
which release ATP
which release 5-HT

Answer 1

ATP:
    sweet
    umami
    bitter
5-HT:
    salty
    sour

Question 2

what type of receptors are olfactory receptors

ionotropic/metabotropic

Answer 2

metabotropic

GPCR

Question 3

what makes up CN 1 and pass through the cribriform plate

Answer 3

olfactory fila

Question 4

what is the route through which centrifugal fibers reach the olfactory bulb

Answer 4

AC (ant. commisure?)

Question 5

what does the olfactory tract contain

Answer 5

fibers of lateral olfactory tract
cells of anterior olfactory nucleus
fibers of anterior limb of anterior commisure

Question 6

olfactory bulb layered forebrain structure

what layers are here [6]

Answer 6

olfactory epithelium (SUPERFICIAL)
olfactory nerve (after cribriform plate)
glomerular layer
external plexiform layer
mitral cell layer
granule cell layer (DEEP)
lateral olfactory tract

Question 7

how does the glomerular layer receive input from other central nervous system areas

Answer 7

centrifugal afferents

Question 8

what is the principle interneuron of the olfactory bulb

Answer 8

granule cell

inhibitory

Question 9

f(x) of granule cells in the olfactory bulb

Answer 9

modulate olfactory bulb activity via feedback look

decrease activity of mitral and tufted cells

Question 10

what is a hallmark of the olfactory bulb
(for the most part)
what is the exception

Answer 10

projects directly to the cortex
does not relay via thalamus

piriform cortex

Question 11

what forms the lateral olfactory tract

where does it terminate

Answer 11

axons of mitral and tufted cells from caudal olfactory bulb

terminate on olfactory cortex (ventral areas of telencephalon)

Question 12

areas of the olfactory cortex

Answer 12

anterior olfactory nucleus
olfactory tubercle
piriform cortex
anterior cortical amygdaloid nuclues
periamygdaloid cortex
lateral entorhinal cortex

Question 13

where is olfactory information relayed to

???

Answer 13

insular and obitofrontal cortices
dorsomedial nucleus (thalamus)

Question 14

f(x) of orbitofrontal cortex

Answer 14

integrate olfactory, taste, and other food-related cues that produce experience of flavors

Question 15

after being relayed where is olfactory information directed to
???

Answer 15

lateral hypothalamus and hippocampus

Question 16

where does the lateral hypothalamus get its inputs from?

f(x)?

Answer 16

piriform cortex and anterior olfactory nucleus

important for feeding behavior

Question 17

where does the hippocampus get its inputs from?

f(x)?

Answer 17

entorhinal cortex

links olfactory input to learning and behavior

Question 18

anosmia

Answer 18

loss of smell

Question 19

hyposmia or olfactory hypesthesia

Answer 19

decreased sensitivity to odorants

can be associated w/ nasal polyps

Question 20

what does the chorda tympani of CN VII innervate in the peripheral taste pathway

Answer 20

fungiform papillae on anterior 2/3 of tongue

anterior foliate papillae

Question 21

what does the greater superficial petrosal nerve innervate in the peripheral taste pathway

Answer 21

taste buds on soft palate

Question 22

peripheral taste pathway

CN VII

Answer 22

enter brainstem @ pontomedullary jxn via intermediate nerve (CN VII) –> solitary tract (CN VII) –> target cells of solitary nucleus –> rostral portion of gustatory nucleus

GVA (caudal portion of gustatory nucleus)

Question 23

what does the lingual-tonsillar branch of CN IX innervate

Answer 23

taste buds in vallate papillae

posterior foliate papillae

Question 24

what does the superior laryngeal nerve of CN X innervate

Answer 24

taste buds of epiglottis and esophagus

Question 25

where are the cell bodies of the taste fibers of CN IX, X found

Answer 25

inferior ganglia (petrosal [IX] and nodose [X])

Question 26

peripheral taste pathway | CN IX

Answer 26

central processes enter medulla --> descend in solitary tract -->terminate on neurons in rostral portion of gustatory nucleus

Question 27

hallmark of the central taste pathway

Answer 27

exclusively ipsilateral

Question 28

central taste pathway

Answer 28

2nd order neurons travel via ipsilateral central tegmental tract --> parvicellular ventral posteromedial nucleus (VPMpc) 3rd order neurons travel via ipsilateral posterior limb of IC --> inner portion of frontal operculum and anterior insular cortex (rostral area of bradmann 3b on postcentral gyrus)

Question 29

what pathway is responsible for discriminative aspects of taste

Answer 29

central taste pathway | solitary nucleus --> VPMpc --> cortex

Question 30

lesion of root of CN VII or tumor in internal auditory meatus (vestibular schwannoma)

Answer 30

loss of taste from ipsilateral 2/3 of tongue paralysis of ipsilateral facial muscles hyperacusis (paralysis of stapedius m) impaired secretion of glands

Question 31

damage distal to geniculate ganglion

Answer 31

may or may not result in taste loss depending on origin of chorda tympani branches ipsilateral facial paralysis

Question 32

ageusia hypogeusia parageusia (dysgeusia)

Answer 32

- complete loss of taste - decreased taste sensitivity - distortions of taste perception