ANAT neuroanatomy of taste and olfaction Flashcards
5 sensations of taste
which release ATP
which release 5-HT
ATP:
sweet
umami
bitter
5-HT:
salty
sourwhat type of receptors are olfactory receptors
ionotropic/metabotropic
metabotropic
GPCR
what makes up CN 1 and pass through the cribriform plate
olfactory fila
what is the route through which centrifugal fibers reach the olfactory bulb
AC (ant. commisure?)
what does the olfactory tract contain
fibers of lateral olfactory tract
cells of anterior olfactory nucleus
fibers of anterior limb of anterior commisure
olfactory bulb layered forebrain structure
what layers are here [6]
olfactory epithelium (SUPERFICIAL) olfactory nerve (after cribriform plate) glomerular layer external plexiform layer mitral cell layer granule cell layer (DEEP) lateral olfactory tract
how does the glomerular layer receive input from other central nervous system areas
centrifugal afferents
what is the principle interneuron of the olfactory bulb
granule cell
inhibitory
f(x) of granule cells in the olfactory bulb
modulate olfactory bulb activity via feedback look
decrease activity of mitral and tufted cells
what is a hallmark of the olfactory bulb
(for the most part)
what is the exception
projects directly to the cortex
does not relay via thalamus
piriform cortex
what forms the lateral olfactory tract
where does it terminate
axons of mitral and tufted cells from caudal olfactory bulb
terminate on olfactory cortex (ventral areas of telencephalon)
areas of the olfactory cortex
anterior olfactory nucleus olfactory tubercle piriform cortex anterior cortical amygdaloid nuclues periamygdaloid cortex lateral entorhinal cortex
where is olfactory information relayed to
???
insular and obitofrontal cortices dorsomedial nucleus (thalamus)
f(x) of orbitofrontal cortex
integrate olfactory, taste, and other food-related cues that produce experience of flavors
after being relayed where is olfactory information directed to
???
lateral hypothalamus and hippocampus
where does the lateral hypothalamus get its inputs from?
f(x)?
piriform cortex and anterior olfactory nucleus
important for feeding behavior
where does the hippocampus get its inputs from?
f(x)?
entorhinal cortex
links olfactory input to learning and behavior
anosmia
loss of smell
hyposmia or olfactory hypesthesia
decreased sensitivity to odorants
can be associated w/ nasal polyps
what does the chorda tympani of CN VII innervate in the peripheral taste pathway
fungiform papillae on anterior 2/3 of tongue
anterior foliate papillae
what does the greater superficial petrosal nerve innervate in the peripheral taste pathway
taste buds on soft palate
peripheral taste pathway
CN VII
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)
what does the lingual-tonsillar branch of CN IX innervate
taste buds in vallate papillae
posterior foliate papillae
what does the superior laryngeal nerve of CN X innervate
taste buds of epiglottis and esophagus
where are the cell bodies of the taste fibers of CN IX, X found
inferior ganglia (petrosal [IX] and nodose [X])
peripheral taste pathway
CN IX
central processes enter medulla –> descend in solitary tract –>terminate on neurons in rostral portion of gustatory nucleus
hallmark of the central taste pathway
exclusively ipsilateral
central taste pathway
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)
what pathway is responsible for discriminative aspects of taste
central taste pathway
solitary nucleus –> VPMpc –> cortex
lesion of root of CN VII or tumor in internal auditory meatus (vestibular schwannoma)
loss of taste from ipsilateral 2/3 of tongue
paralysis of ipsilateral facial muscles
hyperacusis (paralysis of stapedius m)
impaired secretion of glands
damage distal to geniculate ganglion
may or may not result in taste loss depending on origin of chorda tympani branches
ipsilateral facial paralysis
ageusia
hypogeusia
parageusia (dysgeusia)
- complete loss of taste
- decreased taste sensitivity
- distortions of taste perception
