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Brain and Behavior Exam 2 > Lec 24 Special Senses > Flashcards

Lec 24 Special Senses Flashcards

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1
Q

What is anosmia?

A

loss of smell

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2
Q

What is hyposmia?

A

decreased sensitivity to odorants

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3
Q

What is specific anosmia? possible cause?

A

inability to perceive odor of particular compound or class of compounds

  • usually genetic/congenital
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4
Q

what is hyperosmia/olfactory hyperesthesia? cause?

A

increased olfactory acuity

  • migraine, psychosis, substance abuse
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5
Q

What is olfactory agnosia? what does it suggest?

A
  • aware of smel lbut can’t recall name

suggests problem with higher cortical area

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6
Q

what is parosmia/dysosmia?

A

distorting in a small experience

can happen with seizures

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7
Q

what is phantosmia?

A
  • olfactory hallucination
  • perceptions of smeel when no odor present
  • happens in migraines/seizures
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8
Q

What is cacosmia? cause?

A

formation of disagreeable olfactory auras

  • epilepsy/psychiatric disorders
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9
Q

What causes olfactory hallucinations/cacosmia/parosmia?

A

epilepsy

psychiatric disorders

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10
Q

Which bone is cribiform plate a part of?

A

ethmoid bone

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11
Q

what are raccoon eyes? sign of what?

A

sign of basilar skull fracture – tears meninges –> blood goes into sinuses

have trouble with smell

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12
Q

How does infection/sinus disease affect sense of smell?

A
  • blocks access of odorants to olfactory epithelium
  • can cause edema of olfactory epithelium
  • treat with systemic anti-inflammatory drugs
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13
Q

how can viruses of URI effect smell?

A

can permanently damage olfactory epithelium

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14
Q

Where does seizures often originate from? why cause distorted smell?

A

originate from uncal region of temporal lobe

this is really close to olfactory bulb –> get cacosmia

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15
Q

How does olfaction change in aging?

A
  • normal decline with age
  • diminished peripheral sensitivity or altered central activity
  • can affect palatabiliyt of foods
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16
Q

What is association olfactory and neurodegenerative diseases?

A
  • involves central olfactory paths in alzheimers + parkinsons
  • appears early in course of disease
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17
Q

What 3 CNs are responsible for taste?

A

CN V: anterior 2/3
VN IX: posterior 1/3
VN X: epiglottis

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18
Q

Where do taste nerves project?

A

synpase in solitary nucleus –> to VPM of thalamus –> insula and frontal cortex

travels via internal capsule

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19
Q

Where is primary taste cortex?

A
  • frontal cortex

- insula

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20
Q

What is function of insula cortex vs frontal in taste response?

A

insula: specific interpretation of what you are eating
frontal: integration with other sensory stimuli

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21
Q

What is function of taste neurons that project to amygdala?

A

emotional response to what you are eating [yum vs yuck]

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22
Q

what are taste papillae?

A

consist of multiple taste buds [taste buds on lateral surface of papillae protuberances]

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23
Q

What are the functions of olfactory system?

A
  • detection/identification of odorants
  • intake regulation
  • detection of nonmicrobial hazards
  • role in human sexual behavior
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24
Q

What is unique about the olfactory tracts path to the cortex?

A

no stop over in thalamus [unlike the other senses] and goes straight to the olfactory cortex

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25
Q

What makes up the olfactory cortex?

A

piriform cortex = amygdala + incus + parahippocampal gyrus of temporal lobe

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26
Q

How does olfactory epithelium receive smell?

A
  • cilia on apical epithelium capture odorants
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27
Q

What parts of olfactory receptors neurons on basal olfactory epithelium? what about apical?

A

basal: small, unmyelinated axons
apical: dendritic process that expands into knob from which cilia with odorant receptors extend

28
Q

What are the basal cells of the olfactory epithelium?

A

stem cells that give rise to receptor cells

29
Q

What is function of bowmans glands in olfactory epithelium?

A

produce mucus

30
Q

What is contained in lamina propria?

A
  • bundles of olfactory axons, blood vessels, fibrous tissue, bowmans glands
31
Q

What is olfactory discrimination?

A
  • usually specificity of receptors for different odorants
32
Q

Ipsilateral or contralateral projections from olfactory bulb to olfactory neurons?

A

ipsilateral

33
Q

What are the glomeruli of the olfactory bulb?

A

synaptic target of primary olfactory axons

– site of synapse with apical dendrites of mitral cells

34
Q

what are mitral cells?

A

principal projection neurons of the olfactory bulb

35
Q

what are tufted and periglomerular cells?

A

local circuit neurons that send dendritic processes to glomeruli

  • can sharpen sensitivity of glomerular smell
36
Q

What are granule cells?

A

innermost layer of olfactory bulb

  • synapse on base dendrites of mitral cells
  • establish local lateral inhibitory circuits with mitral cells and participate in synaptic palsticity
37
Q

How do we localize smell?

A

process not totally clear, may be some sort of crossing over of fibers to inhibit contralateral side and help localize

38
Q

What are the 4 unique attributes of olfactory system?

A
  • somas of primary afferent neurons occcupy a surface epithelium
  • axons of primary afferents enter cerebral cortex directly [no thalamic relay]
  • primary afferent neurons undergo continuous turnover
  • path to cortical centers in frontal lobe entirely ipsilateral
39
Q

What are 3 main cell types in olfactory epithelium?

A
  • olfactory receptor neurons
  • supporting [sustentacular] cells
  • basal cells
40
Q

from what places does the olfactory bulb receive info?

A
  • from neurons in nose

- also top-down info from amygdala, neocortex, hippocampus, substantia nigra, locus coeruleus

41
Q

What is function of top down info that olfactory bulb receives?

A
  • discriminating among odors, enhanced sensitivity
42
Q

What does ability to detect odorous substance suggest about an olfactory lesion?

A

suggests the peripheral nerve and pathway are intact

43
Q

what does ability to identify what a specific odor is suggest about an olfactory lesion?

A

indicates that cortical function is intacts

44
Q

where is disorder likely to reside if pt is aware of smell but cannot recall name of scent?

A

likely in higher cortical levels of sensory system

45
Q

What types of lesions typically present with unilateral olfactory deficiency?

A

due to nasal cavity disease or following tumor-associated compression injury of one olfactory bulb/tract

46
Q

What types of lesions typically present with bilateral olfactory deficiency?

A
  • head injury or common cold

- also advanced cases of olfactory groove meningioma

47
Q

What types of neoplasms associated with olfactory dysfunction? unilateral or bilateral?

A
  • olfactory neuroblastomas or meningiomas

- unilateral if compression injury of 1 olfactory tract/bulb; bilateral in advanced cases

48
Q

what part of thalamus associated with taste?

A

VPM [ventral posterior medial]

49
Q

What is the function of reciprocal projections connecting the nucleus of solitary tract to hypothalamus and amygdala?

A
  • influence affective aspects of appetite [pleasure vs disgust] and satiety
50
Q

What is the function of the secondary neocortical taste area? where is it?

A
  • located in caudolateral orbitofrontal cortex
  • neurons there respond to combo of visual, somatic sensory, olfactory, gustatory stimuli
  • may be involved in conscious motivation to eat
51
Q

What is contained in a single taste bud?

A

40-60 taste receptor cells

52
Q

How long do taste cells last?

A

~ 2 wks, undergo continuous turnover

53
Q

What are the 5 different types of taste?

A
  • salt
  • sour
  • sweet
  • bitter
  • umami
54
Q

What are the 3 afferent nerves that innervate taste buds?

A
  • chorda tympani + greater petrosal of CN VII
  • lingual branch of CN IX
  • superior laryngeal branch of CN X
55
Q

Where is the nucleus of solitary tract located?

A

medulla

56
Q

What happens to 2nd order gustatory neurons from the solitary nucleus?

A

travel in central tegmental tract to VPM of thalamus

57
Q

What happens to gustatory neruons from VPM?

A

travel through ipsilateral posterior limb of internal capsule to inner portion of frontal operculum and anterior insular cortex

58
Q

Is the solitary nucleus –> VPM –> cortex path ipsilateral or contralateral?

A

exclusively ipsilateral

59
Q

Where does integration of multiple sensory stimuli with taste occur?

A

secondary taste area in orbitofrontal cortex

60
Q

What part of brain does affective associations with eating/food?

A

reciprocal projections from nucleus of solitary tract to hypothalamus and amygdala

61
Q

What is ageusia?

A

complete lost of taste

62
Q

what is hypogeusia?

A

decreased taste sensitivity

63
Q

what is gustatory hallucination?

A

perception of taste when none present

64
Q

What happens to taste in aging?

A

get progressive hypogeusia = decreased taste sensitivity

65
Q

what happens to taste if lesion of CN 7 root OR tumor in internal auditory meatus OR oropharyngeal tumor?

A

ipsilateral loss of taste perception from anterior 2/3 tongue

66
Q

What is effect of diabetes on taste?

A

progressive loss of taste sensation

Brain and Behavior Exam 2 (21 decks)

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