Brain and Behavior, Week 3 Flashcards
What’s the difference between the way nerves are myelinated in the periphery vs the central nervous system?
Periphery: Schwann cells (each one myelinates one segment of the nerve)
CNS: Oligodentrites myelinate multiple nerve fibers
Where are neuronal cell bodies for cranial nerves located? What’s the exception?
- Brain stem
- Olfactory nerve: goes directly to cortex
What anatomical feature of the skull is important for olfaction?
Cribiform plate
Why do people with Klinefelter syndrome tend to have anosmia?
GnRH releasing nerves are created in the nose during development and then migrate to the hypothalamus. The mutation(s) that causes KF syndrome is actually a defect in the olfactory system. GnRH neurons never make it to the hypothalamus.
How do unconscious saccadic movements work to maintain visual perception?
By constantly shifting focus, these movements ensure that the same image does not stay on the fovea for very long, thus preventing retinal desensitization.
Light causes _____ of the rods and cones and a _____ in their electrical potential:
- hyperpolarization
- decrease
What is the difference between rods/cones and bipolar cells on the one hand, and EPSP/IPSP cells on the other, in regard to action potentials.
- rods/cones/bipolar cells lack voltage gated sodium channels and therefore only have a graded response
- EPSP/IPSP cells have voltage gated sodium channels and therefore have action potentials
Compare and contrast rods vs cones:
Rods:
- Require only low levels of light
- Night vision
- Respond to one wavelength only
Cones:
- Require more light to activate
- Concentrated in the fovea
- Day vision
- 3 forms, which respond differently to different wavelengths
Which ligaments are important for maintaining the vibratory axis of the malleus, incus and stapes?
- malleal ligament
- incudal ligament
Outline the basic process by which hair cells trigger action potentials:
Hair cells in the organ of Corti are pressed up against the tectorial membrane during vibration, which stimulates action potentials in the vestibulocochlear nerve.
What neurotransmitter is released by gustatory afferent neurons?
Serotonin
Which cranial nerves convey information about taste?
- Facial (CN VII)
- Glossopharyngeal (CN IX)
- Vagus (CN X)
Which cranial nerves have a purely motor function?
- Accessory
- Hypoglossal
Which cranial nerves have a purely sensory function?
- Optic
- Olfactory
- Vestibulocochlear
Why are smell and emotion so closely linked?
A lot of the smell pathways are interlaced with limbic system pathways
What is the function of the pinhole device in an eye exam?
Helps screen for refractive errors
A patient presents with left superior quadrantopia. Where is the lesion?
Right temporal lobe
Tracts that carry information from the superior visual field pass through what part of the brain?
Temporal lobe
Tracts that carry information from the inferior visual field pass through what part of the brain?
Parietal lobe
In the swinging flashlight test, a paradoxical dilation indicates what?
Afferent pupillary defect
A patient reports seeing black dots that move in a swarm, as well as flashes of light resembling lightning. What’s the most likely diagnosis?
Retinal detachment
DDx:
- posterior vitreous detachment
- retinal tear
- aura of migraine
Risk factors for retinal detachment:
- Age (middle age, can be younger if myopic)
- Myopic
- Family Hx
- Trauma
- Intraocular surgery
Wet age-related macular degeneration (AMD):
- Blood vessel growth under macula, leading to scarring
- Driven by VEGF
- Treated with anti-VEGF therapy (monthly injections into eye: Avastin, Lucentis, or Eylea)
Advanced dry AMD:
- Caused by geographic atrophy
- Slowly progressive vision loss
- No way to prevent or treat
Most common cause of retinal detachment:
Posterior vitreous detachment
After cataracts and glaucoma, what is the most common cause of vision loss?
- Age related macular degeneration
- Diabetic retinopathy the most common cause among working-age people
What is the definition of “lazy eye” (amblyopia)?
- When one eye cannot be corrected to match the acuity of the other eye.
- Because the brain can’t focus eyes independently, it neglects the eye that requires more correction.
Most common etiology of viral conjunctivitis:
Adenovirus
Treatment for bacterial conjunctivitis:
Moxifloxacin (Vigamox) QID x 7d