exam 3 Flashcards
outer ear
includes pinna & ear canal
pinna
external part of ear; helps funnel sound waves into ear canal
ear canal
tube leading into middle ear
hearing
transduction of vibrations
typanic membrane
eardrum; like the surface of a drum & it vibrates when contacted by sound waves; vibrates at the same frequency
ossicles
3 small bones that transmit sound from the eardrum to the oval window; they are the malleus (hammer), incus (anvil), & stapes (stirrup)
middle ear
includes typanic membrane & ossicles
cochlea
snail-shaped fluid-filled bony labyrinth that contains the oval & round windows
oval window
the area where stapes connects
inner ear
includes cochlea, oval & round windows, vestibular apparatus
vestibular apparatus
keeps you in the know of head/body orientation; has 3 semicircular canals
round window
helps release pressure & allow fluid to move in cochlea
hair cells
2 types: inner hair cells & outer hair cells
tonotopic organization
maintained throughout auditory system
how do you play with bats in summer
throw tennis balls
what did dr d do at boone lake
fishing; showed direction of sound
frequency
number of cycles per second; higher frequency = higher pitch; number of hertz
amplitude
size of the sound wave; physical intensity; measured in decibels
3 parallel canals
coiled in the cochlea; vestibular, middle, & tympanic canals
organ of corti
in cochlea; key structure for transduction of sound
tectorial & basilar membranes
2 flexible membranes in the middle canal; have hair cells in between that have fine stereocilia protruding on one side
inner hair cells
actual sensory receptors; 95% of auditory nerve; afferent signaling
outer hair cells
present in 3 rows; efferent signaling; act as tuner & protector; can affect TM
what happens when sound makes vibrations in the cochlea
fluid vibrates in the canals ⇛ the basilar membrane vibrates which bends stereocilia ⇛ tip links coordinate bending of cilia ⇛ potassium channels open ⇛ hair cells fire & send signal via auditory nerve
tip links
tie cilia together
what receives info from the brain to change stiffness of tectorial membrane
the outer hair cells; hyperpolarization = cells lengthen; depolarization = cells shorten
how does sound reach the cochlea
sound waves contact outer ear ⇛ pinna funnels waves into ear canal ⇛ tympanic membrane vibrates & moves ossicles ⇛ ossicles move oval window which vibrates to send waves to cochlea
A1 on heschl’s gyrus
where stimulation of different parts of cochlea is maintained up to
how does brain locate a sound
uses differences in latency & levels of sound stimuli between ears
interaural time difference
time lag between ears
interaural intensity difference
higher frequency sound intensity between ears
superior olivary complex
level in which interaural time & intensity differences happen; ITD = medial; IID = lateral
how do submarines navigate without vision
sonar = sound navigation & ranging; emitted sound bounces back to source, distance & features extrapolated by return signal
hearing loss
decreased sensitivity to sound (can be moderate to severe)
deafness
profound loss of hearing; cannot interpret spoken language even with hearing aid
conduction deafness
due to issues occurring in outer or middle ear; prevents conduction of vibrations to cochlea
sensorineural deafness
auditory fibers cannot fire & send signal to brain
central deafness
due to brain damage
word deafness
wernicke’s aphasia; comprehension of spoken words
cortical deafness
trouble with verbal & nonverbal auditory stimuli
cochlear implant
routine surgery that takes about an hour; over a million implanted worldwide; process involves many professionals
where does emotion cause perceivable changes
in the sympathetic & parasympathetic nervous systems; heart rate, sweating, etc.
hypothalamus is responsible for
feeding, fighting, fleeing, fornicating
function of orbitofrontal cortex
decision making, rewards, emotions; phineas gage damaged this
past studies for limbic systems include
the cat, the rat, & the amygdala (or lack of)
klüver-bucy syndrome
caused by bilateral lesions to the amygdala; over reaction to all objects, loss of fear, hypersexuality, hyperemotionality, etc.
damage to amygdala results in
lack of fear & fear learning
fear conditioning
pavlovian; a stimulus is paired with an averse shock; association is made & animal shows conditioned suppression
grand central station of sensory stimuli
thalamus
fear conditioning studies allow
in depth study of related brain structures
high road vs low road
high road is the longer route going to the visual cortex; low road is faster & it travels directly to amygdala
3 different planes of head movement
pitch (up & down), yaw (side to side), & roll (tilting left or right)
semicircular canals
connected at their ends to sac-like structures by the ampulla (enlarged area at the end of the canals) & connects to utricle & saccule
how does the vestibular system detect movement
with specialized receptors; just like cochlea there are hair cells; ampulla has cilia embedded in cupula (gelatinous matrix) which becomes displaced as fluid moves
how are utricle & saccule organized
they are considered otolith organs; 3 layers = membrane with hair cells, gelatinous layer with cilia embedded, & top layer of otolith crystals which provide weight
how do utricle & saccule function
help detect linear movement like stoplights
nystagmus
involuntary eye movement; pathological or physiological
vestibulo-ocular reflex
controls eye movements during head movement
caloric nystagmus
used to test the functioning of vestibular system; ear is irrigated & eye drift can be measured
C.O.W.S. test
cold opposite, warm same
video games
$135 billion industry
measuring movement
used as a method to study movement disorders
electromyography
used to assess the health of muscles & motor neurons that control them
skeletal muscles
basis for how we move; tendons connect muscles to bone
fast twitch muscles
great for generating short bursts of strength or speed; fatigue more quickly
slow twitch muscles
enable long endurance needs; fatigue more slowly
CNS/muscular interface
key to how we move our muscles
motoneurons
neurons that innervate muscles; transmit information from CNS to muscle to tell it to move
neuromuscular junctions
the synapse between the motoneuron & muscle; acetylcholine is used here
what happens after each motoneuron receives information from lots of other neurons
they leave the spine via ventral root & split their axons when they near the muscle to innervate several muscle fibers
innervation ratio
number of fibers a motoneuron innervates; low = fine motor, high = gross motor
proprioception
your sense of relative position of the body
pyramidal system (corticospinal system)
originates in frontal lobe in the primary motor cortex (m1) & is immediately in front of the central sulcus
how is the pyramidal system laid out
in similar fashion to the somatosensory cortex, but m1 cells are more sensitive to movement
what has occurred as a result of mapping m1
researchers have made brain-computer interface to move robotics
nonprimary motor cortex
can directly control movement via descending path or indirectly through m1
supplementary motor cortex
internally initiates movement
premotor cortex
guided by external stimuli
mirror neurons in premotor cortex
fire when initiating certain movements & when observing those same movements
brain structures that have major roles in initiating movements & determining amplitude/direction of movement
basal ganglia (forebrain), caudate nucleus, putamen, globus pallidus (interconnected with midbrain), & substantia nigra
cerebellum
part of hindbrain; deals with complexity of movement; timing & execution are also intricate in learning fine motor movements
flocculus
in cerebellum; controls posture & balance; talks to supplementary motor cortex & has topographical layout
muscular dystrophy
progressive weakness through loss of muscle mass; several classes; common underlying factor = mutations in dystrophin gene
what movement disorder is at the level of the muscles
muscular dystrophy
what movement disorder is at the level of the neuromuscular junctions
myasthenia gravis/autoimmune disease
myasthenia gravis
commonly affects eye, face, & esophageal muscles; classified as autoimmune disease; antibodies affect motoneuron/muscle communication
what movement disorder is at the level of the motoneuron
amyotrophic lateral sclerosis (ALS)
amyotrophic lateral sclerosis (ALS)
motoneurons begin to die & muscles atrophy; several causes being investigated such as gene mutations, too much glutamate, immune response, & protein mishandling
what movement disorders are at the level of the brain
huntington’s disease/huntington’s chorea & parkinson’s disease
huntington’s disease/huntington’s chorea
causes excessive movement; involuntary jerks/twitches that gets worse & eventual dementia; gradual damaging of cells in the basal ganglia due to mutation in huntingtin gene
tourette syndrome
similar to huntington’s disease but it is based on neurochemical imbalance & monoamines are likely involved
parkinson’s disease
profoundly affects motor movement; due to degeneration of dopamine cells in substantia nigra; treated with l dopa & deep brain stimulation
