Lecture 14 Flashcards
somatosensory topographic map
tells where everything is
highly consistent and predictable
huge representations of hands, lips, tongues
receptive field
the types of sensation that charge the response of a cortical neuron defines the receptive field the zone of excitation to the zone of inhibition center surround (on ff or off on) organization is common, creates contrast and specificity at the site of the stimulation
plasticity in brain, what happens if lose a limb
neurons in that zone become responsible to somatosensory information in adjacent regions
ex: if cut nerve in hand, cortical neurons no longer respond, after 5 months the neurons respond to touch on another part of the hand (shown with just using single fingers)
synesthesia
joined sensation’
color, taste, shape of someones voice
music sound perceived as shard of colored glass
numbers and letters having colors to them
most common in females, right handed
good memory, poor math skills
vibrating
compression and expansion of air molecules
amplitude
representation of pressure values, loudness
frequency
pitch, wavelength
the auditory system path
out ear (pinnae) to ear canal to ear drum (tympanic membrane) to ossicles (amplifies vibration) (incus, malleus, stapes) to oval window, cochlea and vagus nerve
cochlea
composed of three components (scala vestibuli, scala media, scala tympani)
scala media
basilar membrane and tectorial membrane
hair cells in basilar membrane project to tectorial
outer and inner hair cells
hair cells close are activated by high frequency
hair cells far are activated by low frequencies (apex)
basilar membrane
small and tight at beginning so only displaced by high frequency, wider and floppier at end so displaced by low frequency
movement stimulates hair cells
what happens when hair cells bend
potassium channels open, potassium flows in causing depolarization, which causes calcium channels to open so calcium flows in so then neurotransmitters are released, which stimulates axon attached and sends axon potential to brain
inner hair cells
hearing (stimulate auditory axons) and interpreting sounds and pass them on
use glutamate as transmitter, cause depolarization and action potential that goes into brain
outer hair cells
change length to control stiffness of basilar membrane (tighten basilar membrane to accommodate loud noise) uses acetylcholine as neurotransmitter causes action potential to brain
inner hair cell afferent and efferent
afferent- sending action potentials to the cochlear nucleus of brainstem
efferent- receive from lateral superior olivary nucleus
outter hair cells afferent and efferent
afferent- sending action potentials to the cochlear nucleus of brainstem
efferent- receive from medial superior olivary nucleus
how do we localize sounds
intensity differences (louder to one ear) latency differences timing differences (right v left ear)
binaural latency detection
detection in superior olfactory nucleus
if sound arrives at both ears at same time (C) right in front or right behind
if it arrives at either ear faster, (A or E)
tonotopic organization
maps in thalamus, auditory cortex, and inferior calculus, axons
axons activate different parts of inferior calculus based on different frequencies
place theory
you identify the pitch according to which inner ear hair cells are stimulated (ie which part of the basilar membrane is most vigorously vibrated)
volley theory
you can identify the pitch according to the firing rate of incoming APs
conduction deafness
eardrum and ossicles become damaged so no way for the sound to be conducted from outside world into cochlea
sensorineural deafness
damage in cochlea, connections between cochlea, and 8th nerve to cause deafness
central deafness
damage like stroke or some sort of injury in the auditory cortex itself which causes deafness
solutions to three types of deafness
conduction deafness- find some other way to stimulate cochlea (cochlear implant threaded electrode in cochlea, depolarization)
sensorineural deafness- putting in stimulatory electrodes on nerve itself or brain to help be aware of sounds
central deafness- in adulthood hard to fix
vestibular system
three fluid filled semicircular canals that join through their ampullae to the utricle and saccule
connected to cochlea
canals perpendicular to each other so swishes fluid in different directions
hair cells inside indicate what the movement is depending on the swishing
aware of body position
production of motion sickness
overproduction of vestibular system
