4.3 the auditory system, sense of touch, the gustatory system and the olfactory system Flashcards
sound waves
provides basic input for our auditory experiences
sounds waves are simply the effect of air molecules on some physical disturbance
-frequency
-amplitude
frequency
we experience perceptually as the pitch of a sound based on the speed by which air molecules are displaced by the pressure of the original physical event which initiates the sound. the pressure from a sound pushes the molecules out as it emanates from the source, then the molecules return to their original position after the pressure travels beyond their location shorter wavelength (Hz) = higher frequency sounds (high pitched) longer wavelength (Hz) = lower frequency sounds (low pitched)
are there limits to what we are able to hear ?
yes ! humans can hear sounds from 15 Hz which is the absolute lowest, and about 20,000 Hz at the highest
amplitude
-height of the sound wave from the mid point
sound amplitude in decibels (dB)
-amount of displacement in the air molecules caused by sounds origin
-high amplitude sounds are louder than low amplitude sounds
Ear consists of _____ parts
3
- pinna
- auditory canal
- eardrum
pinna
outer ear
part of ear we see attached to our head
auditory canal
tube extending from the pinna to the eardrum
eardrum
sound strikes the eardrum and vibrate the eardrum and the same frequency and amplitude as the sound wave
ossicles
three little bones connected to the eardrum
1st is malleus (or hammer)
2nd is incus (or anvil)
3rd is stapes (or stirrup)
the vibrations of the eardrum causes these bones to also move as the same frequency and amplitude as the sound waves, and mainly function to provide a stronger signal from the eardrum before passing it down into the inner ear
cochlea
receives information about the sound waves from a connection with the stapes bone
filled with fluid and the interior of the cochlea contains a structure called the basilar membrane
basilar membrane
flexes in response to the tapping pattern provided by the stapes bone , which causes movement of the fluid inside the cochlea, this movement displaces hair cells along the basilar membrane, these hair cells are connected to the dendrite of neurons that send signals about sounds to the brain. these cells get bundled together into auditory nerves that project first to the brains thalamus then on to the primary auditory cortex in our temporal lobe
place theory of hearing
higher frequency sounds produce more displacement of hair cells nearest to the stapes
lower frequency sounds produce more displacement of hair cells further along the basilar membrane
-the idea is that the brain uses which hair cells are sending the strongest signals to determine whether a sound is higher or lower in pitch
frequency theory of hearing
the stapes taps against the cochlea at a frequency that matches the frequency of the sound wave striking the eardrum
the basilar membrane vibrates at this same frequency, causing hair cells along the basilar membrane to vibrate at that frequency too
*the theory is that hair cells send signals to the neurons connected to them according to the frequency that they are vibrating.
good explanation for lower frequency
*such signals would allow us to perceive the pitch of a sound in a way that relates directly to the frequency of a sound
volley principle
many neurons working as a team could alternate their firing to achieve a rate of firing well above 1,000 times per second
good explanation for lower frequency
sound localization
finding where a sound is coming from
sound typically arrives to each of our ears at slightly different times and we can use this to get an idea of where the sound is coming from, sound coming from the right will reach our right ear faster then our left
sounds will arrive at a higher intensity to whatever ear is oriented toward the origin of the sound, sound coming from the left will be received by your left ear at a higher amplitude than when it arrives at your right ear, your head will dampen the sound before it reaches the right ear, called sound shadow
sound shadow
head blocking/ dampening sound before sound reaches other ear
inferior colliculi
structure in brain responsible for processing info about the location of sound and guiding our orientation to new sounds that warrant our immediate attention
primary auditory cortex and secondary auditory cortex
once signals from the ears reach the primary auditory cortex in the temporal lobe, cells in that region are specialized to fire selectively in response to sounds corresponding to specific frequencies
structure of the region is very organized with neurons that respond to specific higher frequencies at one end and those that respond to lower frequencies at the other end the neurons in the primary auditory cortex project to the secondary auditory cortex for further processing, ultimately the brain does with this info results in all of our rich experiences of sound and our capacity to use sound perception to understand human speech
sense of touch
touch senses in our skin, muscles and joints give us info about the amount of pressure being applied to the surface of our bodies as well as info about the temperature of objects that come into contact with our skin
- haptics
- kinesthesis
somatosensory cortex
touch sensors send signals to the somatosensory cortex in the brains parietal lobes, sensitivity to pressure differs for different parts of the body.
we can easily perceive two points pressing close to one another against two different spots on our hand but two points of pressure at the same distance apart against other regions such as on our back is only experienced as one, these differences in sensitivity simply reflect the difference in the concentration of touch sensors across different regions of our bodies
haptics
active exploration of objects to learn their properties
-how the surface effects our touch sensors
kinesthesis
sensors in our muscles, joints, and tendons that gibe us a sense of the position of our body parts in space
-whether a pear is real or plastic
nocicpetion or pain perception
fast fibres
slow fibres
these get sent through the spinal cord
fast fibres
for sharp intense pain caused by injury
slow fibres
for the persistent, throbbing pain that persists after an injury occurs
gate control theory
the idea that some spinal cord cells send pain signals to the brain and others that inhibit transmission of pain signals to the brain
being in a state of arousal (or when distracted by other sensations) seems to activate the spinal cord fibres that suppress transmission of pain signals
-this explains why kicking a corner hurts more then tripping during a game
phantom limb pain
people who have lost a limb sometimes experience cramping shooting stabbing or burning pains coming from the limb that no longer exists.
the absence of activity in the part of the somatosensory cortex that register sensations from the missing limb, causes a hyper sensitivity in the neurons that are connected in that region and those neurons send pain signals in response to the absence of signals from the somatosensory cortex
mirror therapy
helps phantom limb pain
position mirror to make it look like there are both limbs
this gives them the feeling they can move their amputated limb again which settles down the pain signals that cause phantom limb pain
the gustatory system
basic components of taste are : salty, sour , bitter, sweet and umami
papillae
bumps on our tongue
capable of regenerating and they do every ten days
represent our sensory organs for taste
there are diff taste buds for diff primary tastes
connected to taste buds are the dendrites of neurons that send signals about the presence of dissolved molecules that come into contact with taste buds
signals from the tongue project first to the ______ then to the ___________, located in the ________
thalamus , primary gustatory cortex region, frontal lobes
-this leads us to identify familiar tastes
secondary gustatory cortex
also receives messages and provides the emotional experiences that accompany taste sensations
the determine whether you reaction to what you are tasting is emotionally positive or negative
olfactory system
sense of smell
substances in our environment release little bits of themselves into the air, these molecules float around in the air and find their way up into our noses, where they bind with receptors at the top of our nasal cavity
signals from our smell receptors project into our brain structure directly above called the olfactory bulb
olfactory epithelium
in the nasal cavity contains a layer of cells that host little hair cells called cilia
cilia contain sites that bind with particular molecules , we have a 1000 different types. the different smells we experience rely on the combined signals from more than one types of these receptor sites
olfactory bulb
connects with a number of diff areas of the brain which work together to provide us with the ability to identify smells and to experience positive and negative emotional reactions to them
auditory system
our ears collect sound waves, and our brains use that info to identify the source and interpret the content and location of noise. or just to enjoy the experience of listening
responsible for human communication throughout history
