Transcript Slide 1

Audition: The sense or act of hearing.
Two bundles of aging outer hair cells
showing severe degeneration. The
outer hair cells are responsible for
fine tuning and amplifying the
sounds that are detected by the
inner hair cells. This age-related
degeneration of hair cells is
responsible for the hearing loss often
associated with aging.
The Ear
Outer Ear: Pinna. Collects sounds.
Middle Ear: Chamber between eardrum and
cochlea containing three tiny bones (hammer,
anvil, stirrup) that concentrate the vibrations
of the eardrum on the cochlea’s oval window.
Inner Ear: Innermost part of the ear, containing
the cochlea, semicircular canals, and vestibular
sacs.
There are two theories……..
Theories of Audition
Helmholtz Place Theory suggests that sound
frequencies stimulate the basilar membrane at
specific places resulting in perceived pitch.
http://www.pc.rhul.ac.uk
Frequency Theory states that the rate of nerve
impulses traveling up the auditory nerve matches
the frequency of a tone, thus enabling us to sense its
pitch.
Sound
Frequency
100 Hz
200
Auditory Nerve
Action Potentials
Conduction Hearing Loss: Hearing loss caused by
damage to the mechanical system that conducts
sound waves to the cochlea.
Sensorineural Hearing Loss: Hearing loss caused by
damage to the cochlea’s receptor cells or to the
auditory nerve, also called nerve deafness.
Older people tend to hear low frequencies well but suffer
hearing loss when listening for high frequencies.
Cochlear implants are electronic devices that enable
the brain to hear sounds.
Wolfgang Gstottner. (2004) American
Scientist, Vol. 92, Number 5. (p. 437)
EG Images/ J.S. Wilson ©
Deaf Musician
Cochlear Implant
Because we have two ears, sounds that reach one
ear faster than the other ear cause us to localize
the sound.
Smell and Taste
What is the bigger question here?
Nature versus Nurture
Traditionally, taste sensations consisted of sweet,
salty, sour, and bitter tastes. Recently, receptors for
a fifth taste have been discovered called “Umami”.
Sweet
Sour
Salty
Bitter
Umami
Meaty/cheesy
Lets take a look at the Nature
perspective first.
•Taste (and smell) are
chemical senses.
What is the central muscle
involved in taste?
Those bumps on our
tongue are called
Papillae.
Papillae help grip food
while your teeth are
chewing. They also have
another special job they contain your taste
buds
Surface of the tongue
chemicals, which are the
stimuli for taste, break
down into molecules
molecules mix with saliva
an run into narrow
trenches on the surface of
the tongue
molecules then stimulate
the taste buds
Gustation: the process of tasting
SEM Taste bud on fungiform papilla, close-up
Scanning electron micrograph of close-up of a taste bud on a fungiform papilla on the
tongue, computer-coloured red./pink.
Taste buds
shaped like miniature onions
receptors for taste
chemicals dissolved in saliva
activate taste buds
produce nerve impulses that
reach areas of the brain’s
parietal lobe
brain transforms impulses
into sensations of taste
Gustatory Pathway
Figure 15.2
When one sense affects another sense, sensory
interaction takes place. So, the taste of strawberry
interacts with its smell and its texture on the
tongue to produce flavor. Taste is 80% smell.
Like taste, smell is a chemical sense. Odorants
enter the nasal cavity to stimulate 5 million
receptors to sense smell. Unlike taste, there are
many different forms of smell.
Stimulus
we smell volatile
substances
volatile substances are
released molecules in the
air at room temperature
example: skunk spray,
perfumes, warm brownies;
not glass or steel
4 Primary Odors
• acid  sour
• burnt
• fragrant  sweet
• caprylic  rancid, rotten
Not in text
Olfactory cells
receptors for smell are located in a I-inch-square patches of
tissue in the uppermost part of the nasal passages.
olfactory cells are covered in mucus
which volatile molecules dissolve and stimulate the cells
the cells trigger nerve impulses that travel to the brain
which interprets the impulses as different smells (some
10,000 or so)
Sensory adaptation don’t smell own perfume, sweat, …
Cilia: Nose Hairs
Sense of Smell
Figure 15.3
The brain region for
smell (in red) is closely
connected with the
brain regions involved
with memory (limbic
system). That is why
strong memories are
made through the sense
of smell.
Ability to identify smell peaks during early
adulthood, but steadily declines after that. Women
are better at detecting odors than men.
Can you smell the difference between?
Well….yes and no.
Pheromones
•Chemical messengers that are picked up through
our sense of smell.
•Founded in the early 1930’s by studying
silkworms.
•Jury is still out on whether they exist in humans.
Best evidence we have comes out of the
university of Chicago.
to intensify the taste of food
to warn of potentially dangerous foods
elicit strong memories; emotional feelings
Somesthetic Senses
Soma  body
Esthetic  feeling
Touch
Kinesthetic
Vestibular
Bruce Ayers/ Stone/ Getty Images
The sense of touch is a mix of four distinct skin
senses—pressure, temperature (warmth & cold),
and pain.
Only pressure has identifiable receptors. All other
skin sensations are variations of pressure, warmth,
cold and pain.
Pressure
Burning hot
Vibration
Vibration
Cold, warmth and pain
The Tactile Senses
Touch
Skin receptors that make us
aware of how & where we’re
being touched.
Pressure
Receptors beneath the skin
that make us aware of deeper
touch.
Temperature
Receptors are found just
beneath the skin to give the
sensation of hot, cold, and
warm.
somatosensory cortex
located in the parietal
lobe
Pain tells the body that something has gone wrong.
Usually pain results from damage to the skin and
other tissues. A rare disease exists in which the
afflicted person feels no pain.
AP Photo/ Stephen Morton
Ashley Blocker (right) feels neither pain
nor extreme hot or cold.
Melzak and Wall (1965, 1983) proposed that our
spinal cord contains neurological “gates” that
either block pain or allow it to be sensed.
Gary Comer/ PhototakeUSA.com
Pain can be controlled by a number of therapies
including, drugs, surgery, acupuncture, exercise,
hypnosis, and even thought distraction.
Todd Richards and Aric Vills, U.W.
©Hunter Hoffman, www.vrpain.com
Receptors located in
our skin.
Three sensations?
Touch, pressure,
temperature
Gate Control Theory of
Pain
The sense of our body parts’ position and
movement is called kinesthesis. The vestibular
sense monitors the head (and body’s) position.
Bob Daemmrich/ The Image Works
http://www.heyokamagazine.com
Whirling Dervishes
Wire Walk
Grace and Balance
The Kinesthetic Sense
Keeps us informed about
movement of body parts &
their position in relation to
each other.
Muscle Movement, Posture, &
Joints
Information comes from
stretch receptors, the tendons,
& the internal organs.
Tells us where our
body parts are.
Receptors located in
our muscles and
joints.
Without the kinesthetic sense
you could touch the button to
make copies of your buttocks.
Balance & Equilibrium
Vestibular Sense
• keeps us informed about
•
balance & the position of
our body in space.
Hair cells in the inner ear
bend in relation to the
position & movement of the
head giving information
that the brain uses to help
us maintain our balance and
to sense changes in our
movement through space.
Tells us where our
body is oriented in
space.
Our sense of balance.
Located in our
semicircular canals in
our ears.
Adapted from APPsychology.com