The Stimulus Input: Sound Waves

• Audition = hearing• Amplitude of wave

–loudness• Frequency of wave

– Pitch

Semicircular Canals

The Ear

Neural impulse to the brain

The EarPerceiving Loudness

• Basilar membrane’s hair cells–Compressed sound

The EarPerceiving Pitch

• Place theory

• Frequency theory

Place Theory

• Different hairs vibrate in the cochlea when they different pitches.

• So some hairs vibrate when they hear high and other vibrate when they hear low pitches.

Frequency Theory

• All the hairs vibrate but at different speeds.

The EarLocating Sounds

• Stereophonic hearing• Localization of sounds

–Intensity–Speed of the sound

Demonstration volunteer

DeafnessConduction Deafness

• Something goes wrong with the vibrations of sound on the way to the cochlea.

• damage to parts of the ear itself

• You can replace the bones or get a hearing aid to help.

Nerve (sensorineural) Deafness

• The hair cells in the cochlea get damaged.

• Loud noises can cause this type of deafness.

• NO WAY to replace the hairs.

• Cochlea implant is possible.

Cochlea and loud sounds

Hearing Disorders• About 28 million people have some form of hearing damage

in the U.S.• Can be caused by

– Injury– Infections– Explosions– Long-term exposure to loud noises

• Conduction hearing loss results from damage to parts of the ear itself

• Sensorineural hearing loss results when there is damage to hair cells or auditory nerve

• Cochlear implants can replace damaged hair cells and transduce sounds into electrical signals sent to the auditory nerve– Use of the implants is debated– Many advocates for the deaf argue that deafness is NOT a

disability, but rather an enhancement of other senses

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Touch Our largest organ is ___________________ Hairy skin: contains hair cells which detect movement and pressure Glabrous skin: no hair cells; hands, feet, lips; more sensitive

Bottom- up processing

Evidence of top-down processing

Hard to tickle yourself Rubber hand illusion (next slide)

The Skin Senses

• Skin is the largest sense organ• There are receptors for

pressure, temperature, and pain

• Touch appears to be important not just as a source of information, but as a way to bond with others

• Homunculus Man– Proportional representation of skin

receptor concentration– The larger the part, the more

receptors/the more sensitive– Demo: Skin sensitivity

• “Paradoxical heat”

Remember Me?

How do we feel?

• Composed of four senses: warmth, pain, cold, pressure (the only one with identifiable receptors)

• Warm + cold = hot• Pressure + cold= wet• Pressure + pain= tickling itch

Touch

• Rubber hand illusion

Kinesthesis

Tells us where our body parts are.Receptors located in our muscles and joints.

Sense of position and movement of your body’s parts based on sensors in your joints, tendons, bones, ears and skin.

Interacts with vision (demonstration heel to toe)

What would life be like if you lost this sense?

Vestibular sense

Based on activity in your inner ear (semicircular canals and vestibular sacs)Tells us where our body is oriented in space.Our sense of balance.Located in our semicircular canals in our ears.

What happens when you spin around repeatedly? Why do we feel dizzy?

Vestibular Senses• Vestibular senses provide

information about equilibrium and head and body position– Fluid moves in two

vestibular sacs and the semicircular canals

– These vestibular organs are lined with hair cells that bend when fluid moves over them

• Vestibular organs are also responsible for motion sickness

• Motion sickness may be caused by discrepancies between visual information and vestibular sensation

The pain circuit

PainUnderstanding Pain

• Biological Influences– Noiceptors - sensory receptors for pain– Gate-control theory

Ron Melzack and Patrick Wall in 1962, is the idea that physical pain is not a direct result of activation of pain receptor neurons, but rather its perception is modulated by interaction between different neurons.-helps explain how acupuncture and electrical stimulation works. Also, why rubbing a stubbed toe helps relieve pain.

– Endorphins - body’s natural morphine– Phantom limb sensations

Phantom hearing, also phantom sights and phantom tastes

Phantom Limb Sensation

• The brain can misinterpret the spontaneous central nervoussystem activity that occurs in the absence of normal sensory input.• Phantom limb pain is the • feeling of pain in an absent limb or a • portion of a limb

Pain• Serves as a warning about

injury or other problem• Large individual differences in

pain perception• Gate control theory

– Neurological “gate” in spinal cord which controls transmission of pain to brain

– Major pain signals (large fiber activity) can close “gate” while small ones open it

• Biopsychosocial theory– Holds that pain involves not

just physical stimulus, but psychological and social factors as well

• Placebo effect– Shows that when a person

believes a medication reduces pain, their pain is often reduced even though no medication was given

– Pain relief is likely the result of endorphin release

• Alternative approaches– Hypnosis and Self-hypnosis– Acupuncture– Thought distraction

Controlling Pain

• If you rub or shake your hand after you bang your finger, you stimulate large fibers (normal somatosensory input to the projector neurons). This closes the gate and reduces the perception of pain.

Pain is weird and we don’t understand it completely

• Do Now: Why would it be bad not to feel pain? Do you think people who don’t feel pain have normal life expectancy? Why or why not?

• Nociceptors – respond to hurtful pressure, temperature and chemicals

• Placebos can relieve pain. So can hypnosis, biofeedback, physiotherapy, ultrasound, acupuncture, relaxation, electrical stimulation and massage.

PainUnderstanding Pain

• Psychological Influences–Rubber-hand illusion–Memories of pain

PainUnderstanding Pain

• Social-Cultural Influences

Biopsychosocial approach to pain

Gate controltheory

Taste

• Sweet, sour, salty and bitter–Umami

• Taste buds–Chemical sense

• Why are baby’s fussy with food?

Taste

• Five Basic Tastes• 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(Fresh [dead?]

Chicken)

I Jade!

Taste• Receptor cells are

located in taste buds

• Taste buds are located in papillae (“pa-PILL-ee”) on the tongue

• Chemicals dissolve in saliva and activate taste receptors inside the taste buds

• Taste is processed in the parietal lobe

Taste• Why do we have

receptors for the tastes we do?

• Evolutionary perspective on how taste receptors developed?

• Other aspects of taste result from the interaction of taste and smell together, such as flavors.

• Without a sense of smell, our ability to distinguish flavor vanishes!

Smell

• Detecting common odors– Odorant binding protein

(OBP) is released and attached to incoming molecules

– These molecules then activate receptors in the olfactory epithelium

– Axons from those receptors project directly to the olfactory bulb

• Women have a better sense of smell than men

• Anosmia– Complete loss of the

ability to smell

Smell, Taste and Memory

• 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.

Smell (olfaction)