Lecture 11 - The Other Senses Flashcards
Audition stimulus
- sound waves
- pitch
- loudness
- timbre
Sound waves
vibrations of an object cause air particles to vibrate (oscillations of compressed and rarefied air). (like ripples in water)
Pitch
frequency of vibration (Hz).
Loudness
intensity (more vigorous vibrations = more intense stimuli).
Timbre
complexity of sound (mixture of vibrations).
- could tell even though they are same notes they’re coming from 2 diff instruments
More waves per sec, the ____ the pitch
HIGHER
Anatomy of the ear
- sound funneled through ear canal to ear drum (tympanic membrane).
- middle ear – bones set to vibrate by ear drum.
- malleus (hammer), incus (anvil), stapes (stirrup). - connect to cochlea
- cochlea – energy transmission from middle ear to inner ear (from air to liquid).
sound waves –> mech energy –> energy in inner ear filled with liquid (physical waves of liq) going to cochlea
Auditory pathway dets
- cochlear nerve (branch of vestibulo-cochlear).
- 95% synapse with inner hair cells.
- outer hair cells are EFFECTOR cells that alter effects of vibrations on inner cells.
(depending on which hair cells in cochlea get stimuluated, we perceive diff sounds)
Auditory cortex – primary pathway
Auditory Nerve
- -> Cochlear Nuclei
- -> Superior Olivary Nucleus
- -> Auditory Cortex
- -> Medial Geniculate Nucleus
- -> Inferior Colliculus
- CONTRAlateral and IPSIlateral projections – information from the cochlear goes to both hemispheres.
- TONOTOPIC organization. - depending on vibration freq, diff parts of basilar mem. will be stimulated & vibrate – hair cells will in turn be excited & send signals to brain
Perception of pitch
PLACE CODING – DIFFERENT PARTS of basilar membrane FLEX in respond to DIFFERENT FREQUENCIES – point of maximum vibration is tightly coupled to frequency.
Perception of loudness
loudness transmitted to CNS by rate of firing (louder sounds – higher firing rate).
loudness of low frequencies signaled by number of neurons firing (because rate changes pitch in these neurons).
Perception of timbre
same note on different instruments – timbre gives the different qualities.
- get richness of music b/c of timbre
Perception of spatial location
PHASE DIFFERENCE – the difference in arrival times of sound waves at each of the eardrums. Left/right judgments are more accurate (b/c we use a race to the sup. olivar nucleus 1st) than front/back (hits at same time).
LOCATION BY INTENSITY – intensities are absorbed by the head creating a “sonic shadow”.
timing & intensity help localize sound
Association cortex and pattern recognition
What vs Where. Brain activity in response to judgments of category (red) and location (blue) of sounds.
IFG = inferior frontal gyrus, IPL = inferior parietal lobule, MFG = middle frontal gyrus, SFG = superior frontal gyrus, SPL = superior parietal lobule.
Vestibular system
semicircular canals – angular acceleration (rotation of the head). (when you move, they move - can tell direction of which way you turned your head with your eyes close)
vestibular sacs – responds to gravity.
Vestibular functions include
balance
head position
eye / head compensation (vestibulo ocular reflex)
Vestibular system
Low frequency stimulation of the vestibular sacs can cause…
NAUSEA
stimulation of canals can cause dizziness.
Vestibular system
nystagmus
– rhythmic left/right eye movements.
caloric stimulation (cold water in the ear) causes nystagmus (twitching)
Vestibular anatomy
canals approximate head planes (sagittal, transverse and horizontal).
most axons synapse on vestibular nuclei in medulla.
some direct synapses with cerebellum.
cortical connections – dizziness.
lower brain stem connections – nausea & vomiting.
Over-representation in the Motor and Somatosensory strips
Regions requiring more fine motor control (or with greater density of tactile receptors) will have larger representations in the cortex
Cutaneous senses
touch (skin receptors).
Kinesthesia
body position and movements (joints, muscles, tendons).
Organic senses
receptors in and around internal organs (butterflies in the stomach).
The Stimuli
Touch
pressure – deformation of the skin (pressing down on arm)
vibration – surface texture (touching diff senses like sand paper)
pain – tissue damage
The Stimuli
Kinesthesia
stretch receptors in muscles (info re: muscle length)
stretch receptors in tendons (info re: force)
joint receptors provide info re magnitude and direction
Skin – a vital organ!
protection (wound is opening for pathogen)
thermoregulation (sweat or restriction of circulation)
Pressing on skin =
indentation (Ruffini)
Rubbing fingers on a surface & feeling vibrations =
vibration (Pacinian)
Glabrous skin
glabrous – hairless, more complex mixture of free nerve endings and axons
- palms & bottom of feet
- good at picking up MINUTE DETS b/c of all the nerve endings they have small receptive fields
2-point test
- prongs vary on test
- you can go v. close together on fingertips for ex & still determine that is 2 separate pricks
Pacinian corpuscle
sensitive to vibration.
Large diameter myelinated axons
fast-conducting, localization of touch.
Small diameter unmyelinated axons
– temperature and pain.
Temperature perception is relative:
dependent on prior experience.
walking in a room that’s cool after being in hot/cold weather
_______ receptors closer to the surface of the skin; ____ receptors are deeper.
COOLNESS
WARMTH
Moving stimuli
dynamic interaction with kinesthetic information and motor control systems to determine, texture, density and in some instances identity.
- if you combine touch & movement you will get more info
- touch & moving hand over it to touch
Somatosensory pathways
Dorsal root ganglia
Spinothalamic tract (pain, temp)
Cross over at medulla
Connections in midbrain
Up to thalamas
Then to primary somatosensory cortex
Tactile agnosia
an inability to recognize common objects by touch not due to a loss of sensitivity (discrimination still possible).
damage to angular gyrus.
apperceptive and associative distinctions apply.
Tactile neglect / extinction
tactile neglect/extinction is normally co-morbid with visual neglect.
cross-modal attention.
Allochiria
mislocalization of touch, usually from lateral to medial within one limb but can be across limbs.
Autotopagnosia
inability to identify body parts that have been touched, finger agnosia most common.
Pain
nociceptors – receptors of noxious stimuli
intense pressure (e.g., striking)
heat, acid – capsaicin (active ingredient in hot peppers) - way to have pain relief
Sensory Pain
Sensory – intensity of a painful stimulus
- primary somatosensory pathway
Emotional Pain
Emotional – evaluation of the sensory component – past experience
- anterior cingulate and insular cortex
Long-term implications of Pain
– threat to future comfort prefrontal cortex (stimulus-response associations and long-term memory)
Sensory component of pain =
somatosensory cortex
Emotional component of pain =
anterior cingulate
Hypnotism study
somatosensory cortex NOT affected not affected by hypnotism.
- sensory comp. of pain wasn’t infected
anterior cingulate shows LESS activation during hypnosis.
- emotional comp. of pain was controlled a bit
Stimulus for olfaction:
volatile substances that rapidly vaporizes
Olfactory mucosa
mucous membrane at top of nasal cavity
less than 10% of air reaches mucosa
Bipolar receptor cells
cilia in mucosa send signals to olfactory bulb
Olfactory cortex
nasal mucosa – olfactory bulb – two pathways
pathway 1 – limbic system (amygdala, pyriform & entorhinal cortex)
pathway 2 – dorsal medial thalamus – orbitofrontal cortex (primary olfactory cortex – and much more)
bundles of axons enter through holes in skull - cibriform plate
Bundles of axons enter through holes in skull
cibriform plate
Olfactory cortex consists
- olfactory bulb
- olfactory tract
- orbitofrontal cortex
Olfactory receptors
between 500 and 1,000 different receptor types tuned to different odours
but we can recognize and distinguish between many more odours than there are receptor types
specific ODORANTS are capable of binding to more than one receptor type
different PATTERNS of binding for different odours
______ and _____ are the only senses NOT ‘crossed’ – ________ organization
OLFACTION
GUSTATION
IPSILATERAL
Damage to ______ cortex (e.g., from acceleration/deceleration injuries) can lead to ____
ORBITOFRONTAL
ANOSMIA
Anosmia is an olfactory impairment
loss of smell
difficulty distinguishing smells
In order for something to be tasteable it has to be…
SOLUBLE (have to be able to stick it in mouth & saliva has to start breaking it down)
5 qualities of taste
bitterness
sourness – as with bitterness causes an avoidance response
sweetness – usually sweet foods are safe
saltiness – system sometimes needs sodium chloride
umami
Flavour
a combination of olfaction and taste
Umami – the fifth sense
umami – Japanese word that can be translated to “beautiful taste”
the wonders of MSG! Glutamate receptors
present naturally in meats, cheeses & some vegetables
What about fats? The 6th taste?
coating of fat when eating rich ice cream - influences flavour but not taste
odour and texture - mouth feel
Gustatory anatomy
tongue, palate, pharynx, larynx
- around 10,000 taste buds
Papillae
bumps on the tongue (taste buds)
Fungiform
anterior 3rd of the tongue
Foliate
folds on the sides and back of the tongue
Circumvallate papillae
inverted V on posterior 3rd of the tongue
Receptor cells on tongue have a life span of ____ days
10-14
b/c if we burn tongue with hot food & other food can be dangerous too
Gustatory pathways
cranial nerves VII (facial), IX (glossopharyngeal) and X (vagus)
anterior buds – chorda tympani branch of VII
posterior buds – lingual branch of IX
palate – Xth cranial nerve
Primary gustatory pathway: solitary tract of medulla –> ventromedial neucleus of the thalamus (relay station that also receives information from trigeminal nerve – mastication) –> ventral frontal cortex and insular cortex
Activation in the Primary Gustatory Cortex
response regions vary between subjects but were stable for each subject.
Gustation, olfaction and conditioned learning
secondary gustatory pathways go to the amygdala and hypothalamus
convergence of taste and smell in orbitofrontal cortex
connection with amygdala and memory systems reinforces positive / negative episodes and their associations with particular smells and tastes
Taste Adversion
is a conditioned response in which a person/animal establishes an association b/t a particular food & being/feeling ill after having it in the past
the association is usually as a result of a SINGLE (UNPLEASANT) experience & the particular food will be avoided in the future
Sound can best be thought of as
A) compression of air molecules by an object.
B) changes in air pressure produced by the vibration of an object.
C) waves of acoustic energy that travel at fewer than 20 miles per hour.
D) packets of energy.
E) Expansion of air molecules produced by a traveling object.
B) changes in air pressure produced by the vibration of an object.
The primary function of the Pacinian corpuscle is to detect A) damage to the skin. B) cold. C) heat. D) texture. E) rapid vibration.
E) rapid vibration.
Olfactory receptors are located in the A) turbinate bones. B) cribiform plate. C) olfactory epithelium. D) Chorda tympani. E) Olfactory operculum.
C) olfactory epithelium.
Which of the following is true of taste/flavour?
A) Flavour is a mixture of olfaction and gustation.
B) Taste is a mixture of olfaction and gustation.
C) Flavour is determined by air temperature.
D) Flavour is solely determined by the smell of food.
E) Everyone thinks Brussels sprouts taste bad.
A) Flavour is a mixture of olfaction and gustation.
