PSYC 2: Biological Foundations -
Fall 2012 - Professor Claffey
Notes: Other Senses
History:
10/26/12 - Changed formatting (no content changes)
10/21/12 - Original posted version
Hearing
Sound
a wave of air pressure
amplitude of the wave - ______________
frequency of the wave - ______________ (with some caveats)
complexity (how many frequencies) - ______________
natural sounds are made up of many different frequencies
Ear
tympanic membrane (ear drum) - ___________________
ossicles - small bones
cochlea - ________________
organ of Corti - ______________________
organ of Corti:ear as _____________:eye
semicircular canals
vestibular system
direction & intensity of head movements
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Source:
http://www.oup.co.uk/oxed/children/oise/pictures/light/earhaircells/
basilar membrane - hair cells mounted here
tectorial membrane - rests on hair cells
shearing force on hairs cause
increased firing in auditory nerve
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higher frequencies closer to the oval window (beginning)
tonotopic organization - by ________________
Auditory pathways
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cochlea ->
auditory nerve ->
hindbrain ->
cochlear nuclear - input from only one
ear
(From here on input from
one/both
ears)
superior olives - sound localization
thalamus
medial geniculate nucleus
primary auditory cortex |
Localization of sound
Source:
http://www.audiosonica.com/en/wikipedia/Sound_localization
(you don't need to memorize the anatomy, but you do
need to understand the principle)
medial superior olives - responds to differences in
________________ of sound arrival
lateral superior olives - responds to difference in
________________ of sound arrival
these differences can be used to triangulate the source of the
sound relative to the observer
superior colliculus (SC)
deep layers - contain a "map" of the external
world
include auditory inputs
electrical stimulation to SC can produce
attention shifts, saccades, arm reaches, head turns, body turns
(rats/fish/birds),
tongue strikes (frogs),
fang-strikes (snakes)
Auditory Cortex
primary auditory cortex - inside (medial) temporal lobe
functional columns organized by frequency
secondary auditory cortex - outside (lateral) temporal lobe
pathways leaving the auditory cortex
anterior auditory pathway - towards prefrontal
cortex - ________ a sound is
posterior auditory pathway - towards parietal
lobe - __________ a sound is
posterior parietal cortex
neurons in monkeys that respond to both vision
and sound
integrating vision and hearing
Audition is not as well understood as vision
Damage
Lesions to auditory cortex = only temporary deafness
Long term problems with sound localization and
pitch differentiation
damage to ossicles = ______________ deafness
damage to cochlea or auditory nerve = ______________ deafness
loss of hair receptors
characteristic of age-related hearing loss
perception of ringing ("ringing in the ears") = ______________
cutting auditory nerve from ringing ear doesn't
eliminate ringing
may originate in the central nervous system
cochlear implant
useful if cochlear hair cells are damaged
electrodes implanted into cochlea
online videos:
http://www.youtube.com/results?search_query=cochlear+implant+hearing+for+the+first+time
Source:
http://www.daviddarling.info/childrens_encyclopedia/Health_Revolution_Chapter5.html
Somatosensory system
somatosensory - sensations of the body
stereognosis - identifying objects by touch
Cutaneous Receptors
principle
fast versus slow adaptation
fast are necessary for quick responses but,
without adaptation, would be overwhelmed by continuous stimuli
slow are necessary for background information
about continuous stimuli
Mechanoreceptors
1. free nerve endings
neurons with no specialized structures
2. Pacinian corpuscles
largest and deepest
adapt rapidly
respond to vibration (surface texture),
sudden skin indentation
do not respond to constant pressure
large receptive fields
3. Merkel's disks
adapt slowly
respond to fine skin indentations
small receptive fields
4. Ruffini endings
adapt very little
respond to skin stretch and joint
displacement (gripping)
(you don't need to memorize
which is which, but understand the kinds of stimuli,
adaption rates, and differences in receptive fields)
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Thermoreceptors
detect changes in ______________
typically free nerve endings (not specialized structures)
different receptors for detecting heat and coolness
Nociceptors
noci = ______________
detect stimuli that could be damaging to tissue
receptors for: extreme temperature, skin deformation, skin
incision, chemicals (capsaicin)
fast & slow conducting channels - immediate and chronic pain
Somatosensory Pathways
dermatomes
nerves from cutaneous receptors enter the
dorsal route of the spinal cord
areas of the body that carry information to the
same segment of the spinal cord are called dermatomes
1. dorsal-column medial-lemniscus system
information about ____________________
spinal cord -> ventral posterior nucleus
(thalamus) ->
primary/secondary
somatosensory cortex or posterior parietal cortex
3 neurons from toe to cortex
2. anterolateral system
information about ____________________
3 different tracts to different areas of the
brain
lesions of spinothalamic tract reduce
sensitivity to __________
lesions of spinoreticular tract relieves
______________
Somatosensory Cortex
Source:
http://www.mcgill.ca/about/history/more-history/firsts/1950
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Source:
http://www.isis-robotics.com/en/references.html
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1937 - Dr. Wilder Penfield electrically stimulates the cortex of
patients
finds an area that produces sensations through
out the body
somatosensory cortex
______________ organization
areas of the body that are close together are
represented close together in the brain
like retinotopic and tonotopic
somatosensory _______________
a "little man", or
representation of the body in the somatosensory cortex
larger areas of cortex
dedicated to areas of the body with greater sensitivity
Source: http://brainmind.com/BrainLecture8.html
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Source: http://daphne.palomar.edu/
rmorrissette/physio/studentwebpages/
2006spring/phantom%20pain/
web%20page.htm
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contralateral input to primary somatosensory cortex
the _______ side of the brain receives input
from only the _____ side of the body (and vice versa)
secondary somatosensory cortex
just ventral to primary somatosensory cortex
receives input from both sides of the body
receptive fields
excited by stimulus to a given area on the body
inhibited by stimulus to the surrounding areas
cortical organization
columns (moving down from the surface) - all
neurons tend to respond to same area of body
strips (moving across the surface) - different
stimulus types: touch, temperature, pain
posterior parietal cortex
receives information from both primary and
secondary cortex
we already learned: also receives input from
visual and auditory cortex
contains __________ neurons that response to
two senses, like vision/touch
for a given neuron, the visual field "moves" to
stay with corresponding part of the body
case study: W.M. - using your hand to improve
visual attention
this area of the brain __________ information
for different senses
Damage / Pathologies
astereognosia
the inability to recognize objects by touch
asomatognosia
failure to recognize part of one's body
usually from damage to right posterior parietal
lobe, affecting left side of body
Pain
a protective adaptation of the body
no single stimulus for pain
"no obvious cortical representation"
anterior cingulate cortex (ACC)
may be associated with the emotional reaction
to pain
ACC responds to many non-pain situations, such
as error detection and conflict
periaqueductal gray (PAG)
electrical stimulation causes pain blocking
effects
contain receptors for opiods (morphine)
endogenous ___________ (pain killers)
endorphins & enkaphalins
__________ pain
originating in the central nervous system
no obvious cause
cutting the nerves from source does not help
reported "source" may even be an amputated limb
- phantom limb pain
Chemical sense
the "oldest sense"
even single cell bacteria can sense chemicals
in their environment
____________ - smell, detecting chemicals in the air
_________ - taste, detecting chemicals in the oral cavity
___________ - the combination of smell and taste
____________ - chemical signals to other members of the species
Olfactory System
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chemicals are detected by
receptors on the membrane
of dendrites in the nose
humans have _________ distinct receptor proteins
neurons typically have a single
receptor type
odors activate multiple receptors
olfactory pathway
receptors ->
olfactory bulb ->
inputs are grouped by
similar receptor type
piriform cortex / amygdala ->
~primary olfactory
cortex
retinotopic, tonotopic, somatotopic -> smellotopic?
no known principle for how odors are
organized across
olfactory bulbs (no such thing as
"smellotopic")
______________ - the birth of new neurons
olfactory receptors are replaced every
few weeks
grow axons to the correct place in
olfactory bulb
one of the few brain areas with
noticeable neurogenesis
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Interesting Findings
"Women who correctly picked out their roommate’s scent scored
higher on tests of emotional sensitivity" (
Chen,
Psych Science)
Women can detect genetic differences by smell
Men (the "stimuli") were profiled for their
genetic similarity to the women in the study (the subjects)
If men were: highly similar - not
as attractive
somewhat different - attractive
highly different - not
as attractive
Might be selecting for an adaptive or "healthy"
difference in genes
"When a person looks at a photograph of a rose while smelling rose
oil, for example, she rates the aroma as both more intense and
more pleasant than she does if she smells rose oil while looking
at a picture of a peanut." (
Lundstrom)
"When she wore a perfume of floral and spice notes, the men judged
her to weigh about 4 pounds less, on average" (
Hirsch)
Gustatory System
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___________ - clusters of
approximately 50 taste receptors
taste receptors
do not have axons
many taste receptors pool to an output
neuron
33 receptor proteins identified
conventional tastes
1. sweet - ______________, 2 known
receptors
2. sour - _____________, influence ion
channels directly
3. bitter - 30 known receptors
4. salty - __________, influence ion
channels directly
5. unami - ____________, 1 known
receptor
pathway
leave tongue along 4 different nerves
->
(thalamus) ventral posterior nucleus
->
primary gustatory cortex (near
somatosensory cortex) &
secondary gustatory cortex (inside
lateral fissure)
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Copyright 2012 - Michael Claffey