Chapter 6 Part II - The Other Senses
I.
Touch
A.
B.
Name the four distinct sensations of touch.
1.
Pressure - mechanoreceptors
2.
Pain - nociceptors
3.
Warmth - thermoreceptors
4.
Cold - thermoreceptors
The SENSORY CORTEX is the part of your brain specialized to feel pressure
from each part of your body. (Chapter 2 Notes)
1.
Testing Pressure Points
Using a ruler and two paperclips/toothpicks, measure the pressure sensitivity of each of the areas
of your partner’s body. Measure in CENTIMETERS.
Start with the toothpicks right next to each other. GENTLY “pressure” your partner in the
following areas repeatedly until they can tell a distinction between the two. Record the space
between the two when they say. Make sure your partner closes his/her eyes to prevent top-down
processing.
2.
a.
Back (between shoulder blades)
b.
Left Calf (in the middle, not an ankle)
c.
Bottom Lip ________ cm
d.
Index Finger (pointer, at tip) ________ cm
__________ cm
MORE of your cortex is designated for places that feel pressure more distinctly
such as:
3.
_________ cm
Face, Hands
LESS of your cortex is designated for places that feel pressure less distinctly
such as:
Back, Calf, Thigh
4.
C.
D.
This test also exemplifies the DIFFERENCE threshold. Our JUST
NOTICEABLE DIFFERENCE is smaller on places where receptors are more
CONCENTRATED.
How do we feel textures?
1.
Susan LEDERMAN suggests in her theory that we feel texture based on the
ELASTICITY of our skin fibers.
a.
Which should have the most calluses?
b.
Which the least?
How do we feel pain?
1.
Pain is BOTH a part of our SKIN/ORGANS (where it is sensed) and our BRAIN
(where it is organized and perceived as “pain”).
2.
Our brain can PERCEIVE pain WITHOUT actual skin stimulation.
(phantom limb)
3.
There is NO direct ROUTE from the skin to the brain to feel pain.
4.
There are theories for why and how we feel pain.
*And how we can manage pain.
a.
GATE-CONTROL THEORY: This suggests that there is a GATE in the spinal
cord that allows pain messages to be sent to the BRAIN.
Small NERVE fibers conduct the pain signals through the spine.
Large NERVE fibers conduct other sensory signals.
Large fiber activity turns the SMALL activity off by closing the “gate” of
sensory AWARENESS through the spine.
This explains why we:
5.
How can we control pain?
a.
Our natural pain killers are ENDORPHINS.
b.
E.
Other methods:
medications (opiates), surgery, acupuncture, electrical
stimulation, massage, exercise, hypnotherapy, relaxation,
thought distraction (hypnobirthing)
Warmth and Cold
1.
If we sense Warmth and Cold only, how do we “sense” HOT?
a.
Yes, the object you’re touching IS hot. But your sensation DOES NOT come
from “hot” receptors.
o
o
o
Warm receptors stimulated alone (warm water) = warmth sensation
Cold receptors stimulated alone (cold water/ice) = cold sensation
Warm receptors stimulated SIMULTANEOUSLY with cold receptors
produces SENSATION of hot = hot sensation
II.
Taste and Smell- The CHEMICAL Senses
A.
Taste
1.
There are FIVE basic receptors for taste:
a.
SWEET
c.
SOUR
e. (attachment) UMAMI
b.
SALTY
d.
BITTER
2.
It has NOT proven that there are specific nerve fibers for each one, though.
3.
Taste is NOT specific to parts of the TONGUE either.
*
Tongue maps are NO LONGER used.
*
Receptors scattered all over tongue – except more bitter concentrated at back.
4.
How do we taste?
a.
The taste buds have pores that take in the CHEMICALS from our foods.
5.
b.
We require very LITTLE stimulation from these chemicals.
c.
We lose taste buds over time, which explains:
d.
Taste buds can be replenished, which explains: burn tongue/grow back within five days
more spices/less enjoyment of food
as we get older
How and why do we taste bitter?
a.
b.

Super:


Medium
Non
Bitter all the way through *heightened receptors/lower threshold for all
taste
Sweet then bitter (at back of tongue) *normal receptors
Sweet all the way through *higher threshold for all tastes
“Super Taster” test
Who tend to be nontasters?
Correlational – alcoholics (no aversion to bitter)
6.
Candy Experiment
a
We need our NOSE to taste the flavor of foods.
7.
What is the difference between taste and flavor?
a.
Explain:
Taste = tongue (only 5 types of taste)
Flavor = tongue AND nose (thousands)
b.
*
Name some examples of flavors:
orange/strawberry/lemon/cherry
Sensory Interaction/McGurk Effect:
The brain combines simultaneous signals (vision/hearing or taste/smell) to make each sensation heightened.
Synesthesia:
B.
For some people, the senses become JOINED, where stimulation in one produces
sensation in the other.
..\Brief Synaesthesia 60 minuts.mp4
 Seeing something produces a taste sensation
 Hearing a sound produces a sensation of color
Smell (bottom up)
1.
Smell is also a CHEMICAL sense.
2.
We smell when air molecules take CHEMICALS to a cluster of receptor cells at top of the
NASAL cavity.
Axons from these receptors band together to form our OLFACTORY NERVE and take messages
to the brain through the olfactory BULB.
3.
We recognize odors INDIVIDUALLY. Odors slip into particular RECEPTORS just like
NEUROTRANSMITTERS in a lock-and-key fashion.
4.
Odors are sent to the TEMPORAL lobe as well as the LIMBIC system, which might explain:
How emotion and memory are so tied to odor.
5.
Smell can also influence our body systems.
a.
III.
Pheromones:
o scents detected below our threshold of awareness that affect/direct our behaviors
o dogs/marking
o menstruation – menstrual synchrony
o attraction??
Equilibrium/Kinesthetic (Body Position and Movement)
A.
We all have a sense of where our BODY is in relation to the space around us.
B.
This is controlled by MOTION sensors.
C.
Our sense of the position of our body, such as our head, limbs, legs, etc. is called KINESTHESIS.
D.
These sensors are part of the VESTIBULAR system. They are located in the SEMI-CIRCULAR canals
in our inner ears.
1.
When the head rotates, FLUID in the canals moves.
2.
The movement of the fluid causes small particles called VESTIBULAR SACS to move and bend
receptors in the canals
3.
If you spin around, the sacs and fluid continue to move when you stop, giving your body the
SENSE that it is still moving in space by stimulating the HAIR CELLS.