Sensory System
Sensory channels
• Discriminative: spatial and temporal
localization of events
• Affective: pain and positive emotional
experiences
monitoring internal and external environment
Multisensory Experiences
• Interconnecting networks
• Most information as quickly as possible
• Must integrate that information
• Experiment 1: flavors of liquid
• Experiment 2: jellybean flavors
Experiment 1
• Observe the liquids, record your hypotheses in the table.
• Place a cut straw into cup A.
• Put a finger on the exposed end of the straw, trapping liquid in the straw.
• Open your mouth, placing the straw over your tongue, and release your
finger from the top of the straw. Do not allow the straw to touch your
tongue.
• Taste the solution and write down the flavor in the table.
• Use a different straw for each solution, repeating the same procedure for
each liquid.
Experiment 2
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Obtain a jelly bean
Record your hypothesis about the flavor
Hold your nose, eat the bean. Record taste.
Release your nose, what do you taste now?
Receptors
• Specialized area of a sensory neuron that
detects a specific stimulus.
5 types:
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Chemoreceptors
Thermoreceptors
Mechanoreceptors
Photoreceptors
Nocioceptors
Stimulus
5 types:
• Chemoreceptors: changes in chemical
concentrations
• Thermoreceptors: changes in temperatures
• Mechanoreceptors: changes in pressure or
movements of body fluids
• Photoreceptors: light energy
• Nocioceptors: tissue damage or distension
associated sense(s)…
Experiment 3
• Peppermints
• Sour patch kids
• Hold nose, eat, record flavor
Sensation
• Conscious awareness of incoming sensory
information
Perceiving a Sensation
• Stimulus  receptor  sensory nerve 
special area of brain
Aristotle Illusion: Experiment 4
• Cross your middle finger over your index
finger.
• Place a marble on the table top and place the
pads of your crossed fingers on top of the
marble.
• Look away from your hands, and then slightly
roll the marble back and forth in the crevice of
your crossed fingers.
• Record your findings and answer questions.
Experiment 5: wooden dowel tapping
• Follow instructions as given
Aristotle’s Illusion
• Usually fingers aren’t crossed when
manipulating objects
• Brain doesn’t account for it – felt two marbles
Dowel Rods
• Sense of touch not altered – perception was
• Harder to tell which was tapped first when
crossed arms
• Both crossed (arms and dowel rods) – easier
to tell which one was tapped first.
Both activities
• Illustrate a limitation to PERCEPTION of sense
of touch.
• you are “hardwired” for “normal” operating
circumstances
Experiment 6: vinegar
• Follow procedure as given
Adaptation
• If a receptor is continuously stimulated, sends
fewer signals to the brain.
• Why would this be advantageous?
• Receptors vary in ability to adapt:
– Pressure and touch: rapid
– Nocio- not at all
– Body position and blood chemistry – slow
Projection
• Process by which the brain, after receiving a
sensation, refers that sensation back to its
source.
 pain
General Senses
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Pain
Touch and pressure
Temperature
Proprioception
Pain: main triggers
• Tissue injury – releases particular chemicals
• Oxygen deficiency – heart attack and admin of
oxygen
• Stretching or deformity of tissue – mechanical
rather than chemical (bloating/distention)
Referred pain – shared sensory
pathways
Pain medications – how do they work?
Touch and Pressure
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Tactile receptors
Mostly on skin
First sense to develop in utero
Essential to growth and development
Kangaroo care
• Skin to skin contact from early on
• Warmth and physical contact
• Causes neurobiological changes:
– Calming
– Stabilizing temperature
– Improve feeding
 Failure to thrive
Temperature
• Scattered widely throughout body, many in
skin
• Cold: 10oC – 25oC (50oF – 76oF)
• Heat: 25oC – 45oC (76oF – 112oF)
• Pain receptors stimulated on either end of
scale
• Adapt quickly
People from Phoenix…versus people
from Chicago…
Experiment 7
• Cooling effect of menthol?
– Halls (or any cough drop with menthol)
– Drink a hot beverage – do you know its hot?
Proprioception
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Sense of orientation/position
Knowing where your body is in space
Can locate a body part without looking at it
Essential role in maintaining posture and
coordinating body movement
proprioreceptors
• Located in muscles, tendons, and joints
• Also in inner ear (for equilibrium)
• Cerebellum receives messages (coordinating
skeletal muscle activity).
• Movement and position info sent to parietal
lobe of the cerebrum
Finding Fingertips
• Close your eyes and raise both hands above your
head
• Keep the fingers of your left hand completely still
• With your right hand, quickly touch your index
finger to your nose, then quickly touch the tip of
your thumb of your left hand (with your right
index finger).
• Quickly repeat the entire process attempting to
touch each fingertip.
• Switch hands and try again.
“X” marks the spot
• Mark an X on a piece of paper.
• Pencil in hand, raise your hand above your
head, close your eyes, and make a dot as near
as possible to the X.
• Open your eyes and check your success.
• Repeat several times.
• Try it with the other hand.
Handwriting Analysis
• Lined sheet of paper, write proprioception.
• Place your pencil on the same line next to the
written word, close your eyes, and write
proprioception again.
• You can try it again and see if you improve.
• You can try it again with your nondominant
hand.
Special Senses
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Smell: olfactory cortex
Taste: gustatory cortex
Sight: visual cortex
Hearing: auditory cortex
Balance: cerbellum