Two classes of thermoreceptors: warm and cold

1
Thermoception

• Two classes of thermoreceptors warm and cold

2
Taste (Gustation)
Taste buds contain chemical receptors
3
Taste
What are the various tastes?
4
Taste

• Multi-dimensional scaling reveals several
  varieties of tastes
• sweet
• salt
• bitter
• sour
• umami (MSG) - protein receptor?
• fat receptor?

5
Taste is Relative

• What you taste depends critically on what
  youve recently been tasting
• taste receptors adapt and reduce firing over time
• for example eating something salty reduces the
  perceived saltiness of subsequent foods

6
Smell

• Olfactory bulb receives input from olfactory
  receptors which contact mucus in nasal cavity

7
Smell

• There are thousands of different receptors for
  different kinds of molecules

8
Smell

• Olfactory receptors use a lock-and-key
  mechanism - only specific molecules will bind
  with a given receptor

Odor Molecules
Receptor
9
Smell

• Odor recognition is excellent in humans
• but odor identification (naming) is very poor
• Women tend to be (slightly) better than men at
  naming smells

10
Smell

• Smell is strongly influenced by top-down
  processes such as what you are expecting to smell

11
Pheromones

• Pheromones are not smells
• Pheromones are chemical signals sent from one
  animal to another

12
Pheromones

• Pheromones either induce a behavior in another
  animal or cause some physiological change
• Very common in insects...not so common in
  mammals...unclear role in humans

13
Fun Facts about Pheremones

• For example Alpha Androstenol, found in male pig
  saliva, causes a female pig to allow the male to
  mate with her

14
Fun Facts about Pheremones

• Alpha androstenol is also found in the sweat of
  human males!
• Does alpha androstenol (or pheromones in general)
  affect humans?
• Design an (ethical) experiment

15
Fun Facts about Pheremones

• Kirk-Smith Booth (1980) sprayed some of the
  seats in a dentists waiting room with alpha
  androstenol
• Compared to a control condition, more women used
  the alpha androstenol seat

16
Fun Facts about Pheremones

• Fewer men used the alpha androstenol seat !

17
Pheromones

• Other possible ways in which pheromones influence
  humans
• synchronization of menstrual cycles
• mate selection - attraction to opposite major
  histocompatibility complex

18
Pheromones

• Pheromones do not control behavior!
• Human behavior is largely under top-down
  influences, but may be affected subtly by
  pheromones

19
The Visual System

• What kind of energy does the visual system sense
  and perceive?

20
Light

• Light is an oscillation (a wave) in the
  electromagnetic field

21
Properties of light

• What are some characteristics of light waves?

22
Properties of light

• What are some characteristics of light waves?
• amplitude/intensity - how big of a fluctuation in
  the field/how many waves
• frequency - how many fluctuations (waves) pass by
  a certain point in a given period of time
• polarization - the orientation of the waves

23
Properties of light

• What perceptions are associated with those
  physical properties?

24
Properties of light

• What perceptions are associated with those
  physical properties?
• Intensity is associated (loosely) with brightness
• Frequency is associated (loosely) with color
• Polarization isnt sensed by humans (but it is by
  some insects!)