olfactory bulb receives input from olfactory receptors which contact mucus in nasal cavity smell
Post on 30-Dec-2015
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• Olfactory bulb receives input from olfactory receptors which contact mucus in nasal cavity
Smell
• There are thousands of different receptors for different kinds of molecules
Smell
• Pheromones are not smells• Pheromones are chemical signals sent from
one animal to another
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
Pheromones
• For example: Androstenone, found in male pig saliva, causes a female pig to allow the male to mate with her
Fun Facts about Pheromones
• androstenone is also found in the sweat of human males!
• Does androstenone (or pheromones in general) affect humans?
• Design an (ethical) experiment…
Fun Facts about Pheromones
• Kirk-Smith & Booth (1980) sprayed some of the seats in a dentist’s waiting room with androstenone
• Compared to a control condition, more women used the androstenone seat
Fun Facts about Pheromones
• Fewer men used the androstenone seat !
Fun Facts about Pheromones
• Other possible ways in which pheromones influence humans:– synchronization of menstrual cycles– mate selection - attraction to opposite major
histocompatibility complex
Pheromones
• Pheromones do not control behavior!• Human behavior is largely under top-down
influences, but may be affected subtly by pheromones
• It is unclear whether molecules such as androstenone even qualify as pheromones - they may be just like other odour molecules
Pheromones
• “It is now possible to manufacture synthetic human pheromones and such compounds are often used in research as they are relatively easy to make, convenient to store, and easy to apply.”
Pheromones
Upcoming:
Read article by Gregory for February 16th
Read chapter by Pinker for February ~28th
Vision
Seeing
• Seeing is the process of converting electromagnetic radiation into a conscious mental event
Seeing
• visual system faces many challenges– too much information– too little information– conflicting information– ambiguous information
Seeing
• too much information
Seeing
• too little information
Seeing
• Conflicting Information
Seeing
• Ambiguous information
Seeing
• We will consider two aspects of vision to explore how the brain overcomes these challenges:
– Seeing depth– Seeing in color
Seeing
• Remember that the only information the brain gets is a 2D pattern of light on each retina
Seeing
• Remember that the only information the brain gets is a 2D pattern of light on each retina
• Our rich vivid visual experience is built out of those sparse inputs!
Seeing
• Remember that the only information the brain gets is a 2D pattern of light on each retina
• Our rich vivid visual experience is built out of those sparse inputs!
• Put another way, everything your brain needs to “see” is encoded in those patterns of light energy
Seeing
• Remember that the only information the brain gets is a 2D pattern of light on each retina
• Our rich vivid visual experience is built out of those sparse inputs!
• Put another way, everything your brain needs to “see” is encoded in those patterns of light energy
• …well almost everything
• Light is an oscillation (a wave) in the electromagnetic field
Light
• What are some characteristics of light waves?
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
Properties of light
•What perceptions are associated with those physical properties?
Properties of light
•What perceptions are associated with those physical properties?–Intensity is associated (loosely) with brightness–Frequency is associated (very loosely) with color–Polarization isn’t sensed by humans (but it is by some insects and birds!)
Properties of light
Light
• The spectrum is the range of frequencies of electromagnetic waves
• The eye– curved
cornea– lens– retina– fovea– optic disk
Using Light
• Light is focused on the retina by the curvature of the cornea and the lens– Flat lens (relaxed muscles) focuses distant points
Using Light
• Light is focused on the retina by the curvature of the cornea and the lens– Accomodation: Bulged lens (muscles flexed) focuses on near points
Using Light
• Light is focused on the retina by the curvature of the cornea and the lens
• Constriction of the pupil limits how much light gets in AND reduces the amount of focusing required of the lens
Using Light
• photoreceptors transduce incoming light• ganglion cells send signals along to the brain
The Retina has layers of cells
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