Transcript Slide 1

Vision
and
Hearing
 brief intro to vision:
 most important sense?
 light energy  biochemical energy  electrical
signals
 sensation  perception
 http://www.youtube.com/watch?v=nspVjwAnGb4
The Visual Process
The Visual Process, cont.
 light travels through cornea, iris
 “image” is focused
 image is displayed on retina (reversed)
 photoreceptors on retina (125 million per eye)
 rods: dim light, no color
 cones: bright light, detail, color and b-w vision
 red, green, blue cones  any color
 middle and third layer cells
Perception of Vision
 signal travels
 optic nerve  optic chiasm  lateral geniculate
nucleus (thalamus)  primary visual cortex
 signals separated into 3 processing systems:
 1. shape
 2. color
 3. movement, orientation, spatial organization
 Perception depends on light intensity?
 not fully understood:
http://www.youtube.com/watch?v=RJmP34WRFK
U
Hearing
 sound waves
 waves  vibrations  electrical signals
http://www.youtube.com/watch
?v=7a2aoZeZhZ8
Auditory Process
Auditory Process, cont.
 Vision combines signals (wavelengths)
 Hearing separates sound waves (complex
sounds)
 sound waves collected by tympanic
membrane (eardrum)
 vibrations  malleus  incus  stapes
Auditory Process-inner ear
 outer ear
 middle ear
 inner ear (fluid)-
cochlea separates
frequencies
Auditory Process-Organ of Corti
 Pressure waves produced in cochlea
 Hair cells on basilar membrane have hair
bundles of stereocilia (stereo + cilia)
 Hair bundles deflected by tectorial membrane
 Vibration of hair bundles is converted to electrical
signal by hair cells and send to 30,000 fibers of
auditory nerve
Auditory Process-Organ of Corti
Sound Perception
 Sound travels to temporal gyrus, auditory
cortex
 Complex process
 Many sounds
 language, natural sounds, music, loud/soft,
quality, tone, pitch, length
 adjacent neurons- similar frequency
 specialized neurons respond to different tones
 pure vs. complex sounds
 Left auditory cortex-speech
 Broca’s area
PICTIONARY