Vision and Hearing brief intro to vision most

Vision and Hearing

brief intro to vision: most important sense? light energy biochemical energy electrical signals sensation perception http: //www. youtube. com/watch? v=nsp. Vjw. An. Gb 4

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=RJm. P 34 WRFK U

Hearing sound waves vibrations electrical signals http: //www. youtube. com/watch ? v=7 a 2 ao. Ze. Zh. Z 8

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

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