Psych 330 Vision & Audition
Terms
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- Wavelength
- Discriminate between to distinguish colors
- Hue
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Dominant wavelength
"Color" we perceive - Brightness
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Intensity of a color
Dark to light - Saturation
- Different shades of the same color
- Retina
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Light sensitive surface on the back of the eye consisting of neurons and photoreceptor cells: rods and cones.
Transduction occurs here - Rod
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Cylindrical, responsive to a wide range of color
Mainly night vision
Specialized for motion - Cones
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Tapered outer segment, more numerous in fovea
Highly responsive to right light, mainly day vision
Maximal responsive to specific light: blue (short). green (middle), red (long) - Fovea
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Center of the retina where photoreceptors are more densely packed
ONLY CONES - Transduction
- Light (photons) cause rods and cones to generate graded potentials eventually causing ganglion cells to fire and action potential.
- Photoreceptor
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(Rods and Cones)
Convert light energy first into chemical energy and then into neural energy - Photoreceptors are connected to two layers of retinal neurons
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Bipolar Cells
Horizontal Cells: link photoreceptors to bipolar cells
Amacrine Cells: link bipolar cells with retinal ganglion cells - Retinal Ganglion Cells
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M (magnocellular): Found throughout retina
P (parvocellular): Found largely in the region of the fovea where we are sensitive to color and fine details - Optic Disc
- Where blood vessels enter the eye and the axons that form the optic nerve leave the eye, has no receptors and this forms a blind spot.
- Optic Nerve
- Conveys information from the eye to the brain
- Optic Nerve/Tract
- Axons that run from the retina to the LGN to visual striate cortex (VI)
- Geniculostriate System
- A pathway formed by the P and M ganglion cells. This pathway goes from the retina to the lateral geniculate nucleus (LGN) of the thalamus and then to layer IV of the primary visual cortex in the occipital lobe.
- Soundwave
- Vibrations from the air to your ear turned to sound
- Transduction (Auditory)
- Converts pressures into a mechanical signal into electrochemical neural energy
- Pitch
- Frequency- the shorter the wavelength, the higher the frequency and the higher the pitch of the sound.
- Amplitude
- Height of the wave. Measured from the base to the peak or base to trough
- Timbre
- Quality of a sound independent of its pitch and volume
- Outer Ear
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Collects sounds from the environment and funnels them through the auditory system. Composed of three parts:
-Pinna: (Ears) skin covered cartilage, lowest portion is called the lobe
-External Auditory Canal: Passageway in the temporal lobe that begins at the ear and extends inwards and upwards. Lined with skin, hair and ceruminous (ear wax).
-Tympanic Membrane/ Ear Drum: Marks the border between the outer ear and middle ear. The eardrum serves as a transmitter of sound by vibrating in response to sounds traveling down the external auditory canal, and beginning sound conduction in the middle ear. Consists of three layers: The middle point of the tympanic membrane (the umbo) is attached to the stirrup, the first of three bones contained in the middle ear. - Middle Ear
- Transmits sound from the outer ear to the inner ear. Can be thought of as a room, the outer wall contains the tympanic membrane. The back wall, separating the middle ear from the inner ear has two windows: the oval window (inner ear) and the round window (Cholea)
- Ossicles
- Three tiny bones in the middle ear form a chain which conducts sound waves from the tympanic membrane (outer ear) to the oval window (inner ear). Three bones are the hammer (malleus), the anvil (incus) and the stirrup (stapes). These bones are connected and move as a chain might, causing pressure at the oval window and the transmission of energy from the middle ear to the inner ear. Sound waves cause the tympanic membrane to vibrate, which set up vibrations in the ossicles, which amplify the sounds and transmits them to the inner ear via the oval windows.
- Cholea
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(Latin for "snail") ROUND WINDOW
The site of the sense organs for hearing. Filled with fluid and contains three parts:
-The nerve hair cells
-The tectoral membrane
-The basilar membrane - Organ of Corti
- Lies along the entire length of the basilar membrane. The organ contains hairs (cilia) and is the site of the conversion of sound waves into nerve impulses, which are sent to the brain, for auditory interpretation.
- Cilia
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Hair cells have hair like structures
-Outer: Embedded into tectoral membrane; amplify/ increase clarity of the sound
-Inner: Loosely connected; necessary for hearing - Tectorial Membrane
- Covers the surface of the organ of corti
- Tip Link
- Opens and allows influx of potassium channels causing depolarization of the membrane. Neurotransmitters are released to the dendrites of auditory nerve fibers
- Primary Auditory Cortex (AI)
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In temporal lobe. tonotopic "sound space" representation
-500 Hz corresponds to apex of cochlea
-16,000 Hz corresponds to the base of the cochlea