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PSYC 375: CHAPTER 9

How Do We Sense, Perceive & See The World? {Exam 2 2/4}
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What are sensory receptors?
- specialized cells that transduce (convert) sensory energy into neural activity 
What are the parts of the sensory systems:
- Light: where light energy is converted to chemical {producing action potentials} - Auditory:...
What is a receptive Field?
- region of the visual world that stimulates a receptor cell/neuron
What is optic flow?
- a stream of visual stimuli that accompanies an observer's forward movement through space 
What is auditory flow?
- changes in sound heard as a person moves past a sound source or vice versa
What do both the auditory and optic flow tell us?
- it tells us how fast we are going - the direction in which we are going  - and whether...
What is receptor density?
- it is important in determining the sensitivity of a sensory system - our sensory systems...
What is the neural relay
- this is where all receptors connect to the cortex through 3-4 intervening neurons - most...
How do sensory signals encode the features of particular sensations?
- the presence of a stimulus can be encoded as an increase/decrease in a neuron's firing...
what are sensory signals coded as?
- as incoming sequences of action potentials to the CNS 
How do action potentials code the different kinds of sensations? (ex. vision vs. touch)
- different sensations are processed in different cortical areas - learn to distinguish senses...
What is syntesthesia?
- mixing of the senses - Ex. when you can "feel" sounds - Ex. like nails on a chalkboard
What is the Topographic Map?
- spatially organized neural representations of the external world. - how most mammals represent...
What is sensation?
- the registration of physical stimuli from the environment by the sensory organs
What is perception?
- subjective interpretation of sensations by the brain - how we interpret what we see 
What is the retina?
- the light-sensitive surface -- backing of your eye  - it consists of neurons and photoreceptors  -...
How does the eye work?
- as light enters, it bends by the cornea, travels through the pupil, and bends again by the...
What is the opening where the blood vessels enter in the eye
- the optic disk {aka. blind spot}
What are the 2 types of optical errors of refraction?
- it's when the lens doesn't bend as much as it's supposed to, and the light just...
What is myopia?
- nearsightedness  - the inability to see things far away - light is undershot and doesn't...
What is hyperopia
- farsightedness - inability to focus on near objects - light is overshot so it goes past the...
What is the Fovea?
- the region at the center of the retina that specializes in fine detail - this is also where...
What is the blind spot?
- region of the retina (optic disk) where axons form into the optic nerve and leave the eye  -...
What are 2 conditions of the blind spot?
- Papilloedema: swelling of the disk caused by cranial pressure - optic neuritis: inflamation...
The difference between rods & cones?
Rods - more in numbers - sensitive to light -- good for night vision  - black & white  Cones -...
What happens when light hits the photoreceptors?
- it triggers a chemical reaction that leads to the change in membrane potential  - the...
What are the 4 types of retinal-neurons?
- bipolar cell: receives input from photoreceptors  - horizontal cell: links photoreceptors...
What are the 2 types of retinal ganglion cells?
- magnocellular cell (M cell) - parvocellular cell (P cell) 
What is the magnocellular cell?
- receives input mainly from rods - sensitive to light and moving stimuli {not color though} -...
What are parvocellular cells?
- Receive input from cones - sensitive to color differences and form - found ONLY in the retina -...
What is the Optic Chiasm?
- junction of the optic nerves from each eye 
Explain the crossing over & visual pathways
- axons from the nasal retina cross over to the OPPOSITE side - axons from the temporal retina...
What is the dorsal visual stream?
- pathway that originates in the striate cortex and projects to the PARIETAL lobe. - the HOW...
what is the ventral visual stream?
- The pathway that originates in striate cortex and projects to the TEMPORAL lobe  - the...
How many layers does the striate cortex have>
six. {I to V}
what do each of the 6 layers of the LGN do?
- layer 2, 3, 5: receive fibers from the ipsilateral eye (eye on the same side) - layer 1,...
Which layers do P cells go to?
- layers 3-6 because they are responsive to color and fine detail
Which layers do M cells go to?
- layers 1-2 because it controls info processing  about movement. 
What is the tectopulvinar Pathway
M cells -> Superior colliculus -> pulvinar 
What are the 2 major divisions of the pulvinar
- medial pulvinar: which sends connections to the parietal lobe - lateral pulvinar: which sends...
what is the primary visual cortex?
- receives input from the LGN
what is the extrastriate cortex?
- the visual cortical areas outside the striate cortex 
Explain the heterogeneity of V1
- blobs: region in striate cortex that contains color-sensitive neurons - interblob: regions...
explain the heterogeneity of V2
- thick stripes: receive information from movement sensitive neurons - thin stripes: receives...
explain the left and right visual lobe
region of the visual world that is seen by your eyes - left visual lobe: right hemisphere -...
What is the on-center cell?
- when light falls onto the central circle
What is the off-center cell?
- where the lights fall on the periphery of the central circle. 
What is the luminance contrast
-the amount of light reflected by an object relative to its surroundings. 
What is stimulus equivalence 
recognizing that an object is the same across different viewing orientations - so even if you're...


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