Lec 4: Visual Processing Flashcards
1
Q
neural pathway of audition
A
- sound waves arrive at outer ear and enter auditory canal and in the canal the sound waves are amplified
- waves hit the tympanic membrane (eardrum) and make it vibrate
- low-pressure vibrations travel through middle ear and rattle three tiny bonds, which cause a second membrane to vibrate
- second membrane is the “door” to the cochlea (fluid-filled) and within cochlea there are hair cells that are the sensory receptors of the auditory system
- location of hair cell on the basilar membrane determines the sound frequency it responds to
- hair cells are mechanoreceptors, when deflected by the membrane, gated ion channels open in the cells with that K+ and Ca_ to go into cell
- if depolarized enough, it will release transmitter into synapse between hair cell and an afferent nerve
- deflection of the hair cells is converted into a neuronal signal
2
Q
sensation
A
- transduction
- physical process of taking energy from the environment and turning it into a neural signal
3
Q
perception
A
brain interpreting the neural signals from sensation
4
Q
retinal implant device
A
- solution to a detaching retina that can cause blindness in the eye
- mimics what the retina typically does
- it transmits light info the brain in place of the retina
5
Q
optic chiasm
A
- where peripheral vision crosses
- speculated that crossing is to simplify visual processing
- allows all info from the left visual field to come together in the right hemisphere and info from the right visual field to come together in the left hemisphere
- damage to the chiasm would cause tunnel vision
6
Q
retina
A
- captures light info and sends it to the brain
- layer of neurons on the back surface of the eyes
- contains photoreceptors and ganglion cells
7
Q
rods
A
- enable vision in low-light conditions
- found in periphery of the retina and not in the fovea
- many rods connect to one ganglion cell
8
Q
cones
A
- concentrated in the fovea
- require higher level of light to activate, better for daytime vision
9
Q
Retina to the CNS
A
-rods and cones are connected to bipolar neurons that synapse with the ganglion cells
- axons of the cells form the optic nerve that transmits the info to the CNS
- before it is shipped, processing occurs to converge the info
10
Q
ganglion cell
A
- type of neuron in the retina
- receive input from photoreceptors and intermediate cells in the retina and send axons to the thalamus and other subcortical structures
- consolidate info from photoreceptors so there are fewer neurons carrying the info
11
Q
cortical blindness
A
- inability to consciously see
- caused by damage to entirety of both occipital lobes
- not due to an eye issue but to do cortical (brain) injury
12
Q
retinotopic mapping
A
- map of world on the occipital lobe (visual cortex)
- reflects what the retina has captured
- injury to this map results in a scotoma (blind spot) to that location
13
Q
color processing centre (V4)
A
- cones capture colour info
- specific area of the occipital lobe that is activated with colour
- analyzes the colour of what you are seeing
- activated when an object has both the correct colours and false colours
- involved in colour constancy: brains ability to recognize a colour hasn’t changed even when the conditions do (ie. room gets darker)
- more active if paying particular attention to something’s colour
- upper and lower parts of visual field activate diff. parts of the V4
- location of where colour occurs in space matters for the V4
14
Q
cerebral achromatopsia
A
- loss of color vision due to damage in the brain
- almost always caused by stroke, extremely rare to be born with this
- can also have specific damage that causes specific parts of the field to be impaired
15
Q
cerebral akinetopsia
A
- person is unable to perceive motion in their visual field
- very rare
- usually associated with damage to both temporal lobes
- does not usually occur with damage to V5 on only side
