Vision Flashcards
Hue
dimension of colour determined by wavelength of light
Intensity
amount of energy in a wave determined by amplitude
Pupil
adjustable opening in the center of the eye
Iris
ring muscle forming the coloured portion of eye around pupil controlling size of pupil
Lens
transparent structure behind pupil that changes shape to focus images on the retina
-controlled by ciliary muscles
Sensetivity
ability to detect the presence of dimly lit objects
Acutiy
ability to see the details of objects
Accomodation
process by which the lens changes shape to help focus near or far objects on the retina
Retina
light sensitive inner surface of eye containing rods and cones plus layers of neurons that process visual info
Binocular disparity
the difference in the position of the same image on the 2 retinas
-greater for objects closer than far
Scotopic vision
rod mediated vision
- peripheral retina
- black white and grey
- low light
Photopic vision
cone mediated vision
-colour and fine detail (high acuity)
-center retina
well lit
Optic nerve
carries nerve impulses from eye to brain
Blind spot
where optic nerve leaves eye creating a spot where there are no receptor cells
Completion
retina extracts info about image and sends it to cortex where the perception of the image is created from partial info
Fovea
- central point of retinas made up of only cones
- high acuity vision
- thinning of ganglion cells reduce distortion of light
Amacrine and horizontal cells
specialized for lateral communication
Retinal ganglion cells
some have on/off receptors fields or are selective to uniform illumination. orientation, motion (simple and complex)
Lateral geniculate cells
have receptive fields that are sensitive to one or more….. orientation, motion, direction of motion
Saccades
quick eye movements
-if there is a stable retinal image you will see nothing
Transduction
conversion of one form of energy to another
Visual transduction
light energy to neural signals by visual receptors
More cortex is devoted to areas of high ________
acuity
Magnocellular layers
input from rods
bottom 2 layers of LGN
responsive to movement
Parvocellular layers
input from cones
top 4 layers of LGN
colour, detail, slow objects
Receptive field
the area of the visual field within which it is possible for a visual stimulus to influence the firing of a given neuron
Similarities of receptive fields in retinal ganglion, LGN, and lower layer IV of striate cortex
- receptive fields of foveal areas are smaller than those in periphery
- circular fields
- monocular
- center surround organization (excitatory and inhibitory area separated by circular boundary)
Diffusely illuminating an entire receptive field will have ______ effect on firing
little
Ocular dominance
responds more robustly to stimulation of one eye more than the other
