Vision Flashcards
Where does the first stages of visual processing occur?
Retina
What is retinal projection?
Small, inverted 2D image distorted by the curvature of the eye
What are specialised for day vision?
Cone cells
What are specialised for night vision?
Rod cells
What is opsin?
Light sensitive protein in membrane go photoreceptors
What is opsin needed for?
Transduction
What are the 3 classes of cone cells?
S-, M- and L-
How do the types of cones differ?
Differ in wavelength affinity to absorb light
How many functional classes of rod cells are there?
1 - express the same type of opsin (rhodopsin)
What are the first steps in processing an image?
- Lens focuses image
- Aperture to control light entering the iris
- Pixels register image (Photoreceptors)
- Filtering media
- Lens cover (eye lid)
- Cleaning mechanism (tears)
What is visual acuity?
Ability to solve spatial details
Where is acuity highest?
Fovea
What is the pathway of serial connections in the retina?
Photoreceptors -> Bipolar cells -> ganglion cells -> thalamus and the brain areas
How are horizontal cells involved?
Receive input from photoreceptors and project to bipolar cells
How are amacrine cells involved?
Receives input from bipolar cells and project to ganglion cells
What is the Geniculate-striate visual pathway needed for?
Conscious vision in humans
What is the V1 and what is it required for?
Primary visual cortex, conscious visual experiences
What are examples of an Extrageniculate pathway?
Retina - SC used for eye movement
How do retinal ganglion cells project to each layer of the LGN?
Retinotopically
What causes cortical blindness?
Damage to the V1
What are the 2 types of eye movement?
Saccades (jumps) and fixations (stops)
What is the definition of the field of view?
position and orientation of the eye ball. of the head and the body
What controls automatic movement of the eye?
Superior colliculus
What controls conscious control of the eye?
Frontal eye fields
What are the first stages of visual processing with inhibitory and excitatory synapses?
Edge detection, edge enhancements, filtering of spatial, wavelength, movement and directional information
What is convergence?
how sensory details, such as sight or touch, are combined and evaluated to form perceptions
What are filter mechanisms in the retina?
Neural circuits that combine excitatory and inhibitory synapses
What are the 2 types of centre-surround receptive field?
Bipolar and ganglion cells with ON-centre/ OFF-surround receptive field
Bipolar and ganglion cells with OFF- centre/ON-surround receptive field
