Vision Flashcards
What wavelengths of electromagnetic radiationcan we see?
380-760 nanometres
Colour and brightness are?
Colour = wavelength Brightness = amplitude
Sclera
The tough white tissue covering the eye
Cornea
The small round window in the sclera
Aqueous Humour
Fluid that fills the front of the eye until reaching the pupil
Pupil and Iris
Pupil is the aperture of the eye. The iris is the ring of muscles that controls its wideness (controlled by autonomic nervous system)
Lens is controlled by?
Ciliary muscles
Vitreous Humour
The fluid inside the eye
Retina
The back of the eye, contains photoreceptors
Choroid
Black lining inside the eye
Photoreceptors
Located in the back of the retina. Consist of rods and cones.
Fovea
Spot at back of retina in which the majority of cones are located
Fovea
Spot at back of retina in which the majority of cones are located
Photopigments
Chemical in rods and cones the absorb light and transduce it into neural information
‘On’ bipolars and ‘off’ bipolars
On = become more active (depolarise) to visual input off = become less active (hyperpolarise) to visual input
where do Ganglion cells receive info from and project info to?
receive information from Bipolar cells, project to Optic Nerve
Horizontal cells
Interconnect photoreceptors (rods and cones)
Amacrine cells
Link between bipolar and ganglion cells
Pathway of light to optic nerve:
Light - Rods/cones - Bipolar cells - Ganglion cells - Optic Nerve
Optic Chiasm
Part where two optic nerves converge and visual information crosses to the other side of the brain (not all)
Optic Tract
although there are no synapses involved, the pathway coming out of the Optic Chiasm is called the Optic Tract
Lateral Geniculate Nucleus
Gets information from optic tract and projects it to the Primary Visual Cortex, which is located in the Occipital lobe
Lateral Geniculate Nucleus
Gets information from optic tract and projects it to the Primary Visual Cortex, which is located in the Occipital lobe
Parvocellular cells
in the geniculate nucleus. constitute the top 4 layers. Receive information mostly from the fovea
Magnocellular cells
In the geniculate nucleus. Constitute bottom 2 layers. Receive information from periphery of retina.
Optic Radiations
The pathway from the lateral geniculate nucleus to the primary visual cortex
Primary Visual Cortex
It is here the information from both eyes is combined for the first time
Receptive field
The area in which a response is generated within photoreceptors
Simple cells
Detect straight lines, edges. Stimulus has to be in correct orientation and place in the receptive field
Complex cells
Detect stimulus anywhere in the receptive field, provided it is in the correct orientation
Hypercomplex cells
Detect stimulus of correct orientation and length (also called end-stopped)
Orientation columns
moving vertically in visual cortex, simple, complex and hypercomplex cells all triggered by same orientation.
Three different types of cone
Blue, Green and Red
Three different types of cone
Blue, Green and Red
Trichromatic Theory of colour vision
Three colour receptors; blue, green and red which, when combined, could detect any colour
Opponent theory
Three colour receptors which detect opposites: Blue-yellow, red-green and black-white
Cells in cytochrome blobs are sensitive to?
Colour (they are located in the visual cortex)
450nm looks like?
Blue
550nm looks like?
green
600nm looks like?
Yellow
700nm looks like?
Red
Orientation detection is coded by:
Simple cortical cells
Luminance contrast (edges) are first coded by
Ganglion cells
scotopic vision
vision in the dark
photopic vision
Vision under well-lit conditions
Dorsal pathway
through the parietal lobes - spatial location of objects
Ventral Pathway
through the temporal lobes - Visual recognition of objects
Presbyopia
When the flexibility of the lens diminishes (what happens to old people)
Myopia
When the lens fails to flatten (short-sightedness)
Myopia
When the lens fails to flatten (short-sightedness)
Parvocellular and Magnocellular cells are found?
In the Lateral Geniculate Nucleus - Parvocellular = top 4 layers, Magnocellular = bottom 2 layers
Cortical modules contain
Orientation columns, ocular dominance columns and cytochrome blobs
P Cells (Parvocellular)
Colour, contrast
M Cells (Magnocellular)
Movement
