20: Vision 3 Flashcards
Describe Ganglion Cell Receptive Fields
Are roughly circular
Are divided into two parts:
-A circular central zone (hence they are called the centre-surround receptive fields)
-An anulus around the centre, the surround
Describe the layers of the Ganglion cell receptive fields
- Array of photoreceptors
- Interneurons
- Ganglion cells
- Patterned light stimulus
Describe what occurs when there is a low convergence of ganglion cells
Small receptive fields, high acuity
Cones, fovea
Describe what occurs when there is a high convergence of ganglion cells
Large receptive fields, low acuity
Rods & cones, periphery
Where would there be high visual acuity
High acuity in fovea (small receptive fields)
Lower acuity away from fovea (large receptive fields)
Where do axons leave the retina?
Optic nerve.
There are no photoreceptors on the optic nerve (blind spot)
Where do axons from ganglion cells in nasal retinal cross?
At the optic chiasm to project contralaterally
Where do axons from gnglion cells in the temporal retina project
The do not cross and project ipsilaterally
Ganglion cells axons project to which four main subcortical visual areas?
- Superior colliculus
- Lateral Geniculate Nucleus
- Pretectum
- Suprechiasmatic nucleus
What is the superior colliculus involved in?
Concerned with eye movements and orientation to visual stimuli
What is the lateral geniculate nucleus involved in?
Concerned with the sensation of vision
What is the pretectum involved in?
Control of pupils
What is the suprachiasmatic nucleus involved in? (SCN)
Control of diurnal rhythms
After processing by the visual cortex, information can be sent to which lobes?
- Temporal lobe
- Parietal lobe
What is the role of the temporal lobe in regards to vision?
For identification of objects in visual space (the “what”)
