Midterm 2: Chapter 3.4 Flashcards
Interconnected groups of neurons (within the retina)
Neural Circuits
Signals generated in the receptors travel to the ______________ _________.
Bipolar Cells
After bipolar cells, where do signals travel to?
Ganglion Cells
Why do ganglion cells have long axons?
to transmit signals out of the retina in the optic nerve.
What are two other types of neurons that connect neurons across the retina?
Horizontal cells and amacrine cells
Where does light come in?
From the bottom where the ganglion cells are.
Occurs when a number of neurons synapse onto a single neuron
Neural convergence
Order of cells in the retina?
- Rods and cone receptors
- Horizontal cells
- Bipolar cells
- Amacrine cells
- Ganglion cells
The small area that contains only cones
Fovea
True or false: Each ganglion cell receives signals from only one cone.
TRUE
What does greater convergence of rods compared to cones translate to?
- rods result in better sensitivity than the cones
- the conses result in better detail vision than the rods.
Which is better to use in the dark? rods or cones?
Rods
Why do rods have greater sensitivity compared to rods?
it takes less light to generate a response from an individual rod receptor than from an individual cone receptor. And rods have greater convergence
True or false: The rods have greater convergence than the cones.
TRUE
Why do cones have better visual acuity?
they have less convergence
Refers to the ability to see details
Acuity
When you move your eyes to look at different things in the way of looking for something, what are you doing?
Scanning with your cone-rich fovea
When you look at something directly, where does the image fall?
On the fovea
Where is your visual acuity highest?
Fovea
What does high convergence result in?
high sensitivity but poor acuity
What does low convergence result in?
low sensitivity but high acuity
The region of the retina that must receive illumination in order to obtain a response in any given fiber
Receptive field
arranged like concentric circles in a center-surround organization. The area “center” of the receptive field of the receptive field responds differently to light than the area in the “surrounding” of the receptive field.
center-surround receptive fields
What is this receptive field called?
- Presenting a spot of light to the center increases the firing (Excitatory area)
- stimulation of the surround causes a decrease in firing (Inhibitory area)
excitatory-center, inhibitory-surround receptive field
What is this receptive field called?
- responds with inhibition when the center is stimulated
- responds with excitation when the surround is stimulated
inhibitory center, excitatory-surround receptive field
- antagonistic interactions between the center and surrounding regions of the receptive fields of photoreceptor cells in the retina.
- come into play when the spot of light becomes large enough that it begins to cover the inhibitory area.
Center-surround antagonism
Inhibition that is transmitted across the retina
Lateral inhibition
Which cells are responsible for lateral inhibition?
Horizontal and amacrine cells
An increase in perceived contrast at borders between regions of the visual field
Edge enhancement
a brightness illusion that occurs when adjacent bands of different luminance are perceived as inhomogeneous
Chevreul illusion
Light and dark bands created at fuzzy borders; an optical illusion caused by an inherent edge enhancement by the retina, resulting in a darker edge of a dark object adjacent to a light object, and vice versa
Mach bands
True or false: Infants choose to look at objects with contours over ones that are homogeneous
TRUE
