~Chapter 3 - Lectures Flashcards
Horseshoe Crabs eye are positioned ___ on their head
Laterally
What is a Compound eye?
An eye where each facet of the compound eye, which is called an Ommatidium, functions as a separate, or independent photoreception unit
Who used Horseshoe Crabs to research eyes?
Hartline
Omaatidium are connected by ___
Axons referred to as the Lateral Plexus
What happens during Lateral Inhibition?
Stimuli lateral to the recorded neuron appear to inhibit the neuron’s response
What Illusions are often used in examples of Lateral Inhibtion?
Chevreul (staircase) Illusion and Mach Bands
In the Mach Bands illusion, both the light and dark bands are ___
Illusory, when measuring the shadows with a light measure, you will see that both the light and dark bands are illusory, your visual system is telling you something is there when it is not
What is Center-Surround Antagonism?
Center-surround antagonism refers to antagonistic interactions between center and surround regions of the receptive fields of photoreceptor cells in the retina
What can Lateral Inhibition not explain?
Lateral inhibition at the level of the photoreceptors cannot explain the perceptions of the Chevreul illusion and Hermann Grid
There is a cycle between ___ that are created and the ___ that they predict
Physiological models // perceptions
Lateral Inhibition predicts the ___ than what is perceived in ___
opposite effect // White’s illusion
What happens when you change the connectivity of neural circuits?
You change their properties and function
What is the visual system definition of a Receptive Field?
An area on the retina that when stimulated with some pattern of light can affect the firing of a neuron.
But also because of the optics of the eye, it can be thought of as an area out in your visual field in your space, that when stimulated, can affect the firing of a neuron.
What is the function of Receptive Fields?
Receptive fields analyze the images of objects in the world
What are Center-Surround Receptive Fields that have Center-Surround Antagonism?
Donut-shaped area that prefers one type of stimulus and the central area prefers another type of stimulus.
___ regions are excited by luminance increment
“On”
___ regions are excited by decrement
“Off”
What cells have Center-Surround Receptive Fields?
Retinal Ganglion cells, Bipolar cells, and photoreceptors
What happens when you shine a light on an “Off” region in a Center-Surround Receptive Fields?
The cell is going to be inhibited, and it’s going to not fire any spikes.
What happens when you shine a light on an “On” region in a Center-Surround Receptive Field?
There is a strong response in firing
You are shining a light onto an “On” region in a Center-Surround Receptive Field, you then turn the light off, what happens?
The cell stops responding/firing
You are shining a light into an “Off” region in a Center-Surround Receptive Field, you then turn the light off, what happens?
You’re going from brighter to darker and this counts as luminance decrement, that causes a burst in excitation of the cell
In Center-Surround Antagonism, the light and dark regions ___ each other
Oppose
You shine a light over both regions in a Center-Surround Receptive Field, what happens?
You get spontaneous activity where the cell is not excited or inhibited, it’s spontaneously firing.
Luminance Increment produces ___ in “On” regions and ___ in “Off” regions
Excitation // Inhibition
Luminance Decrement produces ___ in “On” regions and ___ in “Off” regions
Inhibition // Excitation
How does hyperpolarization in one cell create excitation in another?
Release from inhibition
If the neurotransmitter is being treated as inhibitory it will create a ___ which will create an ___ bipolar cell
Sign Inverting Synapse // on-center
Photoreceptors always release ___
Glutamate
Bipolar cells treat Glutamate as inhibitory to make an ___ response
on-center
Bipolar cells treat Glutamate as excitatory to make an ___ response
off-center
When you shine a light on a photoreceptor, ___ bipolar cells will become excited
on-center
If a neurotransmitter is being treated as excitatory it will create a ___ which will create an ___ bipolar cell
Sign Conserving Synapse // off-center
Photoreceptors release ___ glutamate when they are depolarized
More
Photoreceptors release ___ glutamate when they are hyperpolarized
Less
Photoreceptors are most simple at the ___
Synapse
On-Center Bipolar cells treat glutamate as ___
inhibitory
Off-Center Bipolar cells treat glutamate as ___
excitatory
How does Lateral Inhibition create Center-Surround Receptive Fields in the Retina?
By using Horizontal cells
Where does Lateral Inhibition occur?
On the Photoreceptors
What is the order of cells in the Visual Pathway?
Photoreceptors → Bipolar cells → Ganglion cells in the eye