3: Neural Processing & Perception Flashcards
Inhibition that is transmitted across the retina is called what?
Lateral inhibition.
Why was the Limulus chosen to demonstrate lateral inhibition?
Structure of its eye makes it possible to stimulate individual receptors.
The Limulus eye is made up of hundreds of tiny structures called what? Describe them.
Ommatidia. Each ommatidium has small lens on eye’s surface that is located directly over a single receptor.
Perceived light and dark bands at the borders, which are not present in the actual physical stimuli, constitute what? It is also called the staircase illusion - why?
Chevreul illusion.
Because of steplike pattern of intensities on display.
How does hyperpolarization in one cell create excitation in another?
Release from inhibition.
What comprises a sign inverting synapse? Sign conserving?
Invaginating bipolar cell. Flat bipolar cell.
Photoreceptors always release _____. How do on-centre and off-centre bipolar cells treat it?
Glutamate.
On-center: treat as inhibitory
Off-centre: treat as excitatory
Horizontal cells transmit _____ directly to _____.
Lateral inhibition. Neighbouring photoreceptors.
What is the visual pathway?
Light energy → eye → optic nerve → optic chiasm → lateral geniculate nucleus (thalamus) → superior colliculus → visual receiving area (striate cortex).
What is the role of the lateral geniculate nucleus?
Control information flow to cortex. Greater flow from cortex than from retina.
Bottom-up: from retina
Top-down: from cortex
Describe simple cells. What are their on and off regions?
Respond to bars of light at a particular orientation. Moving or stationary stimuli. Sometimes direction selective.
Separate on and off regions.
Describe complex cells. What are their on and off regions?
Respond to bars of light at a particular orientation. Moving or stationary stimuli. Sometimes direction selective.
No separate on and off regions.
Describe end-stopped cells.
Respond to moving bars of light of a particular orientation and particular length, or moving “corners.”
Describe the four feature detectors.
Center-surround (retina or LGN): detect spot of certain size.
Simple cells: detect line of certain orientation.
Complex cells: detect line of certain orientation.
Hyper-complex cells: detect line of certain length and orientation.
Encoded features can become _____ as we move _____ the visual pathway.
More complex. Further down.
