Visual Flashcards
(24 cards)
Eye movement: vergence movements
Movement of both eyes to make sure the image being looked at is on the corresponding part of the retina
Description of light passage through the eye
Description of organs
- Cornea- protective clear covering over pupil/iris. Light bends
- Pupil- dark circle in the middle of the iris (colored portion, controls the amount of light). The pupil brings the picture into focus.
- Lens- clear, flexible structure that focuses the image (close or far) on the retina.
- Retina- layer of light sensitive cells on the back of the eye
- cones: bright light, color
- rods: more sensitive and more numerous
- Optic Nerve- receives signals from the retina and sends them to the brain
Eye Movements: saccades
Short and rapid movement while scanning a scene. Speed cannot be consciously controlled in between the stops
Eye movements: pursuit movements
Movements the eye makes while tracking an object’s movement
Rods
Dark/low illumination, sensitive to movement of the peripheral vision
More numerous than cones. Densest around the edge of the fovea
Sensitive to reflected brightness
Cones
Most dense of the part of the retina where images are most sharply focused by the cornea and lens
Sensitive to color and foveal vision
Foveal Vision
What you can read when focusing on one thing and not moving your gaze (cones)
Sequence of events on the retina
- Photoreceptor Cells: cones/rods
- Bipolar Cells
- Ganglion Cells
Optic Chiasm
Decussation occurs, the crossing over
Left visual field gets processed in the right side of the brain.
Right visual field gets processed in the left side of the brain.
The left visual field of the right eye is already on the right side.
The right visual field of the left eye is already on the left side, aka the correct side.
Retinotectal
Nerve fibers connecting the retina and the midbrain
Suprachiasmatic Nucleus
Gets neve signals directly from the retina. Color, contrast, shape, and movement.
Receptive field of a ganglion cell
Composed of the input of from all of the photoreceptors which synapse with it
Lateral Inhibition
Capacity of an excited neuron to reduce the activity of its neighbors.
It increases sharpness and contrast in visual response.
Balints Syndrome
Can’t report two things that overlap visual space but can report them if they are separate.
Simple Cells of the PVC
Responds primarily to oriented edges and gratings.
Complex Cell of the PVC
Does the same as the simple cell (responds to oriented edges and gratings) but its receptive field cannot be mapped into fixed zones.
It will respond to light in a huge receptive field, regardless of location.
Ventral Stream
Object recognition (what is it?) Temporal lobe pathway --> inferior temporal cortex
Dorsal Stream
Where/context/space (what is it?)
Parietal lobe pathway –> posterior parietal
Prosopagnosia
Loss of knowledge of faces, deficit in face recognition
- angular gyrus is the main suspect
Movement Agnosia
Inability to recognize the movement of an object, water falling out of a faucet is frozen
Inferior temporal
Ventral stream, representation of complex object features. Damage to this could lead to prosopagnosia
Posterior parietal
Dorsal stream, helps guiding movement of body parts. Damage to this could lead to not being able to get your hand to the item you want to touch.
Blindsight
Can detect things but cannot identify them.
This is because their eyes receive the information but don’t know what to do with it, they don’t process it correctly.
Synesthesia
Stimulation of one sensory pathway leads to automatic, involuntary experiences in a second sensory pathway.
Video of guy being able to see shapes made out of letters that would only be there if they were colored differently.
