vision Flashcards
Why is vision important for humans?
Make decisions and sense others - people, food, danger etc.
What is the role of light in vision?
Light (electromagnetic energy) enters the eyes and acts on photoreceptors in the retina, triggering neural impulses
How do different pathways in the brain process vision?
Separate pathways to the midbrain and cerebral cortex mediate motion, shape, color, and others
How does light enter the eye?
Light enters through the pupil, is focused by the cornea and lens, and reaches the retina at the back of the eye.
What is the function of the iris?
The iris adjusts pupil size in response to light levels.
What are the two types of photoreceptors in the retina?
Rods (low light) and cones (different wavelengths of light for color vision).
How do photoreceptors work?
Light triggers electrical signals that pass through retinal cells, activating ganglion cells whose axons form the optic nerve.
What is phototransduction?
The process of converting light into electrical signals in the rods and cones.
How do cones contribute to color vision?
There are three types of cones sensitive to different wavelengths of light, essential for color perception.
What is the optic chiasm?
The structure where optic nerve fibers partially cross, allowing each hemisphere of the brain to process visual input from both eyes.
What is binocularity?
The ability of visual cortex neurons to respond to images from both eyes, creating a unified visual perception.
How is visual space represented in the brain?
The left visual field is processed in the right hemisphere and vice versa.
What are the primary visual areas in the cortex?
Areas V1, V2, and others process different aspects like shape, color, and motion.
What is a receptive field?
The region of the retina over which a neuron responds to a specific visual stimulus.
What did Hubel and Wiesel discover?
Neurons in the visual cortex are arranged in columns, each responding to specific orientations of edges or lines.
What is visual cortex plasticity?
The ability of the visual cortex to adapt based on experience and visual input.
What is blindsight?
The ability to respond to visual stimuli without conscious awareness, seen in individuals with damage to V1.
How does functional blindsight affect everyday life?
People can perform actions like driving while focusing on a conversation, demonstrating unconscious visual processing.
How does the brain make visual decisions?
Sensory evidence is analyzed, compared with past knowledge, and used to make judgments.
How do neurons contribute to motion perception?
In area V5 (MT), neurons detect movement direction and adjust their activity based on the strength of the motion signal.
What experiment demonstrates neural motion detection?
A task where an observer identifies the direction of moving dots, with neurons in V5 reflecting the motion strength.
How do illusions reveal visual processing?
Illusions like the Necker cube and the café wall illusion show how the brain interprets ambiguous visual information.
How do neurons in V4 contribute to color perception?
Unlike neurons in V1 that respond to wavelengths, V4 neurons process colors based on surrounding context.
What is the Mondrian experiment?
A study showing that colors are perceived differently based on their surrounding hues, demonstrating contextual color processing.
