Behavioral Neuroscience: Exam 2 Flashcards
Two Types of Research Needed to Study Vision
- Research probing the components of the visual system
2. Research assessing what we see
Light can be thought of as…
- Particles of energy (photons)
- Waves of electromagnetic radiation
*Humans see light between 380-760 nanometers
Pupil
Light enters the eye through the pupil, whose size changes in response to changes in illumination.
Sensitivity
The ability to see when light is dim.
Acuity
The ability to see details.
Lens
Focuses light on the retina.
-Ciliary muscles alter the shape of the lens as needed
Accommodation
The process of adjusting the lends to bring images into focus.
Iris
Colored part of the eye. A specialized muscle flexes and relaxes to either open or close down the pupil.
Cornea
Sensitive membrane that holds fluid inside of the eye.
Sclera
Tough protective outer membrane of the eye.
Ocular Muscles
When these muscles move they roll the eye around the head and they attach to the tough outer layer of the eyeball.
Retina
Where transduction occurs. Transducers physical energy into electrochemical energy.
- The retina is in a sense “inside-out”
- Light passes through several layers before reaching its receptors
Fovea
Place of highest acuity on the retina - the place where you get the most detail.
Convergence
Eyes must turn slightly inward when objects are close.
Binocular Disparity
Difference between the images on the two retinas.
Vertical Pathway
Pathway of light through the layers of the retina - it flows both directions, photons flow in and action potentials flow out.
It has 3 primary layers:
- Receptors
- Bipolar Cells
- Retinal Ganglion Cells.
Blind Spot (Optic Disk)
No receptors where information exits the eye - the visual system uses information from cells around the blind spot for “completion”, filing in the blind spot.
Cones
- Photoscopic (daytime) vision
- High acuity color information in good lighting
- Only cones are found at the fovea
Rods
- Scotopic (nighttime vision)
- High sensitivity, allowing for low acuity vision in dim light, but lacks detail and color information
- More convergence than the cone system, increasing sensitivity while decreasing acuity
Spectral Sensitivity Curve
Shows the relationship between wavelength and brightness
Transduction
Conversion of one form of energy to another
Visual Transduction
Conversion of light to neural signals by visual receptors (photons to action potentials). Pigments absorb light.
Absorption Spectrum
Describes spectral sensitivity.
Retinotopic Organization
- Information received at adjacent portions of the retina remains adjacent in the striate cortex.
- More cortex is devoted to areas of high acuity - like the disproportionate representation of sensitive body parts in the somatosensory cortex.
- About 25% of primary visual cortex is dedicated to input from the fovea
Magnocellular Layers
- Big cell bodies, bottom two layers of the lateral geniculate nucleus
- Particularly responsive to movement
- Input primarily from rods
Parvocellular Layers
- Small cell bodies, top four layers of the lateral geniculate nucleus
- Color, detail, and still or slow objects
- Input primarily from cones
Mach Bands
Nonexistent stripes the visual system creates for contrast enhancement. Makes edges easier to see.
Receptive Field
The segment of the visual field for which an individual receptor is responsible.
Component Theory
(Trichoromatic Theory)
- 3 types of receptors, each with a different spectral sensitivity