vision Flashcards
The transformation of sensory information into neural signals.
Transduction
The process of obtaining information about the environment and transmitting it to the brain for processing
Sensation
The process of interpreting sensory signals sent to the brain.
Pereption
A narrow focus of consciousness.
Attention
The combining of simpler meanings to construct more complex meanings
Bottom-up processing
The use of knowledge and expectation to interpret meanings
Top-down processing
-the energy that we can see
-it is one one of the forms of electromagenetic radiation produced by the sun
Visible light
Radiation emitted in the form of energy waves.
Electromagnetic radiation
The distance between successive peaks of a wave; determines color in visible light
Wavelength
Individual, indivisible, very small particles that form waves of electromagnetic energy.
Photons
A unit of measurement equaling 1 0-* m used to measure light wave frequency.
Nanometers
light that is visible to humans occupies a small part of the electromagnetic spectrum (appears white in teh human eye)
The range of electromagnetic energy visible to humans falls between 400 and 700 nanometers (nm).
The Electromagnetic Spectrum
The ability to retain something rather than reflect or transmit it to another location.
Absorption
The bending back of light toward its source
Reflection
The deflection, or changing of direction, of light at a boundary such as that between air and wate
Refraction
- a rapid closing of the eyelids, protects the eye from incoming objects and moistens and cleans the front of the eye
blink/blinking
- produced in the lacrimal gland at the outer corner of each eye. The fluid not only is composed primarily of water and salt but also contains proteins, glucose, and substances that kill bacteria.
Tears
- flush away dust and debris and moisten the eye so that the eyelids don’t scratch the surface during blinks.
Basal tears
- share a similar composition to basal tears but are released in large quantities in response to chemicals, bright lights, or debris in the eye.
Reflexive tears
- contain more hormones than basal or reflex tears, including leu-enkephalin, which acts as a natural painkiller.
Emotional tears
is roughly a sphere with a diameter of about 24 mm, just under one inch, and individual variations are very small, no more than 1 or 2 mm.
eye
-The white outer covering of the eye.
-helps the fluid-filled eyeball maintain its shape
Sclera
-The transparent outer layer of the eye
- it begins the process of bending or refracting light to form an image in the back of the eye.
Cornea
The area of the eye located directly behind the cornea, containing aqueous humor.
Anterior chamber
The fluid located in the anterior chamber that nourishes the cornea and lens.
Aqueous humor
The opening in the front of the eye controlled by the iris.
Pupil
The circular muscle in the front of the eye that controls the opening of the pupil
Iris (Greek word for “rainbow)
The clear structure behind the pupil and iris that focuses light on the retina.
Lens
The ability of the lens to change shape to adjust to the distance of the visual stimulus.
accommodation.
The large inner cavity of the eyeball
Vitreous chamber
The jellylike substance in the vitreous chamber.
Vitreous humor
The elaborate network of photoreceptors and interneurons at the back of the eye that is responsible for sensing light.
Retina
Specialized sensory cell in the retina that responds to light.
Photoreceptors
The area in the retina where blood vessels and the optic nerve exit the eyes
Optic disk
A 6 mm round area in the retina that is not covered by blood vessels and that is specialized for detailed and central vision
Macula
The ability to perceive visual stimuli focused on the macula of the retina.
Central vision
The ability to perceive visual stimuli that are off to the side while looking straight ahead.
Peripheral vision
A small pit in the macula specialized for detailed vision.
Fovea
The pigmented layer of cells supporting the photoreceptors of the retina.
Epithelium
The layer of retinal interneurons farthest from the photoreceptors, which contains ganglion cells and gives rise to the optic nerve.
Ganglion cell layer
Retinal cell in the ganglion cell layer whose axon leaves the eye as part of the optic nerve.
Ganglion cell
The location in the retina containing axons and dendrites that connect the ganglion, bipolar, and amacrine cells.
Inner plexiform layer
A retinal interneuron in the inner nuclear layer that integrates signals across adjacent segments of the retina.
Amacrine cell
A cell in the inner nuclear layer of the retina that forms part of the straight pathway between the photoreceptors and the ganglion cells.
Bipolar cell
The layer of retinal interneurons containing
amacrine, bipolar, and horizontal cells.
Inner nuclear layer
The retinal layer containing axons and dendrites forming connections between bipolar cells, horizontal cells, and the photoreceptors.
Outer plexiform layer
A retinal interneuron located in the inner nuclear layer that integrates signals from across the surface of the retina.
Horizontal cell
A pigment contained in the photoreceptors of the eye that absorbs light.
Photopigment
The two types of photoreceptors,
rods and cones
A photoreceptor that responds to low levels of light but not to color.
Rod
A photoreceptor that operates in bright conditions and responds differentially to color.
Cone
The ability to perceive visual stimuli under bright light conditions due to the activity of cones.
Photopic vision
A protein found in photopigments.
Rhodopsin
A chemical contained in rhodopsin that interacts with absorbed light. (Vitamin A)
Retinal
The form taken by retinal while it is bound to opsin in the absence oflight.
11-cis
The form taken by retinal after light is absorbed by the rod outer segment.
All-trans
The steady depolarization maintained by photoreceptors when no light is present.
Dark current
A second messenger within photoreceptors that is responsible for maintaining the dark current by opening sodium channels
Cyclic guanosine monophosphate (cGMP)
The _________are located in the inner nuclear layer.
They receive input from the photoreceptors and provide output to another type of cell in the inner nuclear layer, the bipolar cell.
HORIZONTAL CELLS
________, also located in the inner nuclear layer, receive input from photoreceptors and from horizontal cells. In turn, ________communicate with the amacrine cells in the inner nuclear layer and with ganglion cells.
bipolar cells
two major types of bipolar cells:
diffuse and midget.
cells are more common in the periphery of the retina, where a single _____ might receive input from as many as 50 rods.
Diffuse bipolar
cell located in the fovea might receive input from a single cone. ____________, influenced by a single cone, can provide information about light falling in a tiny part of the retina. This in turn contributes to the fine detail provided by photopic vision.
Midget bipolar
A location on the retina at which light affects the activity of a particular visual interneuron.
Receptive field
A characteristic of visual interneuron receptive fields, in which light illuminating the center has the opposite effect on the cell’s activity as light in the surround.
Antagonistic center-surround organization
The ability of an active neuron to inhibit the activity of adjacent neurons.
Lateral inhibition
_______, also located in the inner nuclear layer, form connections with bipolar cells, ganglion cells, and other amacrine cells.
Amacrine cells
_________ receive input from bipolar and amacrine cells. The axons of ganglion cells leave the eye to form the optic nerve, which travels to higher levels of the brain.
Ganglion cells
THE THREE TYPES OF GANGLION CELLS
P CELL
M CELL
K CELL
Small ganglion cell that responds to high contrast and color.
P cell -
- Large ganglion cell that responds to all wavelengths regardless of color, subtle differences in contrast, and stimuli that come and go rapidly.
M cell
A ganglion cell that does not fit the criteria for P or M cells exactly and responds to blue and yellow light.
K cell -
