Chapter 3 Flashcards
The smallest spatial detail that can be resolved at 100% contrast.
acuity
A reduction in response caused by prior or continuing stimulation.
adaptation
A developmental disorder characterized by reduced spatial vision in an otherwise healthy eye, even with proper correction for refractive error. Also known as lazy eye.
amblyopia
A condition in which the two eyes have different refractive errors (e.g., one eye is farsighted and the other not).
anisometropia
A vertical arrangement of neurons, which tend to have similar receptive fields and similar orientation preferences.
column
A cortical neuron whose receptive field does not have clearly defined excitatory and inhibitory regions.
complex cell
Referring to the opposite side of the body (or brain).
contralateral
A function describing how the sensitivity to contrast (defined as the reciprocal of the contrast threshold) depends on the spatial frequency (size) of the stimulus.
contrast sensitivity function (CSF)
The smallest amount of contrast required to detect a pattern.
contrast threshold
The difference in luminance between an object and the background, or between lighter and darker parts of the same object.
contrast
The amount of cortical area (usually specified in millimeters) devoted to a specific region (e.g., 1 degree) in the visual field.
cortical magnification
A phase in the life span during which abnormal early experience can alter normal neuronal development. Proposed for the development of binocular vision and development of a first human language.
critical period
For a grating, a pair consisting of one dark bar and one bright bar.
cycle
The number of pairs of dark and bright bars (cycles of a grating) per degree of visual angle.
cycles per degree
The process by which a cell in the cortex first increases its firing rate as the bar length increases to fill up its receptive field, and then decreases its firing rate as the bar is lengthened further.
end stopping
An acoustic, electrical, electronic, or optic device, instrument, computer program, or neuron that allows the passage of some range of parameters (e.g., orientations, frequencies) and blocks the passage of others.
filter
A 1-millimeter block of striate cortex containing two sets of columns, each covering every possible orientation (0–180 degrees), with one set preferring input from the left eye and one set preferring input from the right eye.
hypercolumn
Referring to the same side of the body (or brain).
ipsilateral
A neuron located between the magnocellular and parvocellular layers of the lateral geniculate nucleus. (From the Greek for “dust” referring to the appearance of the cells.)
koniocellular cell
A structure in the thalamus, part of the midbrain, that receives input from the retinal ganglion cells and has input and output connections to the visual cortex.
lateral geniculate nucleus (LGN)
Either of the bottom two neuron-containing layers of the lateral geniculate nucleus, the cells of which are physically larger than those in the top four layers.
magnocellular layer
The property of the receptive fields of striate cortex neurons by which they demonstrate a preference, responding somewhat more rapidly when a stimulus is presented in one eye than when it is presented in the other.
ocular dominance
The tendency of neurons in striate cortex to respond optimally to certain orientations and less to others.
orientation tuning
Any of the top four neuron-containing layers of the lateral geniculate nucleus, the cells of which are physically smaller than those in the bottom two layers.
parvocellular layer
The relative position of a grating.
phase
The area of the cerebral cortex of the brain that receives direct inputs from the lateral geniculate nucleus, as well as feedback from other brain areas.
primary visual cortex (V1), area 17, or striate cortex
A cortical neuron whose receptive field has clearly defined excitatory and inhibitory regions.
simple cell
A grating with a sinusoidal luminance profile as shown in Figure 3.4b.
sine wave grating
The number of cycles of a grating (e.g., dark and bright bars) per unit of visual angle (usually specified in cycles per degree).
spatial frequency
A pattern analyzer, implemented by an ensemble of cortical neurons, in which each set of neurons is tuned to a limited range of spatial frequencies.
spatial-frequency channel
A misalignment of the two eyes such that a single object in space is imaged on the fovea of one eye and on a nonfoveal area of the other (turned) eye.
strabismus
The perceptual illusion of tilt, produced by adaptation to a pattern of a given orientation.
tilt afteraffect
The orderly mapping of the world in the lateral geniculate nucleus and the visual cortex.
topographical mapping
The angle subtended by an object at the retina.
visual angle
The deleterious effect of clutter on peripheral object recognition.
visual crowding
