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ablation
this is usually done in experiments on animals, to determine the function of a particular area. Also called lesioning. TERM 2
brain imaging
DEFINITION 2 Procedures that make it possible to visualize areas of the human brain that are activated by different types of stimuli, tasks, or behaviors. The two most common techniques used in perception research are positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) TERM 3
complex cells
DEFINITION 3 A neuron in the visual cortex that responds best to moving bars with a particular orientation. TERM 4
contralateral eye
DEFINITION 4 The eye on the opposite side of the head from a particular structure. TERM 5
contrast threshold
DEFINITION 5 The intensity difference that can just barely be seen between two areas. This is often measured using gratings with alternating light and dark bars.
dissociation
A situation that occurs as a result of brain damage in which one function is present and another is absent. See also Double dissociation; Single dissociation. TERM 7
dorsal pathway
DEFINITION 7 Pathway that conducts signals from the striatev cortex to the parietal lobe. This is also called the where, the how, or the action pathway to indicate its function TERM 8
double dissociation
DEFINITION 8 In brain damage, when function A is present and function B is absent in one person, and function A is absent and function B is present in another. Presence of a double dissociation means that the two functions involve different mechanisms and operate independently of one another. TERM 9
end-stopped cells
DEFINITION 9 A cortical neuron that responds best to lines of a specific length that are moving in a particular direction. TERM 10
experience-dependent plasticity
DEFINITION 10 A process by which neurons adapt to the specific environment within which a person or animal lives. This is achieved when neurons change their response properties so they become tuned to respond best to stimuli that have been repeatedly experienced in the environment. See also Neural plasticity; Selective rearing.
hypercolumn
In the striate cortex, unit proposed by Hubel and Wiesel that combines location, orientation, and ocular dominance columns that serve a specific area on the retina. TERM 17
ipsilateral eye
DEFINITION 17 The eye on the same side of the head as the structure to which the eye sends inputs. TERM 18
landmark discrimination problem
DEFINITION 18 The behavioral task used in Ungerleider and Mishkins experiment in which they provided evidence for the dorsal, or where, visual processing stream. Monkeys were required to respond to a previously indicated location. TERM 19
lateral geniculate nucleus
DEFINITION 19 The nucleus in the thalamus that receives inputs from the optic nerve and, in turn, sends fibers to the cortical receiving area for vision. TERM 20
location column
DEFINITION 20 A column in the visual cortex that contains neurons with the same receptive field locations on the retina.
module
A structure that processes information about a specific behavior or perceptual quality. Often identified as a structure that contains a large proportion of neurons that respond selectively to a particular quality. TERM 22
neural plasticity
DEFINITION 22 The capacity of the nervous system to change in response to experience. Examples are how early visual experience can change the orientation selectivity of neurons in the visual cortex and how tactile experience can change the sizes of areas in the cortex that represent different parts of the body. TERM 23
neuropsychology
DEFINITION 23 the study of the behavioral effects of brain damage in humans. TERM 24
object discrimination problem
DEFINITION 24 The behavioral task used in Ungerleider and Mishkins experiment in which they provided evidence for the ventral, or what, visual processing stream. Monkeys were required to respond to an object with a particular shape. TERM 25
ocular dominance
DEFINITION 25 The degree to which a neuron is influenced by stimulation of each eye. A neuron has a large amount of ocular dominance if it responds only to stimulation of one eye. There is no ocular dominance if the neuron responds equally to stimulation of both eyes.
primary visual receiving area
The occipital cortex, where visual signals that originate in the eye first reach the cortex. TERM 32
prosopagnosia
DEFINITION 32 A form of visual agnosia in which the person cant recognize faces. TERM 33
retinotopic map
DEFINITION 33 A map on a structure in the visual system, such as the lateral geniculate nucleus or the cortex, that indicates locations on the structure that correspond to locations on the retina. In retinotopic maps, locations adjacent to each other on the retina are usually represented by locations that are adjacent to each other on the structure. TERM 34
rod and frame
illusion
DEFINITION 34 An illusion in which the perception of the orientation of a rod is affected by the orientation of a surrounding frame. TERM 35
selective adaptation
DEFINITION 35 A procedure in which a person or animal is selectively exposed to one stimulus, and then the effect of this exposure is assessed by testing with a wide range of stimuli. Exposing a person to vertical bars and then testing a persons sensitivity to bars of all orientations is an example of selective adaptation to orientation.
selective rearing
A procedure in which animals are reared in special environments. An example of selective rearing is the experiment in which kittens were reared in an environment of vertical stripes to determine the effect on orientation selectivity of cortical neurons. TERM 37
simple cortical cell
DEFINITION 37 A neuron in the visual cortex that responds best to bars of a particular orientation. TERM 38
single dissociation
DEFINITION 38 When, as a result of brain damage, one function is present and another is absent. Existence of a single dissociation indicates that the two functions involve different mechanisms but may not be totally independent of one another. TERM 39
striate cortex
DEFINITION 39 the visual receiving area of the cortex, located in the occipital lobe. TERM 40
subtraction technique
DEFINITION 40 A technique used to analyze the results of brain imaging experiments, in which brain activity elicited by a control condition is subtracted from the activity elicited by an experimental condition to determine the activity that can be attributed to the experimental condition alone.
