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Rod
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Rod Photoreceptor for dim light conditions. Achromatic, lower acuity and temporal resolution than cones, outnumber cones 20 to 1. Rod system is convergent (many rods target one bipolar cell). See also Cone.
RELATED TERMS--------------------------------------
Photoreceptor
A light sensitive neuron. Photoreceptors interact with light which produces changes in their electrical properties which are communicated to other neurons. They constitute the first stage in the physiological process which underlies vision. The human retina, like the retina of most vertebrates, contains two broad classes of photo-receptors, rods and cones.
Acuity
The highest spatial frequency rsolvable with a grating of unity contrast (i.e. the maximum possibly contrast).
Temporal
Having to do with the side of the head.
Rods
The rods are the visual cells of the retina that are important for night vision and peripheral vision. The rods are the first affected in rod-cone degenerations such as RP.
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Retinotectal pathway
Pathway from the retina to superior colliculi.
Retinotopic map
A preservation of the spatial relationships of the photoreceptors in the retina in a higher brain representation.
Rhodopsin
The visual pigment in rod cells. Contains opsin and retinal.
Right visual hemifield
The right half of the visual field, projects on the nasal hemiretina of the right eye and on the temporal hemiretina of the left eye.
Rivalry
When two different images are presented to the two eyes simulataneously, a mosaic-like percept can be obtained, in which different regions of the image correspond to left and right eye images.
Rod
Reniform
Shaped like a kidney.
Resilient
Having the ability to return to an original shape after having been compressed or deformed.
Rationalization
A defense mechanism, operating unconsciously, in which an individual attempts to justify or make consciously tolerable by plausible means, feelings or behavior that otherwise would be intolerable. Not to be confused with conscious evasion or dissimulation. See also projection.
Reaction formation
A defense mechanism, operating unconsciously, in which a person adopts affects, ideas, and behaviors that are the opposites of impulses harbored either consciously or unconsciously. For example, excessive moral zeal may be a reaction to strong but repressed asocial impulses.
Reality principle
In psychoanalytic theory, the concept that the pleasure principle, which represents the claims of instinctual wishes, is normally modified by the demands and requirements of the external world. In fact, the reality principle may still work on behalf of the pleasure principle but reflects compromises and allows for the postponement of gratification to a more appropriate time. The reality principle usually becomes more prominent in the course of development but may be weak in certain psychiatric illnesses and undergo strengthening during treatment. reality testing The ability to evaluate the external world objectively and to differentiate adequately between it and the internal world. Falsification of reality, as with massive denial or projection, indicates a severe disturbance of ego functioning and/or of the perceptual and memory processes upon which it is partly based.
RELATED TERMS--------------------------------------
Photoreceptor
A light sensitive neuron. Photoreceptors interact with light which produces changes in their electrical properties which are communicated to other neurons. They constitute the first stage in the physiological process which underlies vision. The human retina, like the retina of most vertebrates, contains two broad classes of photo-receptors, rods and cones.
Acuity
The highest spatial frequency rsolvable with a grating of unity contrast (i.e. the maximum possibly contrast).
Temporal
Having to do with the side of the head.
Rods
The rods are the visual cells of the retina that are important for night vision and peripheral vision. The rods are the first affected in rod-cone degenerations such as RP.
SIMILAR TERMS--------------------------------------
PREVIOUS AND NEXT TERMS--------------------------------------
Retinotectal pathway
Pathway from the retina to superior colliculi.
Retinotopic map
A preservation of the spatial relationships of the photoreceptors in the retina in a higher brain representation.
Rhodopsin
The visual pigment in rod cells. Contains opsin and retinal.
Right visual hemifield
The right half of the visual field, projects on the nasal hemiretina of the right eye and on the temporal hemiretina of the left eye.
Rivalry
When two different images are presented to the two eyes simulataneously, a mosaic-like percept can be obtained, in which different regions of the image correspond to left and right eye images.
Rod
Reniform
Shaped like a kidney.
Resilient
Having the ability to return to an original shape after having been compressed or deformed.
Rationalization
A defense mechanism, operating unconsciously, in which an individual attempts to justify or make consciously tolerable by plausible means, feelings or behavior that otherwise would be intolerable. Not to be confused with conscious evasion or dissimulation. See also projection.
Reaction formation
A defense mechanism, operating unconsciously, in which a person adopts affects, ideas, and behaviors that are the opposites of impulses harbored either consciously or unconsciously. For example, excessive moral zeal may be a reaction to strong but repressed asocial impulses.
Reality principle
In psychoanalytic theory, the concept that the pleasure principle, which represents the claims of instinctual wishes, is normally modified by the demands and requirements of the external world. In fact, the reality principle may still work on behalf of the pleasure principle but reflects compromises and allows for the postponement of gratification to a more appropriate time. The reality principle usually becomes more prominent in the course of development but may be weak in certain psychiatric illnesses and undergo strengthening during treatment. reality testing The ability to evaluate the external world objectively and to differentiate adequately between it and the internal world. Falsification of reality, as with massive denial or projection, indicates a severe disturbance of ego functioning and/or of the perceptual and memory processes upon which it is partly based.
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This dictionary contains 19186 terms.
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