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Definition
| the center of vision, where vision is most acute and color vision is best. Cone photoreceptors are most prevalent here. |
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| The back of the eyeball, considered a part of the brain, where light hits the photoreceptive cells and visual information begins being processed. |
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| Where the axons of the retinal ganglion cells leave the retina and head back towards the optic chiasm in the brain, taking with them visual information. This nerve is the reasons humans have a blindspot, because no photoreceptors cells exist where the optic nerve enters the eye. |
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| Cells in the retina that receive input from modulatory neurons (which get input from photoreceptor cells) and transmit the information down the optic nerve to the brain. |
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Definition
| Cells that line the back of the retina and have parts that change shape when they are hit with photon, allowing them to detect light in a certain part of the visual field. Humans have two main types, rods and cones, and there are three different subtypes of cones. |
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Definition
| Photoreceptor cells that are located outside the fovea. They are responsible for low-light vision (highly sensitive to light) and useful for detecting movement, but at the cost of visual acuity. They do not differentiate between colors. |
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Definition
| Photoreceptor cells that are located primarily in the fovea. They are responsible for high acuity vision, but take more photons of light to activate (good for daytime vision). There are three types, each most responsive to different wavelengths of light (corresponding to red, green, and blue), which, when combined, allow for color vision. |
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Definition
| A visual processing stream that pools over fewer receptors. The cells involved (midget cells) have a sustained response and are involved in processing color, fine details, textures, and depth. |
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Definition
| A visual processing stream that pools over many receptors, whose cells (parasol cells) fire in bursts and are useful for detecting motion |
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Definition
| A visual processing stream that gets S-Cone input only, processing low acuity visual information, and innervating V1 and extrastriate cortex. |
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Definition
| Where the optic nerves cross in the brain, allowing information from the left visual field (from both eyes) and the right visual field (from both eyes) to be separated and directed to the appropriate contralateral hemisphere. |
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Term
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Definition
| A part of the brain involved in sensory information from sensory organs to processing areas of the cerebral cortex. |
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Term
| Lateral Geniculate Nucleus (LGN) |
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Definition
| A part of the halamus where the visual processing streams pass through on their way to the optic radiations and primary visual cortex. |
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Definition
| Nerve pathway along the visual processing stream from LGN to primary visual cortex. |
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Definition
| An area of impaired or lost vision in the visual field |
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Definition
| The first stage in the functioning of the senses, starting with information at the peripheral sensory receptors. |
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| The process of recognizing, organizing, and interpreting sensory information. |
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Definition
| A phenomenon where people who are perceptually blind demonstrate some response to visual stimuli (because only part of their visual system is impaired, other parts my still function) |
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Definition
| Made up of multiple visual areas, it is one of two main visual processing streams after primary visual cortex. This pathway is involved in the perception for action. |
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Definition
| Made up of multiple visual areas, it is one of two main visual processing streams after primary visual cortex. This pathway is involved in perception for recognition. |
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Definition
| Inability to recognize and identify objects or persons despite having knowledge of the characteristics of the objects or persons. |
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Definition
| A disorder characterized by the inability to name, copy, or recognize visually represented objects. Shape perception and figure-ground segregation is impaired, but basic visual functions (color discrimination, luminance discrimination, visual acuity) and object identification based on non-visual cues are preserved. |
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Term
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Definition
| A disorder in which visual object recognition is impaired (e.g. naming of visually presented objects, categorization, matching by function), but more or less preserved is elementary visual perception (e.g. matching and copying of visually presented forms and objects, drawing objects from memory, and non-visual object recognition. |
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Term
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Definition
| A disorder in which visual object recognition is impaired. (e.g. naming of a visually presented objects, categorization, matching by function), but more or less preserved is elementary visual perception. (e.g. matching and copying of visually presented forms and objects, drawing objects from memory, and non-visual object recognition) |
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Definition
| A bilateral visual processing area that is thought to be specialized for face processing (with some controversy -- some authors argue that it is specialized for detailed visuospatial processing, not necessarily just face processing). |
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Definition
| The inability to detect facial features that are inverted on an inverted fact (i.e. the features would be upside down, and very obvious, if they were turned right-side up) because we are so used to processing faces in the upright orientation. |
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Definition
| A disorder in which faces cannot be recognized, but other forms of object recognition are unimpaired. |
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Definition
| The delusional belief that an acquaintance has been replaced by an identical-looking impostor. It may be seen in schizophrenia, dementia, and brain trauma. |
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Definition
| The delusional belief that different people are in fact a single person who changes appearance or is in disguise, generally viewed with paranoia (that the "shape-shifting" person is out to get them). |
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