6 Vision Flashcards
Sensory transduction
The process by which sensory stimuli are transduced into slow, graded receptor potentials.
Sensory receptor
Specialized neuron that detects a particular category of physical events.
Receptor potential
Slow, graded electrical potential produced by a receptor cell response to a physical stimulus.
Hue
dominant wavelength.
Brightness
Intensity
Saturation
Purity
vergence movement
Cooperative movement of the eyes, which ensures that the image of an object falls on identical portions of both retinas.
Saccadic movement
Rapid, jerky movements of the eyes using scanning a visual scene.
Pursued movement
Movement that the eyes make to maintain an image of a moving object on the phobia.
Accommodation
Changes in the thickness of the lens of the eye, accomplished by this ciliary muscles, that focus images of near or distant objects on the retina.
Retina
Neural tissue in photoreceptor cells located on the inner surface of the posterior portion of the eye.
Rod
One of the receptor cells of the retina, sensitive to light of low intensity.
Cone
Maximally sensitive to one of three different wavelengths of light and hence encodes color vision.
Photoreceptor
Transducers photic energy into electrical potentials.
Fovea
Region of the retina that mediates the most acute visions of birds and higher animals. Color-sensitive cones constitute the only type of photoreceptor found in the fovea.
Optic disc
Location of the exit point from the retina of the fibers of the ganglion cell deforming optical nerve, responsible for the blind spot.
Bipolar cell
Bipolar neuron located in the middle layer of the retina, conveying information from the photo receptors to the ganglion cells.
Ganglion cell
Neuron located in the retina that receives visual information from bipolar cells, its axons give rise to the optic nerve.
Horizontal cell
Neuron in the retina that interconnects adjacent photoreceptors and the outer processes of the bipolar cells.
amacrine cell
Neuron in the retina that interconnects adjacent ganglion cells and the inner processes of the bipolar cells.
Lamella
Layer of membrane containing photo pigment; found in rods and cones of the retina.
Photopigment
Protein dye bonded to retinal, a substance derived from vitamin A; responsible for transduction of visual information.
Opsin
Class of protein that, together with retinal, constitutes the photopigments.
Retinal
Chemical synthesized from vitamin A; joins with an option to form a photopigment.
Rhodopsin
Particular opsin found in rods.
Dorsal lateral geniculate nucleus (LGN)
Group of cell bodies within the lateral geniculate body of the thalamus; receives inputs from the retina and projects to the primary visual cortex.
Magnocellular layer
One of the inner two layers of neurons in the dorsolateral geniculate nucleus; transmits information necessary for the perception of form, movement, depth, and small differences and brightness to the primary visual cortex.
Parvocellular layer
One of the four the outer layers of neurons in the dorsal lateral geniculate nucleus; transmits information necessary for perception of color and find details to the primary visual cortex.
koniocellular sublayer
One of the settlers of neurons in the dorsolateral geniculate nucleus found ventral to each of the magnocellular and parvocellular layers; transmit information from short-wavelength (“blue”) cones to the primary visual cortex.
Calcarine fissure
Horizontal fissure on the inner surface of the posterior cerebral cortex; location of the primary visual cortex.
Striate cortex
Primary visual cortex
Optic chiasm
Cross-shaped connection between the optic nerves, located below the base of the brain, just anterior to the pituitary gland.
Receptive field
Portion of the visual field in which the presentation of visual stimuli will produce an alteration in the firing rate of a particular neuron.
Protanopia
Inherited form of defective color vision in which red and green hues are confused, red cones are filled with green cone opsin.
Deuteranopia
Inherited form of defective color vision which red and green hues are confused; green cones are filled with red cone opsin.
Tritanopia
Inherited form of defective color vision which use with short wavelengths are confused; blue cones are either lacking or faulty.
Negative afterimage
Image seen after portion of the retina is exposed to an intense visual stimulus; consist of colors complementary to those of the physical stimulus.
Complementary colors
Colors that make white or gray mixed together.
Simple cell
Orientation-sensitive neuron in the striate cortex was receptive field is organized in opponent fashion.
Complex cell
Neuron in the visual cortex that response to the presence of a line segment with a particular orientation located within its receptive field, especially when the line moves perpendicularly to its orientation.
Hypercomplex cell
Neuron in the visual cortex that responds to the presence of a line segment with a particular orientation that ends at a particular point within the cell’s receptive field.
Sine-wave grating
Series of straight parallel bands very continuously in brightness according to a sine-wave function, along the line perpendicular to their lengths.
Spatial frequency
The relative with of the bands in a sine wave grating, measured in cycles per degree of visual angle.
Retinal disparity
The fact that points on objects located at different distances from the observer will fall on slightly different locations on the two retinas; provides the basis for stereopsis.
Cytochrome oxidase (CO) blob
Central region of a module of the primary visual cortex, revealed by a stain for cytochrome oxidase; contains wavelengths-sensitive neurons; part of the parvocellular system.
Ocular dominance
Extent to which a particular neuron receives more input from one eye than the other.
Extrastiate cortex
Region of visual association cortex; receives fibers from the striate cortex and from the superior colliculi and projects to the inferior temporal cortex.
Dorsal stream
System of interconnected regions of visual cortex involved in the perception of spatial location, beginning with the striate cortex and ending with the posterior parietal cortex.
Ventral stream
System of interconnected regions of visual cortex involved in the perception of form, beginning with the striate cortex and ending with the inferior temporal cortex.
Inferior temporal cortex
Highest level of the ventral stream of the visual association cortex; involved in perception of objects, including people’s bodies and faces.
Posterior parietal cortex
Highest level of the dorsal stream of the visual association cortex; involved in perception of movement and spatial location.
Color constancy
The relatively constant appearance of the colors of objects viewed under varying lighting conditions.
Cerebral achromatopsia
Inability to discriminate among different hues; caused by damage to area V8 of the visual association cortex.
Visual agnosia
Deficits in visual perception in the absence of blindness; caused by brain damage.
Lateral occipital complex (LOC)
Region of the extrastriate cortex, involved in perception of objects other than people’s bodies and faces.
Prosopagnosia
Failure to recognize particular people by the side of their faces.
Fusiform face area (FSA)
Region of the visual association cortex located in the inferior temporal; involved in perception of faces and other complex objects that require expertise to recognize.
Extrastriate body area (EBA)
Region of the visual association cortex located in the lateral occipitotemporal cortex; involved in perception of the human body and body parts other than faces.
Parahippocampal place area (PPA)
Region of limbic cortex on the medial temporal lobe; involved in perception of particular places (scenes).
Optic flow
Complex motion of points in the visual field caused by relative movement between the observer and environment; provides information about the relative distance of objects from the observer and the relative direction of movement.
Akinetopsia
Inability to perceive movement, caused by damage to the area V5 (also called MST) of the visual association cortex.
Intraparietal sulcus (IPS)
The end of the dorsal stream of the visual association cortex; involved in perception of location, visual attention, and control of eye and hand movements.
