How do we sense, perceive, and see the world? Flashcards
retinohypothalamic tract
Neural route formed by axons of photosensitive retinal ganglion cells from the retina to the suprachiasmatic nucleus; allows light to entrain the rhythmic activity of the SCN.
fovea
Region at the center of the retina that is specialized for high acuity; its receptive fields are at the center of the eye’s visual field.
photoreceptor
Specialized type of retinal cell that transduces light into neural activity
opponent process
Explanation of color vision that emphasizes the importance of the apparently opposing pairs of colors: red versus green and blue versus yellow.
auditory flow
Change in sound heard as a person moves past a sound source or as a sound source moves past a person.
blind spot
Region of the retina where axons forming the optic nerve leave the eye and where blood vessels enter and leave; has no photoreceptors and is thus ‘blind.’
magnocellular (M) cell
Large-celled visual-system neuron that is sensitive to moving stimuli.
extrastriate (secondary visual) cortex
Visual cortical areas outside the striate cortex.
color constancy
Phenomenon whereby the perceived color of an object tends to remain constant relative to other colors, regardless of changes in illumination.
primary visual cortex (V1)
Striate cortex that receives input from the lateral geniculate nucleus.
trichromatic theory
Explanation of color vision based on the coding of three primary colors: red, green, and blue.
optic chiasm
Junction of the optic nerves, one from each eye, at which the axons from the nasal (inside - nearer the nose) halves of the retinas cross to the opposite side of the brain.
retina
Light-sensitive surface at the back of the eye consisting of neurons and photoreceptor cells.
visual-form agnosia
Inability to recognize objects or drawings of objects.
scotoma
Small blind spot in the visual field caused by migraine or by a small lesion of the visual cortex.
luminance contrast
The amount of light reflected by an object relative to its surroundings.
receptive field
Region of the visual world that stimulates a receptor cell or neuron.
retinal ganglion cell (RGC)
One of a group of retinal neurons with axons that give rise to the optic nerve.
sensation
Registration of physical stimuli from the environment by the sensory organs.
tectopulvinar system
Projections from the retina to the superior colliculus to the pulvinar (thalamus) to the parietal and temporal visual areas.
cone
Photoreceptor specialized for color and high visual acuity.
optic ataxia
Deficit in the visual control of reaching and other movements.
homonymous hemianopia
Blindness of an entire left or right visual field.
quadrantanopia
Blindness of one quadrant of the visual field.
rod
Photoreceptor specialized for functioning at low light levels.
facial agnosia
Face blindness - the inability to recognize faces; also called prosopagnosia.
geniculostriate system
Projections from the retina to the lateral geniculate nucleus to the visual cortex.
ocular-dominance column
Functional column in the visual cortex maximally responsive to information coming from one eye.
topographic map
Spatially organized neural representation of the external world.
striate cortex
Primary visual cortex (V1) in the occipital lobe; its striped appearance when stained gives it this name.
parvocellular (P) cell
Small-celled visual-system neuron that is sensitive to form and color differences.
blob
Region in the visual cortex that contains color-sensitive neurons, as revealed by staining for cytochrome oxidase.
visual field
Region of the visual world that is seen by the eyes.
optic flow
Streaming of visual stimuli that accompanies an observer’s forward movement through space.
cortical column
Cortical organization that represents a functional unit six cortical layers deep and approximately 0.5 millimeter square and that is perpendicular to the cortical surface.
perception
Subjective interpretation of sensations by the brain.
