Neurobio exam 2 ch 9

Receptive field

Region of sensory space (e.g. skin surface) in which a stimulus modifies a receptor's activity

topographic map

spatially organized neural representation of the external world

Sensation

Registration by the sensory organs of physical stimuli from the environment

Perception

subjective interpretation of sensations by the brain

Retina

Light-sensitive surface at the back of the eye consisting of neurons and photoreceptor cells

Photoreceptor

specialized retinal neuron that transduces light into neural activity

Fovea

Central region of the retina specialized for high visual acuity; it's receptive fields are at the center of the eyes visual field

Blind spot

Retinal region where axons forming the optic nerve leave the eye and where blood vessels enter and leave; has no photoreceptors and is thus said to be blind

Rod

photoreceptor specialized for functioning at low light levels

Cone

photoreceptor specialized for color and high visual acuity

retinal ganglion cells (RGCs)

one of a group of retinal neurons with axons that give rise to the optic nerve

magnocellular cells

large visual system neuron sensitive to moving stimuli

parvocellular cells

small visual system neuron sensitive to differences in form and color

optic chiasm

junction of the optic nerves, one from each eye, at which the axons from the nasal halves of the retinas cross to the brain's opposite side

geniculostriate system

projections from the retina to the lateral geniculate nucleus to the visual cortex

striate (striped) cortex

primary visual cortex (V1) in the occipital lobe; shows stripes (striations) on staining

tectopulvinar system

projections from the retina to the superior colliculus to the pulvinar (thalamus) to the parietal and temporal visual areas

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.

ventral stream

visual processing pathway from V1 to the temporal lobe for object identification and perceiving related movements

dorsal stream

visual processing pathway from V1 to the parietal lobe; guides movements relative to objects

cortical column

Anatomic organization that represents a functional unit six cortical layers deep and approximately 0.5 mm square, perpendicular to the cortical surface.

primary visual cortex (v1)

striate cortex in the occipital lobe that receives input from the lateral geniculate nucleus

extrastriate cortex (v2-v5)

visual cortical areas in the occipital lobe outside the striate cortex

Blob

Region in the visual cortex that contains color-sensitive neurons, as revealed by staining for cytochrome oxidase.

facial agnosia

Face blindness-the inability to recognize faces; also called prosopagnosia

luminance contrast

the amount of light an object reflects relative to its surroundings

ocular dominance columns

functional column in the visual cortex that is maximally responsive to information coming from one eye

trichromatic theory

Explanation of color vision based on the coding of three primary colors: red, green, and blue.

opponent-process theory

Explanation of color vision that emphasizes the importance of the apparently opposing color pairs: red vs green, blue vs yellow

color constancy

phenomenon whereby an object's perceived color tends to remain constant relative to other colors, regardless of changes in illumination

homonymous hemianopia

blindness of an entire left or right visual field

Quadrantanopia

blindness of one quadrant of the visual field

scotoma

small blind spot in the visual field caused by migraine or by a small lesion of the visual cortex

visual form agnosia

inability to recognize objects or drawings of objects

optic ataxia

deficit in the visual control of reaching and other movements

The explanation of color vision based on the coding of 3 primary colors is called ...

Trichromatic theory

... allow sensory systems to interact

Receptive fields

... is the experience of sensation

Perception

The ventral visual stream is considered the "what" stream and the dorsal visual stream is considered the "..." pathway

How

Just before entering the brain, the optic nerves in each eye partly cross creating the

Optic chiasm

... are the energy filters that transduce incoming physical energy into neural activity

Receptor neurons

Neural coding of location begins in the _____ and is maintained throughout all visual pathways.

Retina

The ... sends information to a disproportionately large part of the occipital cortex

Fovea

Each retinal ganglion cell responds only to the presence or absence of _____.

Light

the amount of light an object reflects relative to its surroundings is called ...

Luminance contrast

Damage to the fusiform face area can result in ...

Facial agnosia

Blindness of the entire left or right visual field is called _____.

homonymous hemianopia

... is a deficit in the visual control of reaching and other movements

Optic ataxia