Term
|
Definition
a specialized neuron that detects a particular category of physical events
Hair cells in the ear
Nociceptors in skin (pain)
Chemoreceptors (taste and smell)
Photoreceptors (vision |
|
|
Term
|
Definition
| the process by which sensory stimuli are transduced into slow, gradual receptor potentials. Sensory input such as light, pressure, pain, sound is transformed into an electrical signal and communicated to the brain |
|
|
Term
|
Definition
| a slow, graded electrical potential produced by a receptor cell in response to a physical stimulus |
|
|
Term
|
Definition
Light is a narrow band of the spectrum of electromagnetic radiation.
Electromagnetic radiation with a wavelength of between 380 and 760 nm is visible to us.
This range not qualitatively different from the rest of the electromagnetic spectrum; it is simply the part of the continuum that we humans can see. |
|
|
Term
|
Definition
| determined by wavelengh, what we think as color |
|
|
Term
|
Definition
| determined by intensity of electromagnetic radiation |
|
|
Term
|
Definition
| the purity of of the light that is being percieved |
|
|
Term
|
Definition
| cooperative, keep both eyes fixed on target |
|
|
Term
|
Definition
| the rapid, jerky, movement of eye used in scanning a visual scene |
|
|
Term
|
Definition
| the movement that the eyes make to maintain an image of a moveing object on the fovea (following your finger) |
|
|
Term
|
Definition
|
|
Term
|
Definition
| - white outer layer of eye; opaque, light cant get through (doesnt cover front of eye we see from) |
|
|
Term
|
Definition
| outermost layer at the front of the eye; allows light to pass in. |
|
|
Term
|
Definition
| pigmented ring of muscles behind the cornea which controls opening/closing of the pupil |
|
|
Term
|
Definition
| layer of cells behind the iris; changes shape depending on where person focuses- distant = flat, close = rounded. Accomedation is when lens changes shape to see distant and close images |
|
|
Term
|
Definition
| muscle fibers attached to outer edge of lens to change shape of lens to see distant and close images |
|
|
Term
|
Definition
| opening in the center of the eye that allows light to pass through |
|
|
Term
|
Definition
| back surface of the eye that is lined by visual receptors. Image on retina is inverted: light from above strikes bottom and light from below strikes top; light from left strikes right side and vice versa |
|
|
Term
|
Definition
visual receptors that are abundant in the periphery of the retina,
respond best to low light conditions,
less useful in bright light, color blind,120 million |
|
|
Term
|
Definition
visual receptors that are abundant in and around the fovea (central region of retina)
respond best to bright light conditions
essential for acute and color vision
6 million |
|
|
Term
|
Definition
| region of the retina with highest acuity; color-sensitive cones constitute the only type of photoreceptor found in the fovea. |
|
|
Term
|
Definition
| exit point from the retina of the fibers of the ganglion cells that form the optic nerve; responsible for the blind spot |
|
|
Term
|
Definition
| photoreceptor layer at back of eye, form synapses with bipolar cells, which forms synapses with ganglion cells, whose neurons travel through optic nerve and carry visual info into rest of brain |
|
|
Term
|
Definition
| a bipolar neuron in middle layer or retina, conveying info from photoreceptors to ganglion cells |
|
|
Term
|
Definition
| neuron located in retina that reiceves into from bipolar cells, its axons give tise to optic nerve |
|
|
Term
|
Definition
| neuron in the retina that interconnects adjacent photoreceptors and the outer processes of bipolar cells |
|
|
Term
|
Definition
| a neuron in the retina that interconnects adjacent ganglion cells and the inner proceses of the bipolar cells |
|
|
Term
|
Definition
| thin plates of membrane in the outer segment of rods and cones that contain photopigments |
|
|
Term
|
Definition
| a protien dye bonded to a retinal, a substance dervied from vitamin A responsible for the transduction of visual info. Consisting of an opsin (protein) and retinal (lipid) - for example, rhodopsin |
|
|
Term
| process of detection of light by photoreceptors |
|
Definition
1) lamellae (thin plates of membrane on photoreceptors) contain photopigments consisting of an opsin (protein) and retinal (lipid) - for example, rhodopsin
2) when rhodopsin is exposed to light, it breaks into rod opsin and retinal
3) when the photopigment is split, it changes the membrane potential (receptor potential), which changes the rate the photoreceptor releases its transmitter substance
4) photoreceptors have ion channels that are always open, and ions (+) freely enter the cell
5) when the photopigment splits, sodium channels close, keeping ions from entering the cell, and causing the membrane to hyperpolarize
6) this stops release of the transmitter substance
7) the transmitter substance of the photoreceptors usually causes a hyperpolarization in the bipolar cells
8) if transmitter substance release stopped, then bipolar cells depolarize and release more of their transmitter substance
9) this causes depolarization of the ganglion cell, which increases its rate of firing |
|
|
Term
| dorsal lateral geniculate nucleus |
|
Definition
| where the ganglion cells brings visual info to first in brain. This nucleus is in the thalamus. It contains 6 layers of neurons,each recieves input from only one eye |
|
|
Term
|
Definition
| inner two layers of the neurons in the dorsal lateral geniculate nucleus, transmits info necessary for form, movement, depth, and small differences in brightness to primary visual cortex and superior colliculi |
|
|
Term
|
Definition
| the four outer layers of neurons in the dorsal lateral geniculate nucleus , transmits info necessary for perception of color and fine details to primary visual cortex |
|
|
Term
|
Definition
Two pathways of visual information allow for different clinical presentations:
blindsight- connections from eyes to primary visual cortex are destroyed. Person is able to detect movement and depth without reporting “seeing” the stimulus. Person will orient eyes to movement of objects in visual field, and can in fact grab it with their hand, due to intact connections in superior colliculi. |
|
|
Term
| Visual Pathway (IMPORTANT TO MEMORIZE PATHWAY!) |
|
Definition
|
|
Term
| visual pathway color coded for visual field (left side of brain gets the info from the RIGHT HALF OF VISUAL FIELD, NOT FROM RIGHT EYE!) and vice versa |
|
Definition
|
|
Term
|
Definition
1. optic nerve
2. optic chiasm
3. optic tract
4. 5. optic radiation
A. unilateral blindness
B. bitemporal hemianopsia
C. left homonymous
hemianopsia
D. left inferior homony-
mous quadranopsia
E. left superior homony-
mous quadranopsia |
|
|
Term
|
Definition
| the portion of a visual field the neuron "sees", that is, the place in which a visual stimulus must be located to produce a alteration in the firing rate of that neuron |
|
|
Term
| What accounts for the better visual acuity in the fovea versus periphery of eye? |
|
Definition
| each ganglion cell in fovea recieve input from one bopolar cell attached to one cone. But in periphery, many cones or rods and bipolor cells attach to each ganglion cell |
|
|
Term
| the three types of ganglion cells to detect light |
|
Definition
1. ON cells-stimulated by light in center of central field and inhibited by light in surrounding field
2. OFF cells-stimulated by light in surrounding field and inhibited by light in center
3. ON/OFF cells-stimulated briefly when light turned on or off |
|
|
Term
| 3 types of cones for seeing color |
|
Definition
Trichromatic (three-color) coding: eye contains 3 types of receptors, and we see a specific color by comparing responses from 3 kinds of cones
blue cones - detect short wavelengths
green cones - detect medium wavelengths
red cones - detect long wavelengths |
|
|
Term
|
Definition
| confuse red/green; see blue and yellow and red and green look yellowish; normal acuity; because red cones are filled with green cone opsin; X-linked |
|
|
Term
|
Definition
| same perception as protanopia (confusde red and green, see them as yellowish), but green cones are filled with red cone opsin; X-linked |
|
|
Term
|
Definition
| rare, not X-linked; see world in reds and greens; have problems with blues; retinas lack blue cones; lack thereof does not affect acuity (because we have so few blue cones normally) |
|
|
Term
| 2 types of ganglion cells that percieve color |
|
Definition
At level of the retinal ganglion cell, the three-color code gets translated into an opponent-color system
Retina contains two kinds of color-sensitive ganglion cells:
red-green and yellow-blue. When red is on and green off then the cell gets excited by red and inhibited by green. Green off, red on cells get excited with green and inhibit with red.
There is also black-white cells (detect brightness) |
|
|
Term
| striate cortex (aka primary visual cortex) |
|
Definition
| where vidual info goes after ganglion cells, 25% of the cortex gets infro from the fovea (high acuity) and 75% from peripheral. Striate cortex has 6 principal layers. nuerons in striate cortex repond to orientation and movement. some respond best to horizontal line, some to vertical line and some to in between. Striate cortex also responds to spatial frequency, retinal disparity and color in addition to orientation and movement. |
|
|
Term
|
Definition
| an orientation-sensitive neuron in the striate cortex whose receptive field is organized in an opponent fashion. Receptive fields sensitive to angles (vertical, horizontal, diagonal) Excited if stimulus is presented in center of receptor field, but inhibited when moved away from center |
|
|
Term
|
Definition
| a neuron in the visual cortex that responds to the presence of a line segment with a particular orientation located within its receptive field, especially when the line moves perpendicular to the orientation. As opposed to simple cells, complex cells do respond when line is in the periphery. |
|
|
Term
|
Definition
| a nueron 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 cells receptive field. They have inhibitory regions at the ends of the lines, meaning the cells detect the location of ends of lines of a particular orientation. (pg 159 picture) |
|
|
Term
|
Definition
| the fact that points on objects are located at two different distances from each eye, therefore the object will fall of two slightly different locations on two retinas-this provides the basis for stereopsis, (being able to see depth by combining two viewpoints) |
|
|
Term
| visual pathway from striate cortex onward |
|
Definition
Visual information in the striate cortex (aka primary visual cortex) is sent to extrastriate cortex, a region of visual association cortex, which processes orientation, movement, color, spatial frequency, depth, etc. Then to…
1) ventral stream - ends with the inferior temporal cortex, involved with perception of objects ("what”)
2) dorsal stream - ends with the posterior parietal cortex, involved with perception of location and movement (“where”) |
|
|
Term
|
Definition
| the region of the visual association cortex; recieves fibers from the striate cortex and from the superior colliculi and projects into the interior temporal cortex |
|
|
Term
|
Definition
| a system of interconnected regions of visual coten involved in the perception of spatial location (where an object is located, if its moving, its speed and direction), beginning with striate cortex and ending with posterior partietal cortex |
|
|
Term
|
Definition
| a system of interconnected regionsd of visual cortec involved in the perception of form (what an object is and what color is has), beginning with the striate cortex and ending with the inferior temporal cortex |
|
|
Term
|
Definition
| the relatively constant appearance of the colors of objectgs viewed under varying conditions. Our visual systen compensates for the source of light by comparing the color composition of each point in our visual field with the average color of the whole scene |
|
|
Term
|
Definition
| the loss of color vision caused by damage to area V8 of the visual association cortex |
|
|
Term
|
Definition
| deficits in visual form perception in the absense of blindness, caused by damage to parts of visual association cortex that contribute to central stream (cant recogmize objects although can describe them and can recognize them when can hold them) |
|
|
Term
| lateral occipital complex (LOC) |
|
Definition
| a large region of the ventral stream of the visual association cortex that is involved in the perception of objects other than peoples bodies and faces |
|
|
Term
|
Definition
| failure to recognize particular people by the sight of thier face due to damage to fusiform face area in visual assocaiton cortex |
|
|
Term
|
Definition
| a region of the vidual association cortex located in the inferior temporal; involved in the perception of faces |
|
|
Term
|
Definition
| a region of the visual association cortex just posterior to the FFAl, invovled in the perception of the human body (besides faces). Damage to this causes autotopagnosia- inability to localize and orient different parts of the body |
|
|
Term
| parahippocampal place area (PPA) |
|
Definition
| a region of the medial temporal cortex, involved in perception of particular places. May also play a role in paralinguistic aspects of language (e.g., ability to detect sarcasm) |
|
|
Term
|
Definition
the person has normal visual acuity but cannot recognize an object visually by its shape, nor can they draw or copy drawings of the object.
Breakdown in the form analyzing system |
|
|
Term
|
Definition
disconnection between verbal and visual systems, Perception is relatively intact
Cannot name what they have seen and may be unaware of these perceptions (e.g., cannot come up with a mental picture). Can copy a drawing of an object, but cannot spontaneously draw an object |
|
|
Term
|
Definition
| the complex motion of points in the vidual field caused by relative movement between the observer and the enviroment e.g., how fast you are approaching objects, where you are headed, and if objects will pass on the right or left. The MST region (aka area v5) of the extrastriate cortex controls this |
|
|
Term
|
Definition
| inability to percieve monvement, caused by damage to the area V5 (MST) of the visual association cortex |
|
|
Term
|
Definition
| 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. |
|
|
Term
|
Definition
deficit in awareness and attention to one side of space (the side opposite where the stroke occurred in the brain); usually occurs following stroke affecting dorsal stream in right parietal lobe
Patients will avoid looking to one side of room, dress only one side of body, shave only one side of face, cannot find objects on neglected side of space |
|
|
