Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
36 Cards in this Set
- Front
- Back
organization of sensory cortex
|
primary (exists for each modality), nonprimary/secondary (receives direct projection from corresponding primary sensory cortex area)
|
|
primary somatosensory cortex / somatosensory 1 / S1
|
located in postcentral gyrus, receives touch info from opposite side of body
|
|
primary motor cortex / M1
|
located in precentral gyrus, executes movement (motor control)
|
|
flexibility of sensory brain regions
|
association areas (process mixture of inputs from different modalities), polymodal neurons (allow different sensory systems to interact), synesthesia (stimulus in one modality creates sensation in another)
|
|
encoding of sensory events
|
as streams of APs; stimulus location determined from position of activated receptors; receptive field: stimulus region that affect activity of a cell in a sensory system (i.e. neuron's firing rate)
|
|
adaptation
|
decline in receptor sensitivity to maintained stimulation
|
|
suppression of info
|
remove stimulus, central modulation of sensory modulation (higher brain centers suppress/amplify sensory inputs)
|
|
major roles of eye
|
refraction (focus light from outside body), transduction (light waves > neural signals), transmission (of signals to brain)
|
|
refraction
|
light passes through CORNEA (transparent outer layer), forms image on RETINA (receptive surface inside eye) via LENS, passes through AQUEOUS HUMOR (fluid behind cornea), regulated by IRIS and PUPIL, passes through VITREOUS HUMOR (fluid between lens and retina)
|
|
focusing images on retina
|
ciliary muscles (control shape of lens) control accommodation (adjustment of lens to focus), an automatic involuntary muscular movement
|
|
common refraction problems
|
cataracts (opacities in lenses), presbyopia (far-sightedness due to insufficient accommodation), hyperopia (far-sightedness due to short eyeball), myopia (nearsightedness due to long eyeball),
emmetropia (perfect vision), astigmatism (unequal curving of one eye |
|
photoreceptors
|
sensory neurons that transduce light into graded neural signals; rods and cones
|
|
bipolar cells
|
rods/cones > ganglion cells
|
|
ganglion cells
|
cells whose axons form optic nerve
|
|
optic nerve
|
collection of ganglion cell axons extending from retina to brain
|
|
scotopic vs. photopic systems
|
rods (dim light, insensitive to color) vs. cones (requires more light, allows color vision)
|
|
convergence
|
specific to rods
|
|
fovea
|
central portion of retina, containing highest density of photoreceptors (cones); receives direct light input that doesn't pass through other cells of blood vessels, center of gaze
|
|
peripheral retina
|
rods:cones >20
|
|
blind spot
|
where optic nerve leaves retina
|
|
sensitivity vs. acuity
|
rods, quantitative input vs. cones, qualitative input
|
|
electromagnetic spectrum
|
continuum of electromagnetic energy; visual light ranges 400-700nm
|
|
wavelength
|
distance between peaks of waves, used to describe light energy
|
|
transmission
|
retina > optic nerve > crosses optic chiasm, now called optic tract > superior colliculus or lateral geniculate nucleus, latter > visual cortext
|
|
crossing at optic chiasm
|
info from each visual hemifield sent to controlateral hemisphere of occipital lobe
|
|
retinal receptive field
|
# of photoreceptors that feed into a ganglion cell
|
|
light hyperpolarizes photoreceptors
|
causes decreased release of glutamate
|
|
on-center bipolar cells
|
excited by light in center of its receptive field
|
|
off-center bipolar cells
|
inhibited by light in center of receptive field
|
|
bipolar cells also release glutamate
|
causes depolarization in ganglion cells
|
|
lateral inhibition
|
process in which sensory receptor cells inhibit info from neighboring cells
|
|
bipolar vs. ganglion cell response
|
changes in local membrane potentials vs. action potentials
|
|
simple cortical cells
|
respond best to bars of light of a particular width, certain orientation, and particular location in visual field
|
|
complex cortical cells
|
respond best to movement of bars of light in particular orientation, an in preferred direction
|
|
varied receptive fields (V#)
|
1 - lines or bars, 2 - illusory contours, complex relations among parts of receptive fields 4 - concentric, radial stimuli; color differences, IT - particular complex forms, 5 - moving visual stimuli
|
|
visual cortex processing streams
|
ventral, temporal lobe (what - identification); dorsal, parietal lobe (where - location)
|