Module 3 - Vision Flashcards
4 sensory systems
olfactory, audition, visual, and somatosensory
what are sensory receptors
transduce energy from environment into neural activity
receptive field
a sensory space in which a stimulus modifies a receptor’s activity
produces patterns/maps
brain uses to identify sensory info
neural relays
the idea that receptors connect to cortex through sequence of connecting neurons sharing information
sensory coding
after being transduce, information from sensory systems is encoded by action potentials that travel along nerves until entering spinal cord/brain
topographic map
neural-spatial representation of sensory world
what part of electromagnetic spectrum can humans see
visual light (400-700nm)
sclera
the white of the eye
cornea
clear outer covering
bends light upon entering the eye
iris
colored area of eye
opens/closes to allow light in through the pupil
pupil
black part of eye where light enters
lens
focuses and bends light after the cornea
retina
where light energy initiates neural activity
fovea
the centre of there retina
high density of photoreceptors specialized for color
specialized for high visual acuity
optic disc
where blood vessels enter the eye
where nerves from optic nerve leave the eye
no receptors and is where blind spot is located
blind spot
no receptors
in optic disc
location is different in each eye - right eye can see left eye’s blind spot and vice versa
myopia
nearsightedness
cannot see far away things
light falls short of retina
hyperopia
farsightedness
cannot see close things
light falls beyond retina
2 main types of retinal neurons
bipolar and ganglion cells
characteristics of retinal neurons
translucent, not light sensitive, located at the front of retina
2 types of photoreceptors
rods and cones
characteristics of photoreceptors
located at back of eye, work with retinal neurons to translate light into action potentials, discriminate wavelengths to create colours etc.
characteristics of rods
low light specialization
more numerous than cones
longer and cylindrical
characteristics of cones
responsive to low light
less numerous than cones
specialized for colour and high visual acuity
three types of cones
s cones (small = blue light) m cones (medium = green light) l cones (long = red light)
two types of retinal ganglion cells
m cells and p cells
characteristics of m cells
large
receive input from rods
sensitive to light, not color
found throughout retina and periphery
sensitive to movement
characteristics of p cells
small, found mostly in fovea
receive in put from cones
sensitive to color, not light
sensitive to differences in form
optic chiasm
junction of optic nerves
where the optic nerves cross before entering the brain after exiting each eye
three pathways from retina to lobes in brain
geniculostriate system
tectopulvinar system
retinohypothalamic tract
two possible streams to lobes after apthways
dorsal (parietal lobe) and ventral (temporal lobe)
visual field
what is seen by the eyes
divided into right and left visual fields
input from right visual field goes into left hemisphere and vice versa
how is neural excitation demonstrated
an increase in firing
how is neural inhibition demonstrated
a decrease in firing
where is shape constructed
in the cortex from information that ganglion cells pass on about events in their receptive fields
why is shape not constructed in retina
receptive fields are too small
