Visual System Flashcards
Rods:
___ sensitivity
Specialized for ____ vision
____ photopigments per cell vs cones = captures ____ light
____ temporal resoluation, _____ response, ____ intergration time
More sensitive to _____ light
Saturates in ______ light
_____ acuity, ____ convergent pathways
in the fovea, _______
_chormatic
RODS:
HIGH senitivity
specialized for NIGHT vision
HIGH amplification, single photon detetion
LOW temporal resolution, SLOW response, LONG intergration
more sensitive to SCATTERED light
SATURATES in DAY LIGHT
LOW ACUITY, highly convergent pathways
ABSENT in central fovea region
ACHROMATIC, only one type of photopigment in rods
CONES:
____ sensitivity
specialized for ____ vision
_____ photopigment per cell vs rods
____ aplication per cell vs rods
_____ temporal resolution, ____ response, ____integration time
most sensitive to _______ stimulation
Saturates only in _______
____ acuity, less convergence of retinal pathways, esp in____
___chromatic; ____ types of cones
CONES:
LOWER sensitivity
specialized for dAYLIGHT vision
LESS photpigments per cell than rods
HIGH temporal resolution, fast response, short integration time
most sensitive to DIRECT AXIAL STIMULATION
Saturated only in INTEENSE light
High acuity, less convergence of retinal pathways, ESP IN FOVEA
CHROMATIC w/ THREE TYPES OF cones, each with a pigment sensitive to a differnet part of the visible spectrum of light
The first action potentional ocurs in the axon of the _______.
Is there AP in rods and cones??
The first AP is in the AXON of the ganglion cells
there is NO AP in rods and cones
Only ___ exist at the fovea.
The foveola is an _____ zone.
Only CONES exist at fovea. Area of highest visual acuity and best color.
The foveola is an AVASCULAR zone
The path of light:
Light enters the eye….
Light goes passes through all the layers until reaching Rods/Cones –> interneurons –> ganglion cells
Ganglion cell axons then form the optic nerve
Neural pathway from Retina:
Optic Nerve –> Optic Chiasm (nasal retinal axons cross) –> optic tract –> lateral geniculate nucleus (thalamus) –> optic radiations (geniculocalcarine tract) –> visual cortex
Ganglion Cells:
M-type:
Size: ____ cell bodies w/ _____ arborization
_____ receptive fields
respond best to _____ and _____ objects
Rods or Cones?
P-Type:
Size: ____ cell bodies, ____ relation
____ receptive fields, mostly seen in ___ area of the eye
respond best to _____ and _____
Rods or cones?
M-Type:
LARGE cell bodies, DENSE aborization; LARGE receptive fields, transient response to continuous light (rapidly adpating); respond best to MOVEMEMNT, and LARGE objects; RODS
P-type:
SMALL cell bodies, 1:1 ratio to cones; SMALL receptive fields; more numerous near fovea; wavelength selective (color), responds best to COLOR and FINE DETAIL; CONES
Where does perception begin?
Primary visual cortex / area 17 / striate cortex / V1
(some info enters the brainstem via the pretectal area for pupillary refelxes and superior colliculus for head and eye movements)
How can you test if the optic nerve is functional in an eye?
How is the light traveling through this test?
Testing both eyes –>
Pupillary light reflex.
Light enters via one pupil –> optic fibers through the brachium of the superior colliculus –> Edinger-westphal nucleus in the pretectal area –> preganglionic fibers of CN III to the ciliary ganglion –> sphincter pupillae muscle
Tetsing both eyes confirmes that the rostral midbrain is functional
Optic Nerve Damage:
_____ sized pupils
_____ responds to light shone in the eye ipsilateral to the lesion and ______ respond to light shone in the contralateral eye
EQUAL pupils
NEITHER respond to light shone in the eye ipsilateral to lesion
BOTH respond to light shone in the contralateral eye
Oculomotor Nerve Damage:
______ ipsilateral pupil that ______ respond to light shone in either light
DILATED IPSILATERL pupil, while other pupil constricts normally
DOESNOT respond to light shone in either eye
Horner’s Syndrome
LOSS of ______ input —> (3 main SX) _____ to lesion
loss of SYMPATHETIC input to the head will result in MEIOSIS (constricted) pupil, PTOSIS of eyelid, ANHYDROSIS (loss of sweating), IPSILATERAL to the lesion
Accomodation = changing gaze to focus on a nearby object by:
vergence of eyes via ______
thickening of lens via ______
constriction of both pupils
Involves (3)
Vergence of eyes via CONTRACTION OF BOTH MEDIAL RECTI M
Thickening of lense via CILIARY MUSCLE CONTRACTION (therefore releases tension on the zonular fibers)
CONSTRICTION of both pupils (improves optical performance and reduces light entering the eye)
Retina, lateral geniculate body and visual cortex (since conscious act)
Corneal Eye Blink Reflex:
VS
Visual Blink Reflex:
Corneal Eye Blink Reflex: CN V –> internerurons of the reticular formation –> looping through CN VII –> orbicularis oculi
Visual Blink Reflex: CN II –> different pathway –> CN VII
Information in the primary visual cortex is processed in ____ specialized columns called ______. The columns are….
Each layer projects to other sites in the CNS via large ______ cells.
Integration and convergence continue as info ____ allowing the fomration of complex and abstract perceptions and assocations
Info is processed in THREE specialized columns called the HYPERCOLUMS
- Orientation - spaitial representaiton/edges
- Blobs - color specificity
- Occular dominance - left vs right
each layer projects to other sites via large PYRAMIDAL cells
Info ASCENDS allowing for the formation of complex/abstract perceptions and assocations
