visual pathway Flashcards
(35 cards)
What is the innermost layer of the eye responsible for initiating visual processing?
Retina
The retina contains photoreceptors that convert light into neural signals.
What are the key anatomical layers of the eye from superficial to deep?
- Pigment Epithelium
- Rods and Cones
- Bipolar Cells
- Ganglion Cells
- Optic Disk
- Optic Nerve (CN II)
Each layer has a specific function in the visual processing pathway.
What type of vision do rods primarily support?
Scotopic vision
Rods are highly sensitive to light but do not detect color.
What type of vision do cones primarily support?
Photopic vision
Cones detect color and detail and are less sensitive to low light.
What is the function of the tapetum?
Reflects light back through the retina to enhance light detection
This adaptation is particularly important for nocturnal animals.
Fill in the blank: The optic nerve carries visual information to the _______.
brain
What occurs at the optic chiasm?
Partial decussation of nasal fibers
This crossing ensures that the left visual field is processed in the right hemisphere and vice versa.
What is the primary role of the Lateral Geniculate Nucleus (LGN)?
Primary relay for conscious visual processing
The LGN segregates visual data by function, such as movement and shape/color.
What is the function of the visual association areas in the brain?
Integrate color, motion, context → form meaning, recognition
Final interpretation of visual input occurs here.
Which brain region is responsible for the Pupillary Light Reflex (PLR)?
Pretectal Nuclei
The PLR remains intact even in cases of cortical blindness.
What is the role of the Rostral Colliculi?
Coordinate reflex head/eye movements
This includes the Visual Grasp Reflex and does not require conscious vision.
What input does the Suprachiasmatic Nucleus (SCN) receive?
Input from retina
This input helps set circadian rhythms and influences sleep-wake cycles.
True or False: Visual deficits may affect the Pupillary Light Reflex.
False
PLRs test brainstem reflexes and can remain intact despite visual deficits.
What happens in blindsight?
Ability to reflexively respond to visual stimuli without conscious perception
This can occur due to lesions in the optic tract or cortex.
Fill in the blank: Information from the left visual field is processed by the _______ LGN and _______ cortex.
right, right
ten steps of the visual pathway
- cornea
- aqueous humor –> pupil –> lens –> vitreous body
- retina (photoreceptors
- bipolar cells –> ganglion cells
- optic nerve
- optic chiasm (partial decussation (nasal fibers))
- optic tract (towards dencephalon)
- LGN (thalamus)
- optic radiations
- primary visual cortex
primary visual cortex
receives organized image data; detects light, shape, position
visual association areas (parietal and temporal)
integrate color, motion, context –> form meaning, recognition
final interpretation of “what” is seen occurs here
LGN
Pre-cortical segregation of information (movement vs form)
visual pathways beyond conscious vision (they remain in tact even in cortical blindness)
Pretectal Nuclei - PLRs
Rostral Colliculi - reflexive head/eye movements (visual grasp reflex)
suprachiasmatic nucleus (SCN) - circadian rhythms, hypothalamus
what is the first cell type to become the optic nerve?
ganglion cells
what are the axons called from the pretectal nuclei
edinger-westphal nucleus (parasympathetic III)
*then travel –> ciliary ganglion –> pupil constriction (both eyes)
rostral colliculi output
medial longitudinal fasciculus
tectospinal tract
which tract is responsible for head movement in response to vision?
tectospinal tract
