Visual Pathways and Eye Movements Flashcards
Visual stimuli are ultimately relayed to the primary visual cortex via the thalamus.
The primary visual cortex is aka the _____ cortex, located on the upper and lower banks of the _____ sulcus, which is Brodmanns area _____
Striate; calcarine; 17
The visual pathway ends in the primary visual cortex retinotopically. What does this mean for inferior vs. superior visual fields?
Inferior visual fields project above calcarine sulcus
Superior visual fields project below calcarine sulcus
The visual association cortex is known as the extrastriate cortex, composed of brodmanns areas ____ and _____ which surround the striate cortex and comprise the rest of the ______ lobe, as well as related parts of the temporal and parietal lobes. It is heavily interconnected with brodmanns area 17.
18; 19; occipital
The _____ nucleus also sends targets to the visual association cortex which helps interpret location, motion, form, and color
Lateral geniculate
What are 2 visual cortices besides the striate and extrastriate?
Superior colliculus
Pretectal/pretectum area
Function of superior colliculus as visual cortex
Spatially directs head movements and visual reflexes
2 sources of input to superior colliculus as visual cortex
Retinal input = select fibers from each optic tract bypass the LGN, passing over the medial geniculate nucleus and terminating retinotopically in superior colliculus
Cortical input = cells in Brodmann 17 project to superior colliculus in retinotopic pattern
[also receives some spinotectal/somatosensory and auditory inputs]
The prectectum area is a bilateral group of interconnected nuclei located near the midbrain-forebrain junction. What are the 3 input sources for the pretectum as a visual cortex?
Afferent bilateral fibers from the optic tract
LGN and suprachiasmatic nucleus
Function of pretectum area as a visual cortex
Pretectal nuclei respond to varying intensities of illuminance, mediating non-conscious behavioral responses to acute changes in light
Area that you see when both eyes are fixed in one position
Visual field
Within the visual field, the object of attention is focused and centered at the location of ____ and ____
Fovea centralis
Macula lutea
The macula lutea is lateral to the ____ ___ which is the region where the retinal axons leave the eye as the optic nerve, and the area where photoreceptors are absent (blind spot)
Optic disk
The macula is represented more _______ in the brain, in the region of the occipital pole, while peripheral visual fields are represented more ______
Posteriorly; anteriorly
Visual field is subdivided into what 2 zones?
Binocular zone = broad central region seen by both eyes
Monocular zones (R/L) = seen only by corresponding eye
Location on the retina that an object in the visual field is projected
Retinal field
Divisions of the retinal field
Nasal half (upper quadrant + lower quadrant)
Temporal half (upper quadrant + lower quadrant)
Image formed on the retina is inverted in both ____ and _____ dimensions
Lateral; vertical
The image formed on the retina is inverted in both lateral and vertical dimensions
For example:
The left half of the visual field forms an image upon the ______ half of the left retina and the _____ half of the right retina
Nasal (right); temporal (right)
The 2 optic nerves partially decussate in the optic chiasm. The ___ half of each retina projects to the contralateral optic tract. The ____ half of each retina projects to the ipsilateral optic tract
Nasal; temporal
What is the functional purpose of the decussation of the optic nerve?
Depth perception
____ ____ = fibers from temporal retina (ipsilateral eye) + fibers from nasal retina (contralateral eye)
Optic tract
The optic tract curves posteriorly around the _____ _____ to terminate in the ______ ____ nucleus
Cerebral peduncle; lateral geniculate
The lateral geniculate nucleus consists of six layers of ______ fibers which terminate in a precise retinotopic pattern.
The ventral base is formed by incoming optic tract (retinogeniculate) fibers, while the dorsal and lateral borders are formed by the outgoing _____ _____
Myelinated
Optic radiations