Special Sub-Topic: Me, Myself, and Eye
|Which of the four lobes of the brain is primarily responsible for vision?|
Occipital Lobe. The Occiptal lobe is also responsible for the color and motion of objects, and is located at the posterior (rear) portion of the brain above the cerebellum.
|Which part of the retinas projects information from the ipsilateral (same side) visual fields to the contralateral (opposite side) hemisphere of the brain?|
Nasal. The nasal portion of the retina is located on the inside part of the retina, while the temporal portion is located on the outside; the rostral part does not exist. And this function it serves is done through the optic nerve; The left and right optic nerves of the eye cross at an area called the optic chiasm.
|What is the correct order of the primary visual pathway in the brain?|
Retina, Lateral Geniculate Nucleus (LGN), Striate Cortex (V1). 90% of all visual information in the brain uses this pathway. The LGN and MGN are parts of the thalamus. The LGN is for vision, and the MGN is for hearing. The superior colliculus is part of the secondary visual pathway. The retina, fovea, and cornea are basic anatomical visual structures. Brodmann area 17, the striate cortex (V1), and the calcarine sulcus are the same thing, the primary visual area in the brain. Finally, the arcuate fasciculus is a fiber tract connecting Broca's and Wernickes' area, which are for speech.
|Which of the following can a lesion to the primary visual cortex (V1) or optic tract cause?|
Scotoma. A scotoma is basically a blind spot in the visual field of either, or both, eyes caused by some type of cerebral, usually V1, or nerve damage. This type of problem leads to a loss of a part, or parts, of a persons visual field.
|What characterizes the visual impairment known as akinetopsia?|
Impaired motion perception due to cortical damage. Akinetopsia has been described by patients as seeing the world as a series of snapshots with no motion whatsoever. For example, one second they are pouring a cup of coffee, and without realizing it the cup overflows because they didn't see the liquid in motion.
|Which of the following is a subtype of visual agnosia that is essentially a failure to organize a coherent perception of an object because of a breakdown of object constancy?|
Apperceptive Agnosia. In this form of agnosia, the patient is only able to recognize objects from a particular point of viewing. If the object is turned, or rearranged in any manner, the patient will fail to recognize it.
|Which of the following pathway and lobe pairs is the one that is associated with identifying what an object in the enviroment is?|
Ventral Pathway, Temporal Lobe. This has been shown through increased activity in the temporal lobe during object discrimination tasks. Also, the dorsal pathway and parietal lobe pair are associated with locating where an object in the enviroment is; I made the others up.
|In the primary visual cortex (V1) of the brain there are layers that code for only specific visual information. Within layers one and two there are darker areas that are known as blobs. What chemical causes these blobs to be darker?|
Cytochrome Oxidase. Cytochrome oxidase is an enzyme found in blobs that gives them their darker color. Also, blobs have a high metabolic rate and are coded in layers one and two of the primary visual cortex (V1) from projected information from either layer three or five of the lateral geniculate nucleus (LGN).
|Which of the following is a category specific visual deficit exemplified by the patient being unable to recognize faces?|
Prosopagnosia. The ability to recognize faces is thought to have an evolutionary purpose; so we can tell each other apart and to recognize those who are friendly, and vice versa. The area of the brain that is mostly responsible for facial recognition is the Fusiform Face Area (FFA) in the medial, inferior temporal lobe.
|Which of the following degrees of orientation of a stimulus does a simple cell of the visual cortex get most activated by?|
45 Degrees. A simple cell in the visual cortex combines its input from multiple different Lateral Geniculate Nucleus (LGN) cells. Moreover, a simple cell of the visual cortex is a fundamental part of shape perception in that it detects the borders of objects.
Did you find these entries particularly interesting, or do you have comments / corrections to make? Let the author know!
Send the author a thank you or
Submit a correction