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Chapter 12: Visual System II: Central Visual Pathways

A routine magnetic resonance imaging scan reveals the presence of a tumor situated in the left optic tract proximal to the lateral geniculate nucleus. The patient complains of a reduction in his field of vision. Which of the following best characterizes the likely visual deficit?

A. Total blindness of the left eye

B. Bitemporal hemianopsia

C. Right homonymous hemianopsia

D. Left homonymous hemianopsia

E. Left homonymous quadrantanopia

C. Disruption of optic tract fibers destined for the lateral geniculate nucleus will cause a homonymous hemianopsia because it affects fibers arising from the temporal retina of the ipsilateral side and from the nasal retina of the contralateral side. Because the damage occurred in the left optic tract, the loss of vision is reflected on the right visual field (ie, the left temporal retina is associated with the nasal or right visual field of the left eye, and the right nasal retina is associated with the temporal or right visual field of the right eye). Therefore, such a lesion would result in a right homonymous hemianopsia.

After a stroke, a patient appears to have normal visual acuity but is unable to recognize faces. Where is the lesion likely to be?

A. Left parietal lobe

B. Right parietal lobe

C. Inferior left temporal lobe

D. Inferior right temporal lobe

E. Occipital lobe

D. Face identification is particularly dependent on a right temporal lobe area called the fusiform face area. Damage to the parietal lobe would result in visual apraxia, whereas occipital lobe damage would tend to compromise multiple visual functions.

A patient shows up in clinic with only the right side of his face shaved and complains that he ran into the left side of his garage when parking his car at home the previous evening. Where is the lesion likely to be?

A. Left parietal lobe

B. Right parietal lobe

C. Inferior left temporal lobe

D. Inferior right temporal lobe

E. Occipital lobe

B. The patient is exhibiting left-sided hemineglect, which is caused by a parietal lobe lesion on the right side. Right-sided hemineglect, due to lesions on the left ...

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