Topic 5: Sensory – Motor Systems 3: Visuomotor Coordination
1. Where do the optic nerves cross over to become optic tracts? Do all axons
coming off the retina cross over? Explain.
The optic nerves from the left and right eyes leave the retina at the optic
disk in the back. They travel to the optic chiasm where the nerves from
each eye come together. Axons from the nasal side of the eyes cross, while
those from the temporal side do not cross. At this point the optic nerve
becomes the optic tract
2. What are the first two and the last four layers of the LGN (lateral geniculate
nucleus – target cells in the optic tract) called?
The first two layers (most ventral) are the magnocellular (large cell) layers
and layers four through six are called parvocellular (small cell) layers
3. Agnosia may be defined as _________ and is a condition effecting people with
lesions in _____________.
Agnosia may be defined as the inability to recognize (show complete
neglect of the contralateral side of the body, objects and drawings) and is a
condition effecting people with lesions in the right angular gyrus
(nondominant hemisphere) just behind area 7
4. When vision allows us to identify objects as well as note their movement in
space, we are using _________ sense.
Vision allows us to identify objects in space and to determine their
movements, this is considered an exteroceptive sense
5. Two people witnessed the same car accident, yet had two different
perceptions of the event. What could explain the phenomenon?
One of the most important aspects of sensory processing is choosing the
inputs that are most important for an individual to attend to in a given