242 Chapter 8
- Recent studies suggest that medial temporal lobe activity is
needed for memory retrieval. What is the difference between
memory storage and retrieval, and what scientific evidence
might allow them to be distinguished? - Much has been made (particularly by left-handers) of the
fact that Leonardo da Vinci was left-handed. Do you think
his accomplishments are in any way related to his left-
handedness? Why or why not? - People under chronic stress can suffer atrophy of their
hippocampi. How does this affect their ability to learn, and
what type of learning would be most affected? What type
would be less affected? Explain. - Which stroke victim is more likely to have impaired speech, the
one with paralysis on the right side or the one with paralysis on
the left side? Explain. Speculate on what changes might occur
in the brain to allow gains to be made in speech recovery. - Neurologists have noticed that patients with lesions
(damage) at the junction of the midbrain and diencephalon
of the forebrain had trouble arousing themselves from sleep.
In other patients, lesions in the lateral hypothalamic area
produce severe sleepiness, even coma. Identify the brain
system impaired by these lesions and explain how these
effects could be produced.
Test Your Quantitative Ability
Table 7.3 (chapter 7), page 000, provides the axon diameters and
conduction velocities required to answer the following questions.
Suppose, in a knee-jerk reflex, the sensory axon and motor axon
extending between the muscle and spinal cord is each 16 inches
long. The sensory axon has a diameter of 17 m m, and the motor
axon has a diameter of 9 m m. Given that there are 2.54 cm per
inch, and that a rate of 1 m/sec is equal to 2.24 miles per hour,
answer the following questions.- What is the length of each axon in centimeters and meters?
- What is the rate of conduction of the sensory axon in meters
per second and in miles per hour? - What is the rate of conduction of the motor axon in meters
per second and in miles per hour? - How long will it take, in seconds and milliseconds, for an action
potential to be conducted the length of the sensory axon? - How long will it take, in seconds and milliseconds, for an
action potential to be conducted the length of the motor axon? - Suppose the time from the start of action potentials in the
sensory neuron and the end of action potentials in the motor
neuron was measured to be 15 msec. How much time was
required for synaptic transmission?
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