QUIZ 1: February 16, 1999

There is only 1 best answer per question.

    Numerical questions

  1. How many µ in 1 nm (ie 1 nm = ?? µ)?
    a.1e-3 µ
    b.1e-2 µ
    c.1e-1 µ
    d.1e2 µ
    e.1e3 µ
    @ a

    Dendrite, axon and synaptic cleft are 3 structures that transmit information in the nervous system. They work at vastly different scales: 1 mm for dendrite, 1 m for axon, 20 Angstroms for synaptic cleft. Transmission rate for an axon is about 50m/s, for a dendrite about 500µ/5ms. The following questions explore relationships between signals in these structures.

  2. Assuming a 1 mm dendrite, and 1 m axon, what is the proportion of axon signal time to dendrite signal time (ie time to get down axon divided by time to get down dendrite)
    a.1
    b.2
    c.3
    d.0.5
    e.0.1
    @ b. to get down dendrite is 10 ms. To get down axon 1e3ms/50=20 ms

  3. Assuming that a chemical synapse transmits its information in 0.5 ms. How 'fast' (what rate or velocity) does the chemical cross the cleft.
    a. 0.2 µ/s
    b. 2 µ/ms
    c. 4 µ/ms
    d. 4 µ/s
    e. 2 µ/s
    @ d. 20A/0.5ms=40e-10m/1ms=40e-7m/s=4e-6m/s

  4. 5310 =
    a. 1101102
    b. 1100112
    c. 1101012
    d. 110012
    e. 101012
    @ c

  5. 10011002 =
    a. 7610
    b. 7310
    c. 8410
    d. 15210
    e. 3810
    @ a

  6. The diagram above illustrates some of the thalamic circuit that interacts with the cortex. Let's consider the signal progression from cortical pyramical cell to thalamic reticular cell to thalamic relay cell to cortical pyramical cell. Overall this feedback loop would be:
    a. positive feedback
    b. negative feedback
    @ b

  7. Now consider the fact that the thalamic relay cell can respond to negative (ie hyperpolarizing) input with initial reduction in firing (inhibition) followed by late increase in firing (facilitation). Now, what would be the sequence of effects in the feedback loop.
    a. always negative
    b. always negative
    c. negative early, positive late
    d. positive early, negative late
    e. no feedback
    @ c

    Make the following identifications of locations in the brain from the above diagram:

  8. structure #4
    a. thalamus
    b. basal ganglia
    c. hippocampus
    d. cortex
    e. cerebellum
    @ c

  9. structure #2
    a. thalamus
    b. basal ganglia
    c. hippocampus
    d. cortex
    e. cerebellum
    @ a

  10. Relays information from most sensory systems
    a. structure #1
    b. structure #2
    c. structure #3
    d. structure #4
    e. structure #5
    @ b