130 Discussion Questions — Part B 



DISCUSSION QUESTIONS— PART B 



1. The cell wall of the alga Nitella conducts spike potentials similar to 

 those found in nerve and muscle fibers. Describe the equipment necessary 

 to test the dependence of spike height on K + concentration. What are the 

 results of such experiments? 



2. Some of the evidence for the activity of acetylcholine in nerves is based 

 on studies of the electrical eels. Describe the electrical organ of Torpedo, 

 in the terminology of anatomy, histology, electricity, and biochemistry. 



3. The terms "spatial summation" and "temporal summation" are used to 

 describe some of the phenomena called "synaptic computation" in Chapter 4. 

 What is the experimental evidence which shows that these occur ? 



4. Describe how one can show that at the giant synapse in the crayfish, 

 transsynaptic conduction is a purely electrical phenomena, whereas in the 

 human spinal cord it is mediated by special transmitter substances. 



5. The compound GABA, gamma aminobutyric acid, has been found to 

 occur in large amounts in the central nervous system and to inhibit trans- 

 synaptic conduction. What is the evidence for its action? What is the 

 relationship of GABA to the computation-like functions of the nervous system? 



6. The feedback loops controlling the iris have been studied anatomically 

 and from the point of view of a servomechanism. Describe both in more 

 detail than given in the text. Most servomechanisms can be stimulated at 

 their characteristic frequency and caused to oscillate. How was it demon- 

 strated that iris control can be caused to oscillate in a similar fashion ? 



7. What is an autocorrelator ? What is the relationship between the auto- 

 correlation function and the Fourier transform? Use this to demonstrate 

 why the autocorrelator is useful for electroencephalographic studies. 



8. What special precautions must be taken in constructing electroencephalo- 

 graphic amplifiers? Describe a practical electronic circuit for such an 

 amplifier and analyze its action. 



9. Various mathematical theories have been proposed to describe the 

 motion of the cochlea. Describe the essential features of the theory developed 

 by Fletcher. Be sure to note all approximations which have been made. 



10. What is known about the lateral line organs of fish ? 



11. Many moths have only a limited number of nerve fibers associated 

 with their hearing organs. What is the evidence that only these fibers are 

 active? How might one try to reconcile this with the moth's ability to avoid 

 bats? 



12. Describe a recent experiment using arm analogs of the cochlea to 

 study hearing. 



