理工学部、建築・環境学部教養学会主催ミニ講演会
第５９回理科系学生のための公開英語講演会
Pavlov’s Dogs:
What Does Animal Behavior Teach Us?

講師：理工学部、数理・物理コース
北村　美一郎

 

“When you imagine Umeboshi, you might salivate even without eating it. You know that Umeboshi is very sour. You have learned it through experience.” As this statement by Doctor Kitamura shows, classical conditioning (Pavlovian conditioning) is quite a familiar phenomenon that we see and experience in our everyday life. The lecturer also points out that the research on classical conditioning has such possible useful applications as treatment for people’s trauma through erasure of memory. With many of our science major students quite curious about this major topic, we held a lecture session to learn more about this phenomenon.
On June 26th, 2023, the 59th session of the English Lecture Meeting for Science Major Students was held under the sponsorship of the Academic Society of Faculty of Liberal Arts, inviting Doctor Yoshiichiro Kitamura of the College of Science and Technology to give a lecture with the above title, which was the 8th lecture for this event given by the lecturer.
Before starting his lecture, Dr. Kitamura reminded the audience of the usefulness of English-English dictionaries with the following words: “According to my English-English dictionary, the word behavior means “the things that a person or animal does.” If you understand how the meaning of a word is defined in English, you can use the definition to precisely explain the meaning of the word as I do in this presentation. In the future, when you get a chance to teach in a class in English as I do today, or when you talk in international conferences or meetings, an English-English dictionary will greatly help you with communicating with others efficiently. So, I recommend that you find one for you and learn to use it.”
When he was studying digestion of dogs, a Russian physiologist Ivan Pavlov found that the dogs began to salivate whenever his assistants entered the room. Most significantly, Pavlov observed that the dogs would often salivate only at the sight of the assistants even in the absence of food and smell. This occurrence led to the discovery of what is called classical conditioning, one of the most important discoveries in the history of psychology. Since this historic discovery, we have all been familiar with various phenomena called conditioned response.
Dr. Kitamura is a researcher on the process of neurotransmission(神経伝達) in the field of physics and has been engaged in the research on classical conditioning for many years. In this lecture, Dr. Kitamura introduced to the audience consisting of mainly the first-year students of the department of science and technology some of the main topics of classical conditioning by way of answering the following questions: i) what it was exactly that Ivan Pavlov discovered with his canine subjects; ii) what other cases of conditioned response we can observe than just the response to food are; iii) whether other animals or organisms than the relatively higher animals like dogs can learn things in the process of conditioned response; iv) what the properties are that qualify something as a conditioned stimulus, or many other interesting topics.
The audience were greatly amazed at, as well as interested in, the following facts reported by Doctor Kitamura: even the organisms without brains can show conditioned response as long as they can synthesize new proteins; the experiments conducted by the lecturer using earthworms as the subjects, attested that while ‘vibration’ was a conditioned stimulus for earthworms, ‘light’ was an unconditioned stimulus for them, suggesting that seeing light implies death for this species, but feeling vibration (typically from earthquakes) does not necessarily do so; and so forth.
In the subsequent Q and A period, Dr. Kitamura gave detailed answers to all of the six questions asked by the audience including the following two:

Questions and Answers
Q. My question is “How does the brain work when classical conditioning occurs; especially, what changes will occur in the brain, if any?
私の質問は古典的条件づけが起こる時、脳はどのように働いているかということです。もしあるとすればどのような変化が脳内でおきるのでしょうか？
A. As you have learned, in the case of classical conditioning with dogs, the dogs did not respond to the sound of a bell before conditioning, but they learned to respond to it after conditioning. So, the dogs had associated the sound of the bell with presentation of food in this case; in other words, they had actually connected two independent sensory inputs in the brain in such a way that the information in the auditory pathway and that in the taste pathway were neurally linked to each other, with the result that the former activated the latter, thereby inducing dogs to salivate. Because this question needs more explanation, I’ll talk more in detail about it in the following Japanese session today.

Q. Is it possible to combine several conditioned responses making them occur at the same time or in chain reaction? For example, is it possible to stimulate a dog to eat food as a conditioned response and make it want to go for a walk as a consequence of eating food, where the dog is expected to associate the presentation of food with the need to go for a walk?
いくつかの条件反射を組み合わせ同時にあるいは連鎖反応で起こるようにすることは可能か。例えば、犬にえさを与える刺激をして、えさを食べることによってそれが刺激となって散歩に行くことに関連付けることは可能か。ここで、犬においては食物の提供と散歩の必要性が関連づけられている状態が期待されている。
A. I think yours is a difficult question. As you know, dogs usually like walking with their owner very much; in fact, dogs look very happy when they know they are going for a walk. Therefore, we could possibly use “the act of going for a walk” as an unconditioned stimulus for the dogs on a par with presentation of food, which, however, is my personal expectation.
Incidentally, we can condition dogs using an unconditioned stimulus, i.e., presentation of food, on the one hand, and two conditioned stimuli such as the sound of bells and light stimulus, on the other; that is, in this particular case of classical conditioning, a single US and double CSs are associated with each other in a combinatory fashion, thereby inducing a conditioned response of dogs’ salivation. Dogs first learn to associate the sound of a bell with presentation of food, and then they learn to associate the light stimulation with the sound of a bell. In this mode of conditioning, dogs are conditioned in the process of a chain reaction. As expected, dogs finally salivate in reaction to the light stimulation. Processes like this are called “second order conditioning” or “higher order conditioning”.

Wikipediaより

http://www.ldoceonline.com/
http://oald8.oxfordlearnersdictionaries.com/