Chronistic Serendipity

Much is made of the importance of serendipity to scientific discovery. Here are some well-known examples:

  • Roentgen’s discovery of x-rays.

    Antenna used by Penzias & Wilson

  • Becquerel’s discovery of radioactivity.
  • Hoffmann’s accidental first trip on LSD.
  • Fleming’s discovery of penicillin.
  • Bell’s discovery of pulsars.
  • Penzias and Wilson’s discovery of cosmic background radiation.

All of these “accidental” findings resulted from trained minds being capable of recognizing something unusual and unexpected as worthy of further study. I argue that all of these breakthroughs would have occurred at some point–these folks simply happened to notice them. There was nothing special about the time when the discovery occurred, except that the technology had been developed that allowed it to happen. Once that technology existed, the discovery was inevitable.

However, I suggest that an important discovery in neuroscience–so important that it led to a Nobel Prize–occurred in large measure because of the time when the research was done. The technology that allowed it did not exist a few decades earlier, and a few decades later the technology had changed to the point that the discovery would not have occurred. I’m talking about Hubel and Wiesel’s discovery of the receptive fields of visual cells in the brain’s cortex.

These neuroscientists found that the simplest visual stimulus that activates cells in our cortex is a line, in a particular place and oriented a particular way. Even Hubel has admitted that the discovery was accidental. Cells in the retina and thalamus were known to respond to spots of light (or dark), so Hubel and Wiesel were shining all sorts of spots in front of their anesthetized cats in a failing effort to make the cortical cells fire. 

The scientists used spots painted on glass slides, which were moved around in a projector and displayed on a projection screen in front of the cat. The cortical cells did not respond to the spots, but when the edge of the glass slide moved through the projector, casting a faint line on the screen, a cell responded.  Hubel and Wiesel realized that cortical cells respond not to dots or spots, but to lines, as a result of this accidental finding.

So what was special about this point in time, the 1950s, that allowed this discovery? It is almost certain that, had they done this work in the 1980s or later, they would not have used a glass slide in a projector. Instead, it is likely that they would have used a computer to generate the spots and move them around on a screen in front of the cat. What’s missing in the scenario? The edge of the glass slide. No glass slide, no edge, no line presented to the cat. Their serendipitous finding that cells respond to lines would not have occurred.

The discovery of the nature of the receptive fields of visual cortical neurons rested on the scientists doing the work not after a particular point in time, but in a particular time window. This is an example of chronistic serendipity. I would love to hear examples of others if someone can identify any. Post them as comments below.

Amusing Facebook Juxtapositions

Facebook uses an algorithm to determine what to display on your newsfeed. It is proprietary, and designed to keep you on the page so that you consume the ads that are thrown at you. Occasionally this algorithm places items next to each other that, while not amusing in their own right, become amusing because of their proximity. Over the past several years I have collected examples of such juxtapositions – many appear here. Please note that an “amusing” juxtaposition does not necessarily mean that either item by itself is “funny” — it simply means that in my opinion their adjacency made me think or smile. 




















Great Meeting!

The Pavlovian Society held its annual meeting in Iowa City, Oct 4-6, 2018. Pres. John Freeman put together an excellent program–fabulous talks spanning the breadth of learning. Here are a few photos:

Thoughts on Grad School Admission

[10/10/2018 – It’s been a while – worth moving to the top of the page.]

[10/20/2012 – I now realize that the students who most need to read this are unlikely to do so because it won’t be on the test.]

Occasionally interactions with students remind me of advice that should be given to everyone who hopes to go to graduate or professional school.  Maybe posting my thoughts here will help someone.

  1. Admission to graduate/medical/law/business/etc school is not a right; nobody is guaranteed admission.
  2. Good grades do not get you admitted.  In fact, other than getting the grad/etc program to look at your application, grades are unimportant.
  3. Good test scores (GRE, MCAT, LSAT…) are also largely unimportant other than getting you a second look.
  4. Re-read points 2 & 3 above.  Go ahead; I’ll wait…
  5. OK – here’s the story on good grades and test scores: if you don’t have them you won’t be considered – if you do have them you will be considered, but not on the basis of the grades or test scores.
  6. You have to provide the admissions committee with something that differentiates you from the other applicants with good grades and test scores.  They will learn why they should admit you via the letters that are written on your behalf.
  7. They will also learn from your letters why they should stop considering you.
  8. Letters are critical.

Consider this in your interactions with professors.  You will need to ask some small number of professors for letters – it would be best if these people thought highly of you.  When I write a letter for a student aiming for grad school, I consider whether this is a student I am comfortable sending to work with a friend.  If the answer is “no” then I cannot write a strong letter.  When I write a letter for a student aiming for med school, I consider whether this is someone I would like to find looking down at me when I regain consciousness in the emergency room.  If the answer is “no” then I cannot write a strong letter.

My letter will address your academic abilities, of course, but it will also address aspects of your character that are not apparent in your transcript:

  • Are you responsible?
  • Are you thoughtful?
  • Are you pleasant?
  • Are you polite?
  • Are you interested in learning or just in getting grades?

These are the things that will matter in grad school.  You have to be able to play nicely with others in order to succeed in science; a 4.o GPA is no assurance of this.  If you want me to write a strong letter for you then do not do any of these things:

  • Make an appointment with me then fail to show up (OK – I understand that stuff happens, so in the event of something unavoidable at least act as if you realize that I was inconvenienced).
  • “Grub” for grades.  Yes – it is certainly fine to ask for clarification if you don’t understand why you missed points on something, but it is not fine to argue that you deserve a point simply because a word in your answer matches a word in a related paragraph in the text.  Meaning derives from the combination of words, not from one word.  And think about it this way: is the additional point that you might get worth alienating the person whom you will ask to write a letter for you?
  • Fail to be polite.  A simple “please” or “thank you” goes a long way.  Your profs are here to help you, of course, and we like to do it.  However, our time is valuable, and meeting you outside of class time or office hours takes us away from other things that we need to do.  Acknowledge this.
  • Turn in papers or assignments late.  You will not get leniency in this regard in the real world: if you miss a grant application deadline, or the deadline for submission of your work to a professional meeting, you have missed it, and will simply have to wait until next time.
  • Be a jerk (’nuff said).

To end on a positive note, let me point out behaviors or characteristics that will lead to a strong positive letter:

  • Express interest and curiosity in the world.
  • Strive for understanding rather than for grades.
  • Read.
  • Treat people with respect.

If you do these things, you will be maximizing the chances that you will gain admission to grad school.

[You might also want to read this or oher thoughts on success organized here – similar but with slightly different emphasis.]

“Engram” – When I’m wrong, I admit it.

For as long as I can remember, when I have introduced students to the concept of the “engram,” or “memory-trace”–the change in the nervous system that encodes a memory–I have told them that the word was coined by Karl Lashley. Lashley spent a career, well over 30 years, searching for the engram, an effort described in one of his later papers, The Search for the Engram (1950), in which he famously concluded (with tongue firmly implanted in cheek) that “learning just is not possible.” Basically, he was unable to find the engram.

I learned at the recent meeting of the Pavlovian Society that I have been wrong for all these years. The term “engram” was coined by Richard Semon, an evolutionary biologist and physiologist. His work is little known, as are most of the other memory-relates words that he coined, but “engram” is still going strong.

Apologies to the many students I have misled.

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