Retrospectacle: A Neuroscience Blog

I’m currently working on a paper regarding learning and memory in honeybees. Actually I’ve been working on it for about 3 years. It got put on the backburner when I entered graduate school, but I finally decided its time to get this thing published. So, why not give you a little preview of the remix?

The paper’s topic is a common and well-studied phenomenon in humans, the serial position effect. In the 1960s, Sperling conducted studies on human sensory storage, demonstrating that people have an extremely accurate memory for visual stimulation although the duration is brief. Essentially, people have a very detailed short term memory, the accuracy of which decays rapidly. For example, consider this list of words:

Hippopotamus
Escalade
Buffer
Photocopy
Membrane
Parrot
Device
Headphones
Notepad
Stop Sign
Glove
Leg
Email
Tupperware
Soda
Needle
Cardboard
Medicine
Car
Tea
Wave
Cheese
Studio

OK, now that you’ve read through the list a couple times, go below the fold (and cover up the list with your hand or some paper. Don’t cheat, or you’ll miss the effect!)


You’re covering the list right?

OK, now, what items from the list can you remember with the best accuracy? Write them down, as many as you can remember. Now that you wrote them, look at the list again. How many did you remember, and did you notice a pattern?

In humans, the serial position effect refers to the tendency for people to remember the first and last items presented in a list. Items presented first (the primacy effect) and last (the recency effect) tend to be remembered with greater frequency than those in the middle, therefore an item’s position in a sequence affects its ability to be recalled. The reasoning behind this has to do with the properties of memory storage: short term storage (STS) and long term storage (LTS). New data must spend some time in STS before it can be encoding permanently in LTS, and the capacity of STS is quite limited while LTS is considered nearly infinite.

When personal telephone numbers became common, the government and companies quickly learned to limit telephone numbers to seven digits. This is due to the fact that studies were showing that the limit of human short term memory was seven items, plus or minus two. When a person begins hearing or seeing a list of items to remember, short term memory is mostly empty and more cognitive resources can be spent memorizing the first items which enter STS. There will exist very little interference for these items to pass from STS to LTS. But as the STS begins to be loaded to capacity (7+/-2) and the items keep on coming, interference begins to inhibit these items from being transfered to LTS. The items at the end are remembered well, since this interference ends and the items have less “competition” for the resources needed to shuttle them into LTS. This data is “fresh in your mind,” so to speak.

This results in a curvilinear representation of recall data, where the percent recalled is greater at the beginning and end.
i-29a93ff9dedea99c1c2652e4a3125298-Serial_position.bmp

So what does this have to do with honeybees? Animal studies have demonstrated the serial position effect in a variety of non-human animals (moneys, rats, and birds). Yet no one had explored it in a invertebrate species, such as honeybees. This naturally comes from the assumption that as honeybees are much more neurologically simpler, complex memory phenomena are beyond their grasp. But consider how honeybees must find nectar and pollen in their environment, and remember it well enough (by the position of the sun) to relay this memory to other members of the hive. They “dance” out the location of the food source, other bees take notice and encode this data, and go directly to the food source. Its quite amazing.

So, as honeybees are able to encode and remember complex positional data, could they also demonstrate the serial position effect? We tested this by capturing a bee (in a matchbox) and placing a small drop of non-toxic red paint on its back to identify it. We then took it to an enclosed experimental apparatus with five targets, each had a drop of sucrose (exact same amount). We placed it on a target (which was considered the first) and forced the choice of the next target by removing its cover one at a time. The sequence it visited the targets was recorded. We then allowed it to fly back to the nest from the apparatus, so it could encode the positional data and store its sucrose. It was only a matter of time before the honeybee returned to the apparatus (which had another drop of sucrose on each target), and then we recorded the sequence which the bee visited the targets. The results (of 25 bees record this way) showed a clear preference for the 1st and 5th targets (first and last) it was trained on. The paper in progress will explore more details of the experimental design (don’t want to give away too much!) but it is exciting that the effect is reproduced in honeybees. This seems to suggest that memory is quite similar across species and that highly organized and complex neurological structures aren’t necessarily required for memory.

Comments

  1. #1 coturnix
    June 26, 2006

    Facinating! I can’t wait to read the finished paper for the details of M&Ms.

  2. #2 Doug
    June 26, 2006

    1 – Good Luck – I think Kandel shared a Nobel prize for similar work with a sea slug, Aplysia.

    “Professor Eric Kandel showed that transmitters of the same type as studied by Arvid Carlsson, via the protein kinases characterized by Paul Greengard, are involved in the most advanced functions of the nervous system such as the ability to form memories.”
    http://nobelprize.org/nobel_prizes/medicine/laureates/2000/presentation-speech.html

    2 – I highly recommend the following article -

    ‘What Birds See’ by TIMOTHY H GOLDSMITH, professor emeritus of molecular, cellular and developmental biology at Yale University
    Scientific American, Jul 2006 Vol 295 Issue 1 p68, 8p

    Goldsmith has performed experiments suggesting that birds and reptiles [tetrachromatic opsins + UV + oils in cones] have vision superior to mammals [dichromatic cones but more rod reliance]. Further, some primates, including humans [trichromatic cones] have regained some loss of this vision.

    This appears to suggest that either genes were lost or, probably more likely, two cones were put to other brain uses [neocortex?] during this period of dinosaur domination.

  3. #3 Eric Irvine
    June 26, 2006

    Very cool findings, look forward to hearing more!

  4. #4 Dan Dright
    June 26, 2006

    UR such a smarty-pants I cant standify it!

    werry kewl schweet-haaat.

  5. #5 Doug
    July 4, 2006

    This may relate to your study –
    Ants on Stilts – 29 JUN – report on Matthias Wittlinger, biologist U-Ulm in Science
    “Not only did the stilted and stumpy ants not make it home, but they also misjudged their distances exactly as the researchers predicted. The ants on stilts went about 5 meters too far before stopping to search for the nest, whereas the stumpy ants stopped about 5 meters too short …”
    http://sciencenow.sciencemag.org/cgi/content/full/2006/629/3

    I have been thinking about the nearly logarithmic spiral [LS] of the cochlea. I wonder if anyone has looked in any animal eyes for the placing of cones or rods. Honeybee compound eyes may be a place to start.
    Weber-Fechner and Stevens [I think] thought that there was some connection in human sensory discrimination particularly for sound and sight with the LS.

    There is a clever LS applet about the Mice Problem at MathWorld. LS from outside to in instead of from inside to out.
    http://mathworld.wolfram.com/MiceProblem.html

  6. #6 Jay
    August 4, 2010

    Communication between honey bees is simply by “dancing”, this is how they give direction and information about flowers’ distance to each other. Amazing animals!