Well… it’s about that time. You know, the end of the semester where you start every project you’ve had the semester to complete. At least that’s what I’m doing. I finally made some headway on my Neuro project during the past few weeks. I’m sleep depriving zebrafish; I had planned to devise a scheme using streams of bubbles that work on some obnoxious structure to generate a regular disturbance (alright it was PZ’s idea). However I finally admitted defeat about the same time I shattered a water heater and realized I had gotten nowhere.

Desperately I went to a local farm supply store to look for what I could only articulate as “a really really slow motor.” (I don’t want to hear any comments about torque or gears… A: I probably won’t understand you and B: at this point in the semester, it might make me weep.) I tottered over to what looked like the motor isle… although they could have been bombs or anchors because I wouldn’t have known the difference. I waited until my confused expression attracted an employee and asked if they had any of those “really really slow motors… to… um… turn a rod in my fish aquarium.” The guy actually looked offended like I asked for adult entertainment products. “We wouldn’t sell any of that here.” He replied stiffly. Fortunately his buddy overheard and offered, “You mean like a rotisserie?”

Brilliant! They tried to sell me a one hundred dollar rotisserie which I declined, but the idea was invaluable. Why didn’t I think of that? I was imagining a Rube Goldberg machine with a lot of hot glue. Anyway I found an old rotisserie motor for $5 and am quite pleased. Also, PZ put together a big black box in which I’ll hang a light on a timer. Not only will these fish be gently stirred but they’ll have the lights going on and off all night.

I would feel bad except I’m not sleeping either.

Today in class we learned about the functioning of olfactory nerves. It was really quite interesting, especially to find out how the olfactory system is organized. Let’s begin in the nasal cavity. Here, present in the mucus layer, are projections of the olfactory receptor cells. Each receptor cell is only capable of binding to one specific type of odorant molecule. These receptor cells travel through the porous bone separating the skull from the nasal cavity, and feed into a specific glomerulus. Glomeruli are located in the olfactory bulb, and have multiple receptors feeding into them. However, each glomerulus receives input from only one receptor type. In the glomerulus, the receptor neurons make excitatory connections with other cells, whose own axons project into the olfactory cortex in the brain. What is cool here is that there are about 1000 different types of olfactory receptor neurons, which each have their own proteins. This means that there are most likely 1000-2000 genes encoding for olfaction. It has been shown that this is not a combinatorial system like that developed for immunity.

Another cool thing I learned was that every time someone blows their nose, they are losing part of their brain. Seriously though, it’s not quite as bad as it sounds. What is really happening is that you are losing the olfactory receptor cells that protrude out into the mucus layer inside the nasal cavity. The neat thing is that these cells are able to regenerate, which is unusual for other human neural cells. I was wondering, if perhaps, due to the organization of the olfactory nerves, regeneration is able to happen because of the interaction between the olfactory receptor neurons and the glomeruli. Perhaps the protruding parts of the cells are able to be regenerated because they are actually only part of the cell, not the entire cell. If this is true, then if the glomerulus were destroyed, would that permanently destroy the sense of smell? Or would the glomerulus be capable of regeneration, like the olfactory receptor cells that feed into it?

T. Ryan Gregory has announced that you can now read the inaugural issue of Evolution: Education and Outreach, which includes his own article.

This is the new journal set up by Niles and Gregory Eldredge (father and son) to “provide direct linkage between the worlds of scientific
research and the K-16 classroom.” It is definitely one every science teacher should be watching.

Hey, look here: we have an ad in The Chronicle of Higher Education:

Position: Tenure-Track Position in Biology

Institution: University of Minnesota at Morris
Location: Minnesota
Date posted: 11/19/2007

Biology: The University of Minnesota, Morris seeks to fill a tenure-track position in vertebrate biology beginning August 18, 2008. Duties include: teaching undergraduate vertebrate systematics or natural history and sophomore level human physiology; curating and maintaining the discipline’s vertebrate collection; contributing to the university’s general education program; advising undergraduates; conducting research that could involve undergraduates; and sharing in service activities. Minimum qualifications: Ph.D. in zoology or a closely related field and two years experience teaching undergraduates (graduate TA experience acceptable). Send letter of application, resume, transcripts, teaching and research statements, and three letters of reference to: Biology Search Committee Chair, Division of Science and Math, University of Minnesota, Morris, Minnesota 56267-2128. Applications will be accepted until the position is filled. Screening begins January 7, 2008. The University of Minnesota is an equal opportunity educator and employer.

Today I’m looking at synaesthesia, but more specifically lexical-gustatory synaesthesia in which certain phonemes (smallest unit of speech such as the /l/ sound in jelly) trigger specific tastes. For example, in Jamie Ward and Julia Simner’s (2003) report, Lexical-gustatory synaesthesia: linguistic and conceptual factors, a case study was done on a forty year old business man who reported tasting specific tastes in response to certain phonemes. In this case the man reported tasting cake when the phoneme /k/ was used in a word. Synaesthesia is thought to occur due to the crossing over or connection of neurons in certain areas of the brain that regulate and process senses. However, there are differing theories as to how this arises.

One idea is that certain neural connections linking sensory areas are not destroyed in infant stages of development as done in normal development. Synesthetes therefore link one sensation with another because connections are not destroyed. The second theory is that, rather than sensory areas in the brain being directly connected, they are connected through neural pathways in higher processing areas. For instance, instead of just hearing a phoneme and having just any taste sensation, it is the processing of the sequences of phoneme in the word used that links to specific learned schemas connected to the phonemes leading then toward a specific taste. Ward and Simner examined this in their case study.

Through documentation of tastes stimulated by specific words and phoneme triggers, Ward and Simner found that their data supported the latter of the two theories. The largest support comes from the idea that the subject’s tastes are specific for certain learned phoneme association rather than just random association of tastes to arbitrary phonemes. For example, as stated earlier, certain phonemes consistently trigger specific tastes such as the phoneme /k/ and the taste of cake. Also, the use of semantics in the sensory process is a strong argument for higher processing connections as food names exhibit their tastes (cabbage triggers the taste of cabbage). Much of this may be because certain patterns of phonemes can trigger specific tastes that have the same sequence of phonemes. So college, having the phoneme sequence /edg/ triggers the taste of sausage which also contains the phoneme sequence /edg/. These associations are done through higher processing which is learned throughout life, supporting a connection through higher processing areas of the brain rather than direct connection between sensory areas.

Although the idea of a direct connection between sensory areas from birth is not disproved by the study, it has supported that there is higher processing connections involved that have developed through learning. There is still much work in the field of synaesthesia, and with any luck, it will lead us to a better understanding of how our brains develop and process information. But despite all this, the best thing to do right now if you are not a lexical-gustatory synesthete is eat leftover turkey, potatoes (cheesy or mashed), and some pumpkin pie. Happy holidays.
~Bright Lights

I was happily absorbed in my slightly vegetative stupor on the couch when my roommate walked into the room and starting talking about physics. Ugh, physics, I thought, but I politely listened as she began talking about lenses, specifically how they are related to sight. It is common knowledge that the images we see are inverted on the retina, and then further processed. However, my roommate was discussing experiments done on humans that inverted their vision by 180 degrees and found that, though at first they could not function normally, eventually they adapted. I thought this was fascinating, and wondered what the brain had to do with this process. Unfortunately my roommate’s knowledge was pretty limited, so I decided to do some research of my own.

Research on visual distortion of the retina has been going on for quite some time. Devices have been used that invert the retinal image, so that everything is seen upside down. At first subjects wearing this device will reach for things and miss, or will bump into things as they travel about a space. Eventually, they adapt. What I wanted to know is how do they adapt? What changes take place in the brain that allow them to do so? Is it just simply learning to reach a little farther to grab something, or walk a bit differently to avoid bumping into something? What is happening at the neural level?

[Read more…]

The good Lynch of Stranger Fruit was honored as the CASE/Carnegie Professor of the Year awardee for Arizona. Everyone go applaud!

This week I’ve been diving in a little more into doing some actual research myself. Nothing breakthrough mind you, just some simple experiment to sort of understand the world around and inside of me a little better. My partner and I are looking into how the optic nerve develops inside of zebra fish and how its development may be affected by developing the fish in total darkness. We are trying to stain 1-2 day old zebra fish with Dye-I by simply poking the dye into the retina with any sort of small sharp object we can find. We’ll then separate the groups of stained fish into those that develop in a small flask with normal exposure to light (about 10-15 hours a day of UV light) and those that develop in a tin-foil-wrapped flask with no UV exposure in which feeding will be done under red light.

Every few days, I hope to take some of the fish out and look at how their brains are developing using a fluorescent microscope that allows me to see how the dye is traveling. With any luck, I’ll see a decently clear pattern of paths of nerves from the retina to the lateral geniculate. I’m not sure where it leads from there as the zebra fish has mainly the midbrain rather than our large forebrain with a thalamus and cerebral cortex. More research on my fish is definitely needed before I can do any real analyzing of the staining technique, but my real problem right now is just getting some fish stained!

Using a pin head dipped in dye, I had been trying to poke the retinas of these fish. Once the retina ruptures, almost any amount of dye should stain the retina and lead to further staining of the optic nerve as development continues (from what I’ve read, usually the rods and cones develop about 4 days at the earliest). I ran into many problems with this of course and have been fishing (oh so hilarious, I know) for new solutions ever since.

The first problem I had is that the head of the pin is about the size of the fish’s eye itself, so trying to rupture the eye with it is like trying to shove a baseball bat through my own. Of course actually rupturing the retina with this gigantic tool will only happen if my mounted fish would stop moving every time I get close to it, which is the second problem. So far, I’ve created new tools by heating TLC spotters over a flame in the organic chemistry lab and then pulling it in half so that the glass is pulled into a tiny pipette with a head just smaller than the fish’s retina. This has been successful after coupling it with a technique for knocking out my fish to keep them still. I burst a small bubble of anesthetic (0.5 MESAB) over the water that I’m using to mount my fish before injecting the fish in augar onto the slide. This does a great job in keeping the fish still so I can do my dirty work of staining its eye, but sometimes the concentration of anesthetic is too strong and the fish will die. All in all, with much more research and some patience this may turn out to be a fun little project. If you have any ideas as to where I should be looking for research and anything else I could be doing with this experiment, let me know.
~Bright Lights