Thinking Fast and Slow about Thirst

Out of all motivational states, thirst should have been a simple one to understand. One feels thirsty when one is dehydrated, which can be detected from blood volume and osmolarity. Drinking water hydrates one’s body and quenches thirst. This is a homeostatic model. Intuitive, right? Well, the strange thing about thirst is that it is quenched within seconds to minutes after drinking water, which is too fast for any changes in the blood to happen. This is as if the brain gets hydrated before the body, which makes little sense since there is no specialized canal that passes water from mouth to brain (thank goodness). On the other hand, the buildup of the thirst drive is usually rather slow, meaning that thirst state can change on both a fast and slow time scale. How does it work?

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Consider the Fun

Scientists are often portrayed in pop-culture as pedantic types, with personalities as stiff as their starched white lab coats. While they may have a pressing work ethic and incessant care for detail, their work is creative by nature. Scientists must create knowledge by designing and building experiments. In this way, a scientist is closer to a starving artist than to an automaton.

A scientific project might be spawned from reading a paper and finding an unanswered question, or just observing a phenomenon and wondering how it happens. This stage is quite exciting – you imagine yourself doing experiments that will answer your question (or you imagine collecting data using some brand-new technique, and the results would be unlike anything anyone’s ever observed). The prospect of discovering something new is as thrilling as falling in love. (more…)

The touch of a fly

Our sense of touch has an innate connection with our emotions. Gentle touches are soothing for not only us but also other animals. For example, classic experiments by psychologist Harry Harlow in the 1950s found that an infant monkey raised with two robots, one providing food and the other wearing soft cloth, spends more time cuddling with the cloth robot1. When scared, the infant monkey also goes to the cloth robot for protection. Clearly, there is a special pathway that guides touch sensation to the depths of animal instincts. Working out this pathway requires knowledge about the neural circuitry processing touch sensation.

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[Throwback Thursday] A gene to unite hot and hot

It is no linguistic coincidence that high temperature and spiciness share the same word in the English dictionary: they induce the same burning sensation. The biological basis for this commonality was discovered in 1997 by David Julius’s group at UCSF1.

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TBT: Responses of Neurons of Primary Visual Cortex of Awake Unrestrained Rats to Visual Stimuli

In my research on the rat visual system, I have been designing an apparatus that would allow me to record neuronal responses to visual stimuli in freely moving rats. Most visual neuroscience experiments are now performed on restrained animals, who are usually treated with different drugs to suppress movement (anesthetics, muscle relaxants). But as anyone who has tried reading while falling asleep knows, just because your eyes are open does not mean that information is getting through to the brain. It makes more sense to study how neurons respond to images when the research subject is awake and paying attention.

While few researchers are studying vision in unrestrained rats today, I was surprised to find that the basic setup I have been working on for my experiments had already been created — in 1980’s Soviet Russia.

Working at the Moscow State University, Sergei Girman wanted to study the visual system in freely moving animals. So Girman chose to perform his experiments on rats, noting two features that made them convenient to use –  “the eyes in this animal are relatively immobile,” making it easy to know where they are looking (researchers go through a lot of trouble training a monkey to look at computer monitors in visual experiments), “while the visual analyzer is well developed” (analyzer being perhaps the fashionable word of the time to refer, in this case, to the visual areas of the brain).

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