Lobsters, Axons, Telephones, and Extracellular Recordings – A look at how neuronal signals can be transmitted differently under certain pharmacological conditions.
Neuronal signals are normally transmitted from cell bodies, or somas, to terminals via extensions called axons. At these terminals, connections called synapses are made with other neurons whereby the signals are released via the aide of chemical messengers called neurotransmitters. Many still believe that axons are reliable conductors of these signals.
However, with several years’ worth of experiments, scientists have questioned the fidelity of axonal conduction. They’ve realized that axons do not work like telephones. While telephones and axons may both have buttons – at the terminals in axons – only telephones faithfully conduct signals. And only telephones ring aloud and send messages to voicemail…
In any case, neuronal signals, unlike telephone signals, can change along their paths. Moreover, the pre-synaptic neuron may communicate a different message from the one originally sent from the soma to the synapse with the post-synaptic cell. Researchers at the lab I’ve been working at this summer, the Whitney Laboratory for Marine Bioscience, have focused on the role of neuromodulation in signal transmission along axons, particularly by the well-known neurotransmitter – dopamine. More
You’re lying on a sandy beach on a hot sunny afternoon, enjoying a few hours of much needed laziness. As you open your eyes and confront the vastness of the ocean in front of you, light of 600nm wavelength hits your retina, kindling an impossibly long cascade of events in your brain: a molecule called retinal changes shape, neurons fire action potentials down the optic nerve, arrive at the lateral geniculate nucleus deep in the brain causing more action potentials in primary visual cortex in the back of your head, and so on ad infinitum. At some point, the mechanical wonder of 100 billion neurons working together produces something special: your experience of the color blue. What’s special is not that you can discriminate that color from others; nor that you are aware of it and paying attention to it. It is not notable that you can tell us about it, or assign a name to it. It’s that you have a subjective, qualitative experience of the color; there is something it is like to experience the color blue. Some philosophers call these experiences qualia – meaning “what kind” – but it is not important what kind of experience you are having, just that you are having one at all. Modern science hypothesizes that subjective experience is a product of the brain, but has no explanation for it. More
Dolphins are pretty amazing creatures, to put it simply. In Douglas Adams’ The Hitchhiker’s Guide to the Galaxy, the dolphins knew of the Earth’s impending doom well before people did (“So long, and thanks for all the fish!”). In addition to their extraordinary cognitive abilities, they have highly developed and extremely interesting social skills (such as killing for pleasure).
Speaking of killing, let’s discuss sharks. Contrary to popular belief, sharks are only dangerous if you give them reason to be. During the course of my summer internship, I’ve seen many sharks, from toothless dogfish to five foot long juvenile tiger sharks. All have been docile; they tend not to try to attack unless you poke them hard enough (in an out of water case). But, say you happened to be standing in front of the aforementioned tiger shark’s mouth and poked it, and it flailed and bit your leg. You’d probably scream in pain, bleed, and need to see a doctor right away.
Now consider an in water encounter between a dolphin and a shark. The dolphin could just be swimming normally and pass a shark. The shark could misinterpret the dolphin swimming nearby as a threat, and attack, leaving a 3 centimeter deep, 30 centimeter long, 10 centimeter wide wound. Not only would the dolphin not feel pain from this, but it would continue feeding, swimming, and behaving normally! Even more amazingly, the wound would heal over time with little scarring or changes in overall contour! More
Going on vacation with my family for thirteen days was both exciting and daunting. The West Coast adventure was extremely appealing and I couldn’t wait to see the Grand Canyon, explore Yosemite National Park, and drive a convertible down the Pacific Coast Highway. But where was I going to get my brain fix? The Scientific American issue I bought for the flight to Phoenix wasn’t doing it for me. Some hope was gained at The Exploratorium, a hands-on science museum in San Francisco that managed to convince my thirteen-year-old sister that neuroscience might be almost potentially cool, but it wasn’t until a trip to Sonoma County that my curiosity was finally piqued.
Tiger the horse and I were riding along on a vineyard tour and I was talking to the tour guide about school. I’ve got yet another new response to “I’m studying neuroscience”: the tour guide told me about his son’s mysterious mental illness that may or may not be schizophrenia and we rode through wine country discussing psychiatrists, Thorazine, thought disorders and SSRIs. All in all, a good day.
This conversation got me wondering about the kinds of challenges psychologists and psychiatrists face when having to diagnose patients with schizophrenia. All the clinicians have to go on are whatever behavioral abnormalities make themselves apparent. But how do you weed out schizophrenia from other kinds of psychosis (some of which may respond to the typical treatment for schizophrenia)? More