Beta Rhythm (Music of the Mind)

If there was one experience that pushed my interest in neurobiology beyond the activation threshold and kick-started the process that led to the creation of this blog, it was reading Dr. R. Douglas Fields' article "Making Memories Stick" in the Feb. 2005 issue of Scientific American ( ref. ). I'd long been interested in molecular biology but had been intimidated by the level of jargon and assumed knowledge that filled most articles. Dr. Fields' article explained the inner workings of a neuron so clearly and lucidly that I was able to get a basic understanding of what was happening, and was motivated to try to learn more about molecular biology and neurobiology in particular. This blog is essentially the notes I've been making as I try to learn more about the details of how biology works at a molecular, cellular and neuronal level. So, things have finally come full circle. Let's take a deeper look at what makes memories stick... From Making Memories Sti...

I happened to stumble upon Martin Rodbell's 1994 Nobel Lecture paper : "Signal Transduction: Evolution of an Idea" again recently. I really enjoy reading these Lecture papers as they are a) written by the scientists that did the breakthrough research, b) contain a lot of insights into the creative process behind their discoveries and c) are intended for a general audience. Rodbell's paper is a good example. The following excerpt from his lecture paper bridges two areas I had no idea were related: G-protein receptors and the cytoskeleton. (The picture at right is from the web page for Andres Lebensohn of the Kirschner Lab at Harvard. It shows the assembly of an actin network.) G-PROTEINS ARE SIMILAR IN STRUCTURE AND REGULATION TO CYTOSKELETAL PROTEINS. by Martin Rodbell During these studies, my attention was drawn to the striking similarities in the properties of G-proteins with those of tubulin and actin, the major cytoskeletal elements in cells. For example, G...

Overview From Sandra Ackerman's book Discovering the Brain : The actual signals transmitted throughout the brain come in two forms, electrical and chemical. The two forms are interdependent and meet at the synapse, where chemical substances can alter the electrical conditions within and outside the cell membrane. A nerve cell at rest holds a slight negative charge (about –70 millivolts, or thousandths of a volt, mV) with respect to the exterior; the cell membrane is said to be polarized. The negative charge, the resting potential of the membrane, arises from a very slight excess of negatively charged molecules inside the cell. A membrane at rest is more or less impermeable to positively charged sodium ions (Na + ), but when stimulated it is transiently open to their passage. The Na + ions thus flow in, attracted by the negative charge inside, and the membrane temporarily reverses its polarity, with a higher positive charge inside than out. This stage lasts less than a millisecond,...

Previous posts have covered a number of the low-level building blocks that are used by cells in the brain - things like ion channels, neurotransmitters, receptors, clathrin, vesicles, etc. This post focuses on some important pieces of infrastructure that are needed to enable the brain to do its thing.  Neurons operate in an aqueous medium - a kind of salt water bath, water that is full of postively charged ions (cations like sodium, potassium and calcium) and negatively charged ions (anions like chlorine).   Water molecules are V shaped and have a non-uniform distribution of charge - i.e. one end of the water molecule is more positively charged than the other end.  Like charges repel and unlike charges attract.  As a result, a sphere of these 'polar' water molecules tends to surround the ions (a 'sphere of hydration').   Complicating the picture further is the fact that charged particles like ions are influenced by both concentration gradient...

It's tempting to oversimplify things.  Like neurons.  It would be nice if there were one type of neuron, and all you needed to know about how neurons work could be clearly labelled on a diagram of that one type of neuron.  Well, nature LOVES to specialize.  So, before getting deeper into how neurons work, I thought it would be good to take a step back and get some vocabulary in place...   The Basics From University of Washington's 'Neuroscience for kids':   Neurons come in many different shapes and sizes. Some of the smallest neurons have cell bodies that are only 4 microns wide. Some of the biggest neurons have cell bodies that are 100 microns wide.  Neurons are similar to other cells in the body because: Neurons are surrounded by a cell membrane. Neurons have a nucleus that contains genes. Neurons contain cytoplasm, mitochondria and other "organelles" . Neurons carry out basic cellular processes such as protein synth...

 One of the most powerful ways to find out what a gene does is to disable the gene in a seed, an ova or an embryo, grow the resulting 'transgenic' organism and find out what functions are missing.  This approach is being done for mustard seed and mice in order  to identify the function of each gene in these 'model organisms'.   Since many genes are re-used in other organisms, it is hoped that determining the function of each of the 29,500 mustard seed genes will shed insight into the genetics of other plants, and that determining the function of the murine genes in transgenic mice will translate into knowledge of the genetics of other mammals, like humans.   1000s of varieties of mustard From the NSF : To create a gene knockout, scientists use a bacterium called Agrobacterium to insert a code that tells a specific gene to turn off. According to Ecker, this process of T-DNA integration has been carried out for well over 25 years, but ...