Beta Rhythm (Music of the Mind)

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 ...

The previous blogs have gotten into how synaptic vessicles fuse with the synapse membrane. Similar mechanisms are used by viruses to enter healthy cells, and are now being harnessed for the latest genetic medical treatments: Gene Therapy and RNA Interference. Some very cool stuff happening in this area. Research into the HIV virus led to some of the first breakthroughs in understanding the membrane fusion mechanism. Retroviruses are particularly adept at invading a wide variety of different human cells, which makes them good models to study for gene therapy. Lifecycle of the virus provides a good intro to how viruses work. The HIV virus anchors itself to a special protein (CD4) on the surface of the helper T cell. This causes the viral membrane to fuse with the host cell's membrane. It's called a Lentivirus (Lenti is latin for "slow"). From the University of Birmingham: HIV as a Lentiviral Vector in Gene Therapy From Kenyon College's web site : What is gene thera...

Previous blog entries have covered what Neurotransmitters are , and how synaptic receptors use these molecules as triggers for complex actions once they have crossed the synapse. This blog entry explores the other side of the synaptic cleft, where the neurotransmitters are stored and released. Nature has developed some amazing machinery to make synapses fire quickly. Relying on the cell nucleus to generate the molecules that act as neurotransmitters when they are needed would be far too slow to achieve the kind of speed required to power thought. Instead, these molecules are made ahead of time, before they are needed, and are kept bottled up in spherical containers called 'vesicles', waiting for the instant that they need to be released. The picture that is evolving on how synapses actually manage this feat is quite fascinating. And, once again, that super cool molecule called 'clathrin' plays a major role... From http://www.hhmi.org/research/investigators/sudho...