diff --git a/2016-09-17-lecture01.md b/2016-09-17-lecture01.md index c82c2a9..d1d5e13 100644 --- a/2016-09-17-lecture01.md +++ b/2016-09-17-lecture01.md @@ -37,9 +37,11 @@ REASON YOU CANNOT ENROLL: ## Site keyboard bindings * Navigate: `arrow keys` and `spacebar` +* Menu: `m` * Fullscreen: `f` * Overview: `o` or `esc` * Zoom object: `alt/option–click` +* Print: `...lecture.html?print-pdf` @@ -146,15 +148,16 @@ sinew
* We are now in a gene-centric “post-genomic” phase of neuroscience -* Human genome sequenced- approximately 20,000 genes. -* Most genes are expressed in the brain, either during development or in the adult. It is the spatial and temporal regulation of these genes that builds a nervous system. -* Mice, flies, and worms have nervous systems and even express many of the same genes as humans. Genetics allows us to correlate gene activity with nervous system function. +* Most genes are expressed in the brain, either during development or in the adult. It is the spatial and temporal regulation of these genes and an organisms interaction with the environment that builds a nervous system. * Neuroscience therefore encompasses many fields, including genetics, cell biology, physiology, and development biology. Note: +- not nature or nurture, nature and nurture +- language, learning to ride a bike +- clones, identical twins --- @@ -180,6 +183,8 @@ Note: Number of genes is not related to nervous system complexity or size. The nematode c. elegans has just 302 neurons, and yet its genome contains virtually as many genes as a humans. An african elephant brain weighs 3 times more than a human brain and has 3 times the number of neurons. +Even number of base pairs: Paris japonica has 150 billion base pairs of DNA (50x larger than that of a human haploid genome) + The largest brains are those of sperm whales, weighing about 8 kg (18 lb). An elephant's brain weighs just over 5 kg (11 lb), a bottlenose dolphin's 1.5 to 1.7 kg (3.3 to 3.7 lb), whereas a human brain is around 1.3 to 1.5 kg (2.9 to 3.3 lb). Brain size tends to vary according to body size. * Drosophila 7-11 days (28-34degs C) @@ -231,9 +236,15 @@ Note: Now to do neuroscience research we have to use model organisms of course. Small number of neurons, can be labeled using green fluorescent protein or other means. -C. elegans is a nematode or roundworm. It is non-infectious and non-parasitic organism just 1 mm long and it can be easily genetically engineered. That means you can introduce mutations to genes or express fancy inert proteins that allow you to track the function of genes and cells in living animals making it a great model organism. For neuroscientists it has only 302 total neurons making it a great model organism. Many mutant worms have been isolated that affect nervous system function allowing us to learn about the function of those genes. And you can engineer the worms to express fluorescent proteins so that the animal's neurons glow under a microscope. How many of you have heard of green fluorescent protein? +C. elegans is a nematode or roundworm. It is non-infectious and non-parasitic organism just 1 mm long and it can be easily genetically engineered. That means you can introduce mutations to genes or express fancy inert proteins that allow you to track the function of genes and cells in living animals making it a great model organism. -However, we have more than a million neurons that just form the optic nerve from each of our eyes! +For neuroscientists it has only 302 total neurons making it a great way to dissect neural circuits underlying simple behaviors. Many mutant worms have been isolated that affect nervous system function allowing us to learn about the function of those genes. And you can engineer the worms to express fluorescent proteins so that the animal's neurons glow under a microscope. How many of you have heard of green fluorescent protein? + +Having just 302 neurons is great for for some types of studies, however we have more than a million neurons in each of our eyes just alone + + + +More than 1 million neurons that just form the optic nerve from each of our eyes! --- @@ -250,7 +261,12 @@ Squids have unusually large axons (1 mm diameter) Note: -Jules Verne provided inspiration for the space age +Jules Verne provided inspiration for the space age but also neuroscientists in the 1940s. + +Squids are arguably the most important model organism in the history of neuroscience. They are rarely studied anymore but their large axons which are 1mm in diameter-- 1000x bigger than our axons-- made their axons amenable to sticking electrodes inside them in the 1930s-50s and allowed neuroscientist to discover the biophysical and mathematical basis of neuronal signaling. We will discuss squid giant axons in much more detail soon. + +Other important invertebrate organisms in neuroscience research include sea slugs and fruit flies and zebrafish. Some of these are very amenable to genetic engineering like C. elegans and have nervous systems more similar to our own. + Phylum: Mollusca Class: Cephalopoda @@ -266,9 +282,6 @@ Order: Sepiida Family: Sepiidae Genus: Sepia -Squids are arguably the most important model organism in the history of neuroscience. They are rarely studied anymore but their large axons which are 1mm in diameter-- 1000x bigger than our axons-- made their axons amenable to sticking electrodes inside them in the 1930s-50s and allowed neuroscientist to discover the biophysical and mathematical basis of neuronal signaling. We will discuss squid giant axons in much more detail soon. - -Other important invertebrate organisms in neuroscience research include sea slugs and fruit flies and zebrafish. Some of these are very amenable to genetic engineering like C. elegans and have nervous systems more similar to our own. --- @@ -368,7 +381,7 @@ Note: Seems fairly obvious now. But wasn't in the 19th c. Cells widely accepted everywhere else in the 1830’s. But neuroscientists were the last to accept this right up until the turn of the 20th c. -Only after fundamental and rigorous work by these two scientists, C. Golgi and S. Ramon y Cajal in the late 19th c. did we come to appreciate comprised of individual cellular elements rather than a +Only after fundamental and rigorous work by these two scientists, C. Golgi and S. Ramon y Cajal in the late 19th c. did we come to appreciate comprised of individual cellular elements rather than a continous network or syncytium. --- @@ -694,7 +707,7 @@ False color of the dendrite of one neuron near an axon from another neuron from * Neurofilaments, actin microfilaments, and microtubules * Provide structural strength along length of axon * Axonal transport of biochemical substances -* Carry neuronal electrial signals (action potentials) away from the cell body +* Carry neuronal electrical signals (action potentials) away from the cell body