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neuroanatomy1.md
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@@ -4,7 +4,7 @@ Neuroscience is a field of scientific study that seeks to understand how the ner
<img src="figs/human-brain.svg" height="300px">
https://canvas.ucsc.edu/courses/36780
https://canvas.ucsc.edu/courses/46898
<div style="font-size:0.5em;">
<!-- date: -->
@@ -12,6 +12,8 @@ https://canvas.ucsc.edu/courses/36780
Note:
[video of microetching 'self-reflection' project](https://player.vimeo.com/video/216052850) and info on [how it was made](http://www.gregadunn.com/self-reflected/how-self-reflected-was-made/) by G. Dunn and B. Edwards
Welcome. This class will be an Introduction to Neuroscience–
Neuroscience is a field that by necessity integrates information and techniques from many other scientific disciplines— not just biological sciences like genetics, molecular biology, biochemistry, immunology, physiology. But also physics, engineering, computer science, psychology. And these days neuroscience is touching upon fields as varied as sociology, criminology, marketing, ethics, and the law. So what is Neuroscience? Neuroscience is fundamentally a field that...
@@ -26,7 +28,7 @@ And ultimately it is a field of science that seeks to understand how this lump o
## Syllabus and text book
<div><a href="https://canvas.ucsc.edu/courses/36780/assignments/syllabus">https://canvas.ucsc.edu/courses/16047/assignments/syllabus</a></div>
<div><a href="https://canvas.ucsc.edu/courses/46898/assignments/syllabus">https://canvas.ucsc.edu/courses/46898/assignments/syllabus</a></div>
<div style="width:200px;"><img src="figs/ScreenShot2016-01-04at3.59.29PM_dea1077.png" height="200px"><figcaption>5e 2011</figcaption></div>
@@ -40,17 +42,19 @@ And ultimately it is a field of science that seeks to understand how this lump o
<div></div>
* Navigate: arrow keys and `spacebar`
* Menu: `m`
* Overview toggle: `o` or `esc`
* Fullscreen: `f`
* Overview: `o` or `esc`
* Notes: `s`
* Zoom: `alt-click` or two-finger multi-touch (touch screens/trackpads)
* Zoom-scroll: two-finger drag (touch screens/trackpads while zoomed in)
* Show notes: `s`
* Search toggle: `ctrl-shift-f`
* Menu toggle: `m`
* List keyboard shortcuts: `?`
<!-- * Zoom: `alt-click` or two-finger multi-touch (touch screens/trackpads) -->
<!-- * Zoom-scroll two-finger drag (touch screens/trackpads while zoomed in) -->
<!-- * Print: `...neuroanatomy1.html?print-pdf` -->
Recommend browser is Firefox or Chromium on a laptop/PC. Some features that only have keyboard bindings (e.g. fullscreen, overview) may not work or be disabled on tablet/touch screen devices.
<!-- Recommend browser is Firefox or Chromium on a laptop/PC with a keyboard. Some features that only have kbd bindings (e.g. fullscreen, overview, notes) may not work or be disabled on tablet/touch screen devices. -->
</div>
@@ -58,14 +62,21 @@ Recommend browser is Firefox or Chromium on a laptop/PC. Some features that only
## What are the nervous system’s functions?
* The nervous system organizes and controls an individual’s appropriate interactions with the environment <!-- .element: class="fragment fade-in" data-fragment-index="1"-->
* Its functions are dynamic, vast and wide-ranging – extending to include all thoughts, perceptions, bodily actions, behaviors, and even the very essence of one’s being: consciousness and the mind <!-- .element: class="fragment fade-in" data-fragment-index="2"-->
* The nervous system organizes an individual’s interactions with the environment <!-- .element: class="fragment fade-in" data-fragment-index="1"-->
* Its functions are dynamic and wide-ranging– extending to include all actions, thoughts, perceptions of the self. <!-- .element: class="fragment fade-in" data-fragment-index="2"-->
<div style="font-size:1.5em">
<div></div>
Navigation. <!-- .element: class="fragment fade-in" data-fragment-index="3"-->
</div>
Note:
What does the nervous system do? It organizes and controls an individuals interactions with the environment. It does this by processing current or past experiential information and making and executing behavioral decisions.
Therefore the brain’s functions are dynamic, vast and wide ranging, and extends to include all thoughts, perceptions, and actions and the very core of what it means for each of one us to be us–– consciousness and the mind. It is this complex lump of biological tissue, this emergent computational system that allows us humans to not only imagine the future, but to create it as well.
Therefore the brain’s functions are dynamic and vast, extending to include all thoughts, perceptions, and actions and the core of what it means for each of one us to be us–– consciousness and the mind. It is this complex lump of biological tissue, this emergent computational system that allows us humans to not only imagine the future, but to create it as well.
--
@@ -96,38 +107,38 @@ Ever since the dawn of the industrial age in the mid 19th century and Jules Vern
The human brain and its limitless creativity has packed a bunch of computational power into this little device in our pocket. And yet this device is really just made up of lots of simple little semiconductive elements. So what is the atomic unit of our brains function and how is it structured to achieve our cognitive abilities and our consciousness? We will find the answers to some of these question in this course, but will also discover as is usually the case when looking into nature's secrets that we humbly know so little.
Or perhaps a discomforting future where maybe consciousness will be woven into some sort of singular virtual world like in the matrix or the cylons from Battlestar Galactica in ten or ten thousand years?
Or perhaps a discomforting future where maybe consciousness will be woven into some sort of singular virtual world like in the matrix or the cylons from Battlestar Galactica in ten or ten thousand years? Oh shoot wait, the metaverse is already here in 2021.
Think of virtual reality which is now almost a reality, can we solve the mismatches between sensory information and body positioning to get rid of the nausea associated with this technology? Think of artifical intelligence and robotics
Think of virtual reality, can we solve the mismatches between sensory information and body positioning to get rid of the nausea associated with VR technology? Think of artifical intelligence and robotics
If we will be traveling through space (well technically we are already traveling through space;) we will need to keep our bodies disease free to get wherever we are going-- will we know enough about brain function and neurolgical disease to fix things on the fly with a medical tricorder device like in Star Trek?
Traveling through space (well technically we are already traveling through space together on spaceship earth;) we will need to keep our bodies in working order to get wherever we are going-- will we know enough about brain function and neurolgical disease to fix things on the fly with a medical tricorder device like in Star Trek?
Can we read the minds of a suspect in a courtroom with a brain imaging device? Do we even want to do that?
Can we read or even predict the minds of a suspect in a courtroom with a brain imaging device? *Should we even want to do that?*
Since that time we've dreamed up fantastical futures in shows like Star Trek and the Jetsons and dystopian ones in Blade Runner and the Terminator or even ones past (for example think "long time ago in a galaxy far far away...")
We've dreamed up fantastical futures in shows like Star Trek and the Jetsons and dystopian ones in Blade Runner and the Terminator or even ones from the past (e.g "A long time ago in a galaxy far far away...")
Some of the **things** dreamed of are already present. Flying aeroplanes, personal landspeeders, rocket ships to distant planets, autonomous-automobiles.
Some of the **things** dreamed of are or will soon be present. Flying aeroplanes, personal landspeeders, rocket ships to distant planets, autonomous-automobiles.
- Edgar Rice Burroughs A Priestess of Mars: John Carter hurling thought waves.
- Do Androids Dream of Electric Sheep: Penfield mood organ
- Do Androids Dream of Electric Sheep: Penfield mood organ (W. Penfield was an prominent canadian neuroscientist)
* So is the nervous system then a device for
- detecting physiological change?
- seeking pleasurable rewards? a dopamine machine?
- navigating space + time?
- processing emotional secretions?
- navigating space-time?
---
## Questions to keep in *mind* as we study neuroscience now and beyond
* What signals are produced by a nervous system? How? Why?
* How are input stimuli from the external or internal environment transduced by the nervous system?
* Where and how does sensor input get tranformed into a behavioral decision and an output pattern to be actuated?
* What is a structure? What is a function?
* What signals are produced by a nervous system? How?
* How are inputs from the external or internal environment transduced by the nervous system?
* How do sensor inputs combine with a self's existing world model to allow decisions and an output to be actuated?
* Structure? Function?
Note:
@@ -161,17 +172,63 @@ A glob of squishy jello? <!-- .element: class="fragment strike" data-fragment-in
<figure class="fragment fade-in" data-fragment-index="1"><img src="figs/image11_fbb6fc7.png" height="100px"><figcaption>Wikimedia Commons</figcaption></figure>
Cells. (though jello is made of collagen...) <!-- .element: class="fragment fade-in" data-fragment-index="1"-->
Interacting sets of protoplasmic colloidal containers. Cells. <!-- .element: class="fragment fade-in" data-fragment-index="1"-->
Note:
So what are brains made of? Anybody? Jello? What is this 1.5 kg or 3 lb human brain made of?
Yes it is soft and squishy but it is not just a gelanitous mass like jello. Shown here is a section through a human brain. It is about 20 cm long and if we were to zoom in on a tiny part of it and use a special dye and microscope what we see is that the brain is made of cells. So this is a pyramidal neuron in from the cerebral cortex and its cell body is about 30-40µm in diameter.
Yes it is soft and squishy but it is not just a gelanitous mass like jello. Thought jello is lots of collagen, and we are lots of collagen, including whaterver a brain is. Shown here is a section through a human brain. It is about 20 cm long and if we were to zoom in on a tiny part of it and use a special dye and microscope what we see is that the brain is made of cells. So this is a pyramidal neuron in from the cerebral cortex and its cell body is about 30-40µm in diameter.
(though jello is made of collagen...)
colloid (wn, noun)
: (a mixture with properties between those of a solution and fine suspension)
protoplasm (wn, noun)
: (the substance of a living cell (including cytoplasm and nucleus))
--
## Elemental entities
<figure><img src="figs/periodic-table-elements-sprial.svg" width="400px"><figcaption>
O. Benfey's 1964 table, [commons.wikimedia.org](https://commons.wikimedia.org/wiki/User:DePiep) CC BY-SA 3.0
</figcaption>
Note:
Based on Otto Theodor Benfey's spiral periodic table from 1964:
<https://en.wikipedia.org/wiki/Periodic_table#/media/File:Elementspiral_(polyatomic).svg>
--
## Sizes of some different entities
object | diameter (millimeters)
--- | ---
dot, sand grain, paramecium | 1.0
animal cell, muscle, bone, brain cells | 0.01
bacteria, mitochondria, chloroplast | 0.001
virus (influenza) | 0.0001
protein | 0.000001
water molecule | 0.000000275
Note:
Radius for sphere model protein:
- Rmin 1 <--> 5 nm
- Size 5 <--> 500kDa
* 1 angstrom = 0.1 nm
* 2.75 angstroms = 0.275 nm == H2O diameter
---
## Brains are made of cells
## Brains consist of interconnected cells
* Camillo Golgi (Italy)– believed that cells in the brain were directly connected forming a **continuous network** (reticular theory).
* Santiago Ramon y Cajal (Spain)– Brains made up of single cells and communicate at specialized areas called synapses.
@@ -224,8 +281,9 @@ Syncytiums are important in living organisms. From the placenta at the beginning
## The Neuron Doctrine
* Santiago Ramon y Cajal
* Neurons are cells. Each is an *individual entity* anatomically, embryologically, and functionally.
* Neurons have a functional polarity
* Neurons are cells. Each is an *individual entity* from an anatomic and embryologic view
- *Function, however, involves the connection across spacetime between multiple entities*
* Neurons have a polarity
<figure><img src="figs/cajal_retina_bff166d.jpg" height="300px"><figcaption>Cajal drawing of golgi stained retina. Cells are separate units and arrows indicate direction of information flow.</figcaption></figure>
@@ -283,10 +341,26 @@ Note:
- in cerebral cortex humans generally have most neurons, where we have about 20 billion. Even compared to an elephant that has 3 times the number of overall neurons. Though some species of cetaceans (whales and dolphins) approach the number of our cortical neurons and recent research has shown that the long-finned pilot whale likely has more neurons in its cerebral cortex than we do.
100 billion sands grains could fit in a dump truck (~ 5 meters long).
```python
d=1 #unit diam of sand grain as perfect sphere
#sphere fits in perfect cube with side length equal to d. Let d=1mm, then:
100e9 ** (1/3)
#so 4641 mm side cube or 4.6 m cube filled with uniformm 1 mm particles
4641**3
```
A billion hours ago our ancestors were living in the stone age
A billion days ago no one walked on earth
---
## The nervous system and its function is the product of both our genes and our environment
## Nervous system function is the product of genes and environment(s)
<div style="font-size:0.9em">
<div></div>
@@ -304,6 +378,8 @@ Note:
- language, learning to ride a bike
- clones, identical twins
Model the world in terms of entangled energy, entangled variances of polarized spatiotemporal change.
---
## Genome size does not predict nervous system complexity
@@ -316,6 +392,7 @@ organism | # of genes | # of base pairs | # of neurons | development time (you
*Caenorhabditis elegans* (nematode) | ~19,000 | ~97 million | 302 | 8 hrs
*Drosophila melanogaster* (fruit fly) | ~15,000 | ~120 million | ~250,000 | 7–11 days
*Danio rerio* (zebrafish) | ~24,000 | ~1.5 billion | ~10,000,000 | 30 days
*Xenopus tropicalis* (frog) | ~21,000 | ~1.7 billion | ~16,000,000 | 4 months
Mouse | ~25,000 | ~3.5 billion | ~71,000,000 | 2-3 months
Human | ~20,000 | ~3.5 billion | ~100,000,000,000 | 18 years
African elephant | ~20,000 | ~3.1 billion | ~267,000,000,000 | 18 years
@@ -333,10 +410,104 @@ Even number of base pairs: Paris japonica (white, star like flower) has 150 bill
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.
animal | n neurons | n synapse
--- | --- | ---
roundworm | 302 | 7500
jellyfish | 5600 |
sea slug | 18,000 |
amphioxus | 20,000 |
larval zebrafish | 100000 |
fruitfly | 250,000 | <10,000,000
ant | 250,000 |
honey bee | 960,000 |
cockroach | 1,000,000 |
guppy | 4,300,000 |
frog | 16,000,000 |
zebra finch | 131,000,000 |
brown rat | 200,000,000 | 4.48x10^11
red junglefowl | 221,00,000 |
ferret | 404,000,000 |
gray squirrel | 453,660,000 |
octopus | 500,000,000 |
sources for n neurons
* http://faculty.washington.edu/chudler/facts.html
* https://en.wikipedia.org/wiki/List_of_animals_by_number_of_neurons
E. Coli K-12: 4,639,221 bp, 4377 genes
Naegleria gruberi (unicellular free living eukaryote organism) 41 x 10^6 bp 15,727 genes
xenopus laevis | 3.1 billion bp | 16,948; 23,676 genes | ? neurons | 1 year | 1.3 mm egg
xenopus tropicalis | 1.7 billion bp | 21,634 genes | 16,000,000 neurons | 4 months | 0.8 mm egg
<https://www.xenbase.org/anatomy/intro.do>
xenopus genome project <http://viewer.shigen.info/xenopus/>
X. tropicalis develops faster with a higher optimal temperature (25-30°C vs 16-22°C), and has a diploid, smaller genome (instead of tetraploid) compared with X. laevis. Still has big eggs (0.8mm vs 1.2mm), large brood size (500-2000+) and large (but smaller) adults (4-5cm vs 10cm) as X. laevis
: gastrulation at 7-8hrs, tailbud at 20hrs and tadpole at 36hrs. Reproductive adults at 12mo.
: https://www.xenbase.org/anatomy/static/intro/xenopus_life_cycle_small.png
xenopus hatchlings
: can detect light intensity (pineal gland, then with eyes a few days later) Foster and Roberts 1982)
: discriminate touch (skin is excitable with cardiac-like all or none APs for a primitive noxious stimuli response like Cnidarians (Mackie 1970). Body surface innervated by touch neurons to trigeminal gangli and spinal cord (Roberts 1980)
: lateral line neuromasts caudal to eyes for water current responses by swimming into them (Roberts 2009)
: have few thousand functioning central neurons (populations of 20-150) on each side [Roberts:2010]
[Roberts:2010]: Roberts A, Li WC, Soffe SR. How neurons generate behavior in a hatchling amphibian tadpole: an outline. Front Behav Neurosci. 2010 Jun 24;4:16. doi:10.3389/fnbeh.2010.00016. PMID: 20631854; PMCID: PMC2903309.
Dictyostelium discoideum
: 34 Mb haploid genome, six chromosomes, 12500 genes
: soil dwelling amoeba, slime mold
: eukaryote transitioning between unicelular to multicellular slugs to fruiting body
: found in soil, moist leaf litter. diet is bacteria like E. Coli
: bacteria secretion of folic acid attracts the myxamoebae, which divide by mitosis during the vegetative stage why consuming bacteria
: mostly asexual lifecycle-- vegetative, aggregation, migration, culmination
: starvation during aggregation causes the myxamoebae to make glycoproteins that help cell-cell adhehsion and adenylyl cyclase which makes cAMP. cAMP works as a chemotactic signal, attracting neighboring amoebae then form a motile pseudoplasmodium, a slug up to 2-4mm long and 100000 cells
: https://upload.wikimedia.org/wikipedia/commons/thumb/3/3e/Cell-Shape-Dynamics-From-Waves-to-Migration-pcbi.1002392.s007.ogv/180px--Cell-Shape-Dynamics-From-Waves-to-Migration-pcbi.1002392.s007.ogv.jpg
: 5μm spores and amoebas to aggregated multicellular slugs of 1mm length
: sexual reproduction also possible. three mating types with three strains having different gene combinations that specify the three different sexes, can only mate with the two different sexes <https://doi.org/10.1126%2Fscience.1197423> u<https://pubmed.ncbi.nlm.nih.gov/21148389>
: https://en.wikipedia.org/wiki/Dictyostelium_discoideum
: during chemotaxis, cAMP and amoeba movements occur every six minutes with amoebae moving toward concentration gradient for 60s before stopping. Oscillations in groups of cells results with propogating spiral waves of varying cAMP concentrations http://www.whydomath.org/Reading_Room_Material/ian_stewart/2000_11.html
: may exhibit food husbandry or 'farming' behavior! https://doi.org/10.1038%2Fnature09668
* Drosophila 7-11 days (28-34degs C)
* zebrafish 3-4 days juvenile swimming and visual behavior. young adult at 3 mo. full adult at 6 mo.
* genome sizes at http://www.biology-pages.info/G/GenomeSizes.html
What about **cerebral cortical neuron number**?
* generally humans thought to have highest neocortical neuron number (and therefore greatest amount of cortical links, inter-connects)
* but cetaceans approach and even rival humans in these measures... dolphins, killer whales, blue whale
* indeed a study in the past decade revealed the long-finned pilot whale as having more neocortical neurons than human.
- Globicephala melas; latin "globe" and greek kephale "head"
- up to 6.7 m long, 2300kg. second larges delphinid next to the *Orcinus orca*
- very social, small long term social units of 8-12 individual, aggregates of 100s to 1000s of individuals observed. usually small familial pods.
- gestation 12 - 16 months, calives are up to 2.0 m at birth and 75kg
- sex maturity for females and males at eight and 12 years respectively
- <https://en.wikipedia.org/wiki/Long-finned_pilot_whale>
<https://en.wikipedia.org/wiki/List_of_animals_by_number_of_neurons#cite_note-80>
African elephant 5,600,000,000 Pallium (cortex) Loxodonta africana[^Herculano-Houzel2014]
Chimpanzee 7,400,000,000 Pallium (cortex) Pan troglodytes[^Collins2016]
Bottlenose dolphin 12,700,000,000 Pallium (cortex) Tursiops truncatus[^Herculano-Houzel2019]
Human 21,000,000,000 Pallium (cortex) Homo sapiens[^Herculano-Houzel2015]
Blue whale 15,000,000,000 Pallium (cortex) Balaenoptera musculus[^Herculano-Houzel2019]
Long-finned pilot whale 37,200,000,000 Pallium (cortex) Globicephala melas[^Mortensen2014]
Killer whale 43,100,000,000 Pallium (cortex) Orcinus orca[^Herculano-Houzel2019]
[^Collins2016]: Collins CE, Turner EC, Sawyer EK, Reed JL, Young NA, Flaherty DK, et al. Cortical cell and neuron density estimates in one chimpanzee hemisphere. Proc Natl Acad Sci U S A. (2016). 113:740–5. doi:10.1073/pnas.1524208113
[^Herculano-Houzel2014]: Herculano-Houzel S, Avelino-de-Souza K, Neves K, Porfírio J, Messeder D, Mattos Feijó L, et al. The elephant brain in numbers. Front Neuroanat. (2014). 8:46. doi:10.3389/fnana.2014.00046
[^Mortensen2014]: Mortensen HS, Pakkenberg B, Dam M, Dietz R, Sonne C, Mikkelsen B, et al. Quantitative relationships in delphinid neocortex. Front Neuroanat. (2014). 8:132. doi:10.3389/fnana.2014.00132
[^Herculano-Houzel2019]: Herculano-Houzel S. Longevity and sexual maturity vary across species with number of cortical neurons, and humans are no exception. J Comp Neurol. (2019). 527:1689–1705. doi:10.1002/cne.24564
[^Herculano-Houzel2015]: Herculano-Houzel S, Catania K, Manger PR, Kaas JH. Mammalian brains are made of these: A dataset of the numbers and densities of neuronal and nonneuronal cells in the brain of glires, primates, scandentia, eulipotyphlans, afrotherians and artiodactyls, and their relationship with body mass. Brain Behav Evol. (2015). 86:145–63. doi:10.1159/000437413
---
## There are many brain-specific and non-brain specific genes expressed in the nervous system
@@ -369,7 +540,11 @@ Mutation in a spindle pole gene call ASPM1 (altered mitosis during brain develop
<!-- <figure><img src="figs/Neuroscience5e-Fig-01.01-3R_562abf7.jpg" height="300px"><figcaption>Neuroscience 5e Fig. 1.1</figcaption></figure> -->
<figure><img src="figs/Bond-natgenet2002-fig1.jpg" height="350px"><figcaption>[Bond:2002](https://dx.doi.org/10.1038/ng995), see also Neuroscience 5e Fig. 1.1</figcaption></figure>
<figure><img src="figs/Bond-natgenet2002-fig1.jpg" height="350px"><figcaption>
[Bond:2002](https://dx.doi.org/10.1038/ng995), see also Neuroscience 5e Fig. 1.1
</figcaption></figure>
@@ -440,7 +615,11 @@ afrotheria
<div style="width:300px; margin:0 25px; float:left;">
<figure><img src="figs/glia-astrocyte.svg" width="300px"><figcaption>[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/)</figcaption></figure>
<figure><img src="figs/glia-astrocyte.svg" width="300px"><figcaption>
[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/)
</figcaption></figure>
<div style="float:left;"><img src="figs/glia-oligodendrocyte.svg" width="150px"><figcaption>JA, CC0</figcaption></div>
<div><img src="figs/glia-schwann.svg" width="100px"><figcaption>JA, CC0</figcaption></div>
@@ -537,7 +716,11 @@ Multiple sclerosis or MS is an example of a devastating CNS disease characterize
* Myelinate axons in peripheral nervous system (PNS)
* One axon per cell
<figure><figcaption class="big">Cross section through PNS nerve</figcaption><img src="figs/48_08SchwannMyelin_902bf3b.jpg" height="200px"><figcaption>[neuralcloud.it](http://neuralcloud.it)</figcaption></figure>
<figure><figcaption class="big">Cross section through PNS nerve</figcaption><img src="figs/48_08SchwannMyelin_902bf3b.jpg" height="200px"><figcaption>
[neuralcloud.it](http://neuralcloud.it)
</figcaption></figure>
Note:
@@ -581,7 +764,11 @@ Note:
<!-- <figure><img src="figs/Neuroscience5e-Fig-01.03-1R_444117f.jpg" height="500px"><figcaption></figcaption></figure> -->
<figure><img src="figs/neuron-soma.svg" height="350px"><figcaption>[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/)</figcaption></figure>
<figure><img src="figs/neuron-soma.svg" height="350px"><figcaption>
[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/)
</figcaption></figure>
Note:
@@ -740,7 +927,11 @@ Note:
<!-- <div style="width:250px; float:left;"><figcaption class="big">pyramidal neuron</figcaption><img src="figs/Neuroscience5e-Fig-01.02-1R-pyr-neuron_aa8d83c.jpg" height="400px"><figcaption>Neuroscience 5e Fig. 1.2</figcaption></div> -->
<div style="width:250px; float:left;"><figcaption class="big">pyramidal neuron</figcaption><img src="figs/pyramidal-neuron.svg" height="300px"><figcaption>[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/). see also Neuroscience 5e Fig. 1.2</figcaption></div>
<div style="width:250px; float:left;"><figcaption class="big">pyramidal neuron</figcaption><img src="figs/pyramidal-neuron.svg" height="300px"><figcaption>
[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/). see also Neuroscience 5e Fig. 1.2
</figcaption></div>
<div style="width:300px; float:left;"><figcaption class="big">pyramidal neurons</figcaption><img src="figs/golgi-pyr-neurons-fig19-nobel-lecture_b94e6d1.png" height="300px"><figcaption>C. Golgi, Fig. 19 Nobel lecture</figcaption></div>
@@ -774,7 +965,11 @@ Function of an **afferent** neuron is to carry information from the sensory peri
<!-- <figure><figcaption class="big">nociceptive (pain) neuron</figcaption><img src="figs/image28_d35899e.png" height="400px"><figcaption></figcaption></figure> -->
<figure><figcaption class="big">sensory neuron</figcaption><img src="figs/sensory-neuron.svg"><figcaption>[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/)</figcaption></figure>
<figure><figcaption class="big">sensory neuron</figcaption><img src="figs/sensory-neuron.svg"><figcaption>
[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/)
</figcaption></figure>
Note:
@@ -789,7 +984,11 @@ Function of an **efferent** neuron is to carry information towards the muscles f
<!-- <figure><figcaption class="big">alpha motor neuron</figcaption><img src="figs/image29_df57dca.png" height="400px"><figcaption></figcaption></figure> -->
<figure><figcaption class="big">motor neuron</figcaption><img src="figs/motor-neuron.svg"><figcaption>[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/)</figcaption></figure>
<figure><figcaption class="big">motor neuron</figcaption><img src="figs/motor-neuron.svg"><figcaption>
[JA, CC0](https://creativecommons.org/share-your-work/public-domain/cc0/)
</figcaption></figure>
Note:
@@ -920,7 +1119,6 @@ You might have the anatomy skills of Cajal or Golgi and you know there is this r
<figure><figcaption class="big">Extracellular electrode recordings showing action potential firing frequencies</figcaption><img src="figs/spinal-motor-reflex-extracellular.svg" height="350px"><figcaption>CC0, see also Neuroscience 5e Fig. 1.8, 1.9</figcaption></figure>
Note:
These ticks are spikes or action potentials recorded extracelluarly. Since the electrode tip is placed close to the neurons cell membrane, the electrode can pick up signals as they pass by. A little bit like someone wiretapping your phone line.

132
neuroanatomy2.md
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@@ -1,24 +1,40 @@
# Neural Systems
* Circuits that do the same kinds of things are grouped into 'systems', e.g. sensory systems and motor systems
* Many neurons function between these systems, called associational systems. Associational systems are the most complex and least well characterized systems.
* Circuits of interconnected components (neurons). Group structure (in space, time) for sub-systems concerned with sensory-input or motor-output.
* Many circuits function between these sub-systems, mediating functional interactions (associations) across modalities. Associational systems are the most complex and least well characterized neural sub-systems.
<div style="font-size:0.5em;">
2020-10-13T11:43:55-07:00
<!-- date: -->
<!-- date: -->
</div>
Note:
Last time we learned some of the basic cellular anatomy of the nervous system. Today we will put the system in nervous system–– because nervous systems really are greater than the sum of its parts… in other words our brain is not just a blob of cells but it is the interconnections between cells, groups of cells, and brain regions that allow our fantastic feats of emergent biological computation. So lets discuss the overall the structure of the nervous system.
Last time we learned some of the basic cellular anatomy of the nervous system. Today we will put the system in nervous system–– because nervous systems really are greater than the sum of its parts… in other words our brain is not just a blob of cells but it is the inter-connections between cells, groups of cells, and brain regions that allow our fantastic feats of emergent biological computation. So lets discuss the overall the structure of the nervous system.
First of all it is a system of systems. In other words…
--
## What is a system?
system (wn, noun)
: (a procedure or process for obtaining an objective;)
: (a group of independent but interrelated elements comprising a unified whole;)
: ((physical chemistry) a sample of matter in which substances in different phases are in equilibrium;)
: (a group of physiologically or anatomically related organs or parts; "the body has a system of organs for digestion")
: (the living body considered as made up of interdependent components forming a unified whole;)
Note:
---
## Major components of the nervous system and their functional relationships
<div><figcaption class="big">central nervous system (CNS)</figcaption><video height=200px controls loop src="figs/cns_overview.m4v"></video><figcaption>[C. Krebs CC BY-NC-SA, Univ. British Columbia](http://www.neuroanatomy.ca/3D_files/3D_index.html?id=1)</figcaption></div>
<div><figcaption class="big">central nervous system (CNS)</figcaption><video height=200px controls loop src="figs/cns_overview.m4v"></video><figcaption>
[C. Krebs CC BY-NC-SA, Univ. British Columbia](http://www.neuroanatomy.ca/3D_files/3D_index.html?id=1)
</figcaption></div>
<div><img src="figs/Neuroscience5e-Fig-01.10-1R_cfe2e3e.png" height="400px"><figcaption>Neuroscience 5e Fig. 1.10</figcaption></div>
@@ -59,8 +75,13 @@ Note:
## Common techniques to visualize brain structure
<div><figcaption class="big">Cell stain (e.g. Nissl/Cresyl violet, H&E)</figcaption><img src="figs/2240_cell_4aa2d7c.jpg" height="300px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
<div><figcaption class="big">Fiber stain (e.g. , Heidenhahn, Luxol fast blue)</figcaption><img src="figs/2240_fiber_d16bc49.jpg" height="300px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
<div><figcaption class="big">Cell stain (e.g. Nissl/Cresyl violet, H&E)</figcaption><img src="figs/2240_cell_4aa2d7c.jpg" height="300px"><figcaption>
[Brain Biodiversity Bank MSU, NSF](https://brains.anatomy.msu.edu/brains/human/coronal/montage.html)
</figcaption></div>
<div><figcaption class="big">Fiber stain (e.g. , Heidenhahn, Luxol fast blue)</figcaption><img src="figs/2240_fiber_d16bc49.jpg" height="300px"><figcaption>
[Brain Biodiversity Bank MSU, NSF](https://brains.anatomy.msu.edu/brains/human/coronal/montage.html)</figcaption></div>
Note:
@@ -111,7 +132,9 @@ Heidenhahn
## Magnetic resonance imaging (MRI)
<div><img src="figs/2240_cut_aaaa4be.jpg" height="200px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
<div><img src="figs/2240_cut_aaaa4be.jpg" height="200px"><figcaption>
[Brain Biodiversity Bank MSU, NSF](https://brains.anatomy.msu.edu/brains/human/coronal/montage.html)</figcaption></div>
<div><video height=400px controls src="figs/Animation01-01MagneticResonanceImaging_OC.mp4"></video><figcaption>Neuroscience 5e Animation 1.1</figcaption></div>
@@ -122,7 +145,7 @@ MRI
* Uses rotating magnets to generate image
* Non-invasive
* Can view images from any angle
* Resolution under 1 mm
* Resolution can be less than 1 mm
* Can be adapted to do functional MRI imaging
fMRI
@@ -156,7 +179,9 @@ Cortex
## Cell groupings: cortex vs nuclei
<figure><figcaption class="big">Cerebral cortex and thalamic nuclei</figcaption><img src="figs/2060_cell_abf6617.jpg" height="400px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/2060_cell_labelled.html)</figcaption></figure>
<figure><figcaption class="big">Cerebral cortex and thalamic nuclei</figcaption><img src="figs/2060_cell_abf6617.jpg" height="400px"><figcaption>
[Brain Biodiversity Bank MSU, NSF](https://brains.anatomy.msu.edu/brains/human/coronal/2060_cell_labelled.html)</figcaption></figure>
Note:
@@ -413,7 +438,9 @@ Also notice that 4 of the 12 nerves concern sensory and motor information from t
## Midbrain
<figure><img src="figs/mri_midbrain_170-labels_3f3d983.png" height="400px"><figcaption>[C. Krebs CC BY-NC-SA, Univ. British Columbia](http://www.neuroanatomy.ca/MRIs/mri_sagittal.html?id=1)</figcaption></figure>
<figure><img src="figs/mri_midbrain_170-labels_3f3d983.png" height="400px"><figcaption>
[C. Krebs CC BY-NC-SA, Univ. British Columbia](http://www.neuroanatomy.ca/MRIs/mri_sagittal.html?id=1)</figcaption></figure>
Note:
@@ -490,7 +517,7 @@ Neurons form cortical sheets like in the cerebral hemispheres.
Receives…
fyi: The MRI image is J. Ackman's brain back in 2009;)
fyi: The MRI image is J. Ackman's brain from 2009!
---
@@ -501,9 +528,15 @@ fyi: The MRI image is J. Ackman's brain back in 2009;)
<!-- <div><img src="figs/image10_cac162f.png" height="200px"><figcaption></figcaption></div> -->
<!-- <div><img src="figs/image11_ee714ea.png" height="200px"><figcaption></figcaption></div> -->
<div><img src="figs/2800_cell_cfb18b0.jpg" height="200px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
<div><img src="figs/2800_fiber_6135263.jpg" height="200px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
<div><img src="figs/golgi_purkinje-neuron-fig4-nobel-lecture_b18b837.png" height="200px"><figcaption>C. Golgi Fig. 4 Nobel lecture</figcaption></div>
<div><img src="figs/2800_cell_cfb18b0.jpg" height="200px"><figcaption>
[Brain Biodiversity Bank MSU, NSF](https://brains.anatomy.msu.edu/brains/human/coronal/montage.html)</figcaption></div>
<div><img src="figs/2800_fiber_6135263.jpg" height="200px"><figcaption>
[Brain Biodiversity Bank MSU, NSF](https://brains.anatomy.msu.edu/brains/human/coronal/montage.html)</figcaption></div>
<div><img src="figs/golgi_purkinje-neuron-fig4-nobel-lecture_b18b837.png" height="200px"><figcaption>
C. Golgi Fig. 4 Nobel lecture</figcaption></div>
@@ -563,9 +596,13 @@ Which connections gets through to neocortex without a thalamic relay? **neurom
## Thalamus– gateway to the cerebral cortex
<div style="width:400px"><figcaption class="big">Thalamus (brown), ventricles (blue)</figcaption><video height="250px" controls loop src="figs/thalamus.m4v"></video><figcaption>[C. Krebs CC BY-NC-SA, Univ. British Columbia](http://www.neuroanatomy.ca/3D_files/3D_index.html?id=1)</figcaption></div>
<div style="width:400px"><figcaption class="big">Thalamus (brown), ventricles (blue)</figcaption><video height="250px" controls loop src="figs/thalamus.m4v"></video><figcaption>
<div><figcaption class="big">Fiber stain</figcaption><img src="figs/2060_fiber-thalamus_207b466.png" height="250px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
[C. Krebs CC BY-NC-SA, Univ. British Columbia](http://www.neuroanatomy.ca/3D_files/3D_index.html?id=1)</figcaption></div>
<div><figcaption class="big">Fiber stain</figcaption><img src="figs/2060_fiber-thalamus_207b466.png" height="250px"><figcaption>
[Brain Biodiversity Bank MSU, NSF](https://brains.anatomy.msu.edu/brains/human/coronal/montage.html)</figcaption></div>
Note:
@@ -627,13 +664,16 @@ Limbic system includes the amygdala, as well as the part of the basal ganglia, p
* Organized into layers
* Greatly expanded in humans
[http://brainmuseum.org](http://brainmuseum.org)
[comparative mammalian brain anatomy museum](https://brains.anatomy.msu.edu/museum/brain/)
Note:
2500 sq cm in area or about 2.5 sq ft is the human cerebral cortex surface area:
2500 sq cm in area or about 2.5 sq ft is the human cerebral cortex surface area[^Toro2008]:
https://academic.oup.com/cercor/article/18/10/2352/384745
[^Toro2008]: Toro, Roberto; Perron, Michel; Pike, Bruce; Richer, Louis; Veillette, Suzanne; Pausova, Zdenka; Paus, Tomáš (2008-10-01). "Brain Size and Folding of the Human Cerebral Cortex". Cerebral Cortex. 18 (10): 2352–2357. doi:10.1093/cercor/bhm261. ISSN 1047-3211. PMID 18267953.
The little, but very compactly folded cerebellum has 80% of the surface area of cerebral cortex in humans. Compared with monkeys, there is evidence that the cerebellum went through a disproportionaly increased amount of surface area expansion during evolution than even the neocortex.
@@ -643,6 +683,40 @@ Sereno et al. PNAS 2020:
https://doi.org/10.1073/pnas.2002896117
cortical surface area
species | approx value
--- | ---
human | 2500 cm^2^
mouse | 2.5 cm^2^
rat | 6 cm^2^
afr. elephan | 6300 cm^2^
pilot whale | 5800 cm^2^
<http://faculty.washington.edu/chudler/facts.html>
--
## Cerebral folding
Tensional and compressive forces result in cerebral folding.
<div><img src="figs/2020-06-01-231346.png" width="400px"><figcaption>Tallinen:2016, Fig1
</figcaption></div>
<div><img src="figs/2020-06-01-231854.png" width="400px"><figcaption>Tallinen2016, Fig3a</figcaption></div>
Note:
* Tensegrity, tensional forces of long cellular processes (axon bundles), Felleman and Van Essen 1991 monkey neocortical/visual wiring map [^Felleman:1991]
[^Felleman:1991]: Distributed hierarchical processing in the primate cerebral cortex. pmid:1822724
Takes between 22 – 26 weeks of gestation (154 – 182d. or 5.1 – 6 mo.) before fissures and gyri start forming in the human brain (Tallinen Nature Physicis 2016). Between 33–37 weeks the convolutions take on the complexity seen in the newborn human brain (7.7–8.6 mo.).
[^Tallinen:2016]: On the growth and form of cortical convolutions. http://dx.doi.org/10.1038/nphys3632
---
## Cortico-cortical connection pathways
@@ -659,13 +733,21 @@ https://doi.org/10.1073/pnas.2002896117
</div>
<div style="margin-bottom:50px"><figcaption class="big">Fiber stain</figcaption><img src="figs/2240_fiber_d16bc49.jpg" height="200px"><figcaption>[Brain Biodiversity Bank MSU, NSF](https://msu.edu/~brains/brains/human/coronal/montage.html)</figcaption></div>
<div style="margin-bottom:50px"><figcaption class="big">Fiber stain</figcaption><img src="figs/2240_fiber_d16bc49.jpg" height="200px"><figcaption>
<div><figcaption class="big">Dorsal view</figcaption><img src="figs/Neuroscience5e-Fig-A11-1R_a8973d9_copy_9c648a7.jpg" height="200px"><figcaption>Neuroscience 5e Fig. A11</figcaption></div> <!-- .element: class="fragment fade-in"-->
[Brain Biodiversity Bank MSU, NSF](https://brains.anatomy.msu.edu/brains/human/coronal/montage.html)</figcaption></div>
<div><figcaption class="big">Dorsal view cut away</figcaption><img src="figs/Neuroscience5e-Fig-A11-3R_17d31f5_copy_406b96a.jpg" height="200px"><figcaption>Neuroscience 5e Fig. A11</figcaption></div> <!-- .element: class="fragment fade-in"-->
<div><figcaption class="big">Dorsal view</figcaption><img src="figs/Neuroscience5e-Fig-A11-1R_a8973d9_copy_9c648a7.jpg" height="200px"><figcaption>
<div><figcaption class="big">MRI-DTI dorsal projection</figcaption><img src="figs/Neuroscience5e-Ch01-Opener_497d461_copy_b20f743.jpg" height="200px"><figcaption>Neuroscience 5e</figcaption></div> <!-- .element: class="fragment fade-in"-->
Neuroscience 5e Fig. A11</figcaption></div> <!-- .element: class="fragment fade-in"-->
<div><figcaption class="big">Dorsal view cut away</figcaption><img src="figs/Neuroscience5e-Fig-A11-3R_17d31f5_copy_406b96a.jpg" height="200px"><figcaption>
Neuroscience 5e Fig. A11</figcaption></div> <!-- .element: class="fragment fade-in"-->
<div><figcaption class="big">MRI-DTI dorsal projection</figcaption><img src="figs/Neuroscience5e-Ch01-Opener_497d461_copy_b20f743.jpg" height="200px"><figcaption>
Neuroscience 5e</figcaption></div> <!-- .element: class="fragment fade-in"-->
Note:
@@ -802,6 +884,8 @@ So first lets discuss how we came to define different parts of the brain, specif
Note:
todo: replace figure
He used cell body staining like the Nissl stain to examine differences in general patterning/layering across the cerebral cortex.

59
neurophysiology1.md
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@@ -6,7 +6,9 @@
* Synaptic transmission
* Neurotransmitters, receptors, and their effects (second messenger systems, molecular signaling within neurons)
<div style="font-size:0.5em;">
<!-- date: -->
</div>
Note:
@@ -61,7 +63,9 @@ Flow rate ~ Current (amperes) = `I`
</div>
<div style="margin:0 15px"><img src="figs/ScreenShot2016-01-10at3.49.52PM_f9a9f96.png" height="300px"><figcaption>M. Banzi Fig. 4-4, *Getting Started with Arduino* isbn:9781449363338</figcaption></div>
<div style="margin:0 15px"><img src="figs/ScreenShot2016-01-10at3.49.52PM_f9a9f96.png" height="300px"><figcaption>
M. Banzi Fig. 4-4, *Getting Started with Arduino* isbn:9781449363338</figcaption></div>
@@ -77,15 +81,15 @@ Voltage
*voltmeter, ammeter*
Current
: measured in amperes is the flow of electric charge across a surface at the rate of one coulomb per second. Used to express the flow rate of electric charge.
: measured in amperes is the flow of electric charge across a surface at the rate of one coulomb per second. **Used to express the flow rate of electric charge**.
: So imagine the rate of water flow in this water pump as the the flow of electric charge across a cell membrane. What is the charge that is moving for a cell? Monovalent and divalent atoms like Na⁺, K⁺, Cl⁻, and Ca²⁺.
*1A equivalent to one coulomb (roughly 6.241×10^18 times the elementary charge) per second*
*coulomb = charge (symbol: Q or q) transported by a constant current of one ampere in one second. 1C equivalent to a charge of approximately 6.242×10^18 protons or electrons.*
*elementary positive charge: This charge has a measured value of approximately 1.6021766208×10^−19 coulombs*
- *1A equivalent to one coulomb (roughly 6.241×10^18 times the elementary charge) per second*
- *coulomb = charge (symbol: Q or q) transported by a constant current of one ampere in one second. 1C equivalent to a charge of approximately 6.242×10^18 protons or electrons.*
- **elementary positive charge: This charge has a measured value of approximately 1.6021766208×10^−19 coulombs**
Resistance
: is the difficulty to pass a current through a conductor measured in ohms.
: **is the difficulty to pass a current through a conductor measured in ohms.**
: Image the diameter of a pipe or a valve that you can regulate to be the resistance
: inverse of resistance is conducance *g* measured in siemens (S)
: for studying neuronal excitability rewriting Ohm's law as I = g(Vm-Ex) is most useful. g = conductance, no. of open channels. (Vm-Ex) = driving force causing either positive or negative current.
@@ -114,21 +118,23 @@ electricity
## Electrical signals
* Can be generated by changing the membrane potential of the neuron
* Receptor potentials can be generated from the activation of sensory receptors, from touch, light, sound, and heat
* Generated by changing the membrane potential of the neuron
* Receptor potentials can be generated from the activation of sensory receptors: from touch, light, sound, taste, heat...
* Synaptic potentials are generated at the post-synaptic membrane between two neurons
* Action potentials are the high-amplitude, fast timing, regenerative signal that propagate a long distance
* Action potentials are the high-amplitude, fast timing, regenerative signals that propagate a long distance
Note:
Signals in neurons can be generated by changing the membrane potential.
This includes receptor potentials inside your body’s sensory neurons for touch, heat, light, and sound.
And synaptic potentials are the changes in membrane potential at synapses that underly the transfer of information from neuron to neuron.
Action potentials are the large electrical spikes or impulses that allow neuronal signals to propagate over long distances, including nerves centimeters to meters long.
signal (wn, noun)
: an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes
---
## Types of electrical signals in neurons
@@ -150,7 +156,7 @@ To understand the basis of these electrical signals we first need to learn about
---
## What is baseline? The resting membrane potential of neurons
## What is baseline? The "resting" membrane potential of neurons
<div style="font-size:0.9em;">
<div></div>
@@ -170,7 +176,7 @@ Note:
I said that the resting membrane potential is more negative inside the neuron with respect to its extracellular space– this is because of the lipid bilayer and its transmembrane proteins which together make a functional cell membrane
We can think of the cell, a bit like American politics, is polarized with one side more negative and the other being more positive
We can think of the cell, a bit like American politics, is polarized.
This polarization of the cell results in a potential difference across the membrane (remember our water pump example) of about -70 mV
@@ -289,7 +295,9 @@ There are also ion channels that form pores in the cell membrane that are select
* Requires ATP
* Helps set up the ion concentration gradients and resting membrane potential
<div><img src="figs/alberts_fig11-10-NaKatpase_f8e7b70.png" height="300px"><figcaption>Alberts *Mol Biol of the Cell* 3e Fig. 11-10</figcaption></div>
<div><img src="figs/alberts_fig11-10-NaKatpase_f8e7b70.png" height="300px"><figcaption>
Alberts *Mol Biol of the Cell* 3e Fig. 11-10</figcaption></div>
Note:
@@ -713,7 +721,6 @@ That is semipermeable containers with some capactity for self-replication
| calcium (Ca<sup>2+</sup>), squid | 0.0001 | 10 | 100000 |
| calcium (Ca<sup>2+</sup>), mammal | 0.0001 | 1–2 | 10000 |
<figcaption>see also Neuroscience 5e Table 2.1</figcaption>
</div>
@@ -764,9 +771,13 @@ Alan Hodgkin, Andrew Huxley, Bernard Katz
## Squid giant axon
<div><img src="figs/Squid_Loligo_pealei_cbafe46.jpg" height="300px"><figcaption>Atlantic squid, *Loligo pealei*</figcaption></div>
<div><img src="figs/Squid_Loligo_pealei_cbafe46.jpg" height="300px"><figcaption>
<div><iframe src="https://www.youtube.com/embed/I6jxrxcLxiI" width="560" height="315"></iframe><figcaption>Squid giant axon electrophysiology</figcaption></div>
Atlantic squid, *Loligo pealei*</figcaption></div>
<div><iframe src="https://www.youtube.com/embed/I6jxrxcLxiI" width="560" height="315"></iframe><figcaption>
Squid giant axon electrophysiology</figcaption></div>
Note:
@@ -775,7 +786,9 @@ Note:
## K⁺ concentration gradient determines resting membrane potential
<figure><img src="figs/Neuroscience5e-Fig-02.08-0_40bc007.png" height="400px"><figcaption>Neuroscience 5e/6e fig. 2.8; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
<figure><img src="figs/Neuroscience5e-Fig-02.08-0_40bc007.png" height="400px"><figcaption>
Neuroscience 5e/6e fig. 2.8; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
Note:
@@ -829,7 +842,9 @@ Their experiment was to lower Na concentrations in the extracellular medium—
## The action potential as measured by Hodgkin, Huxley, and Katz
<figure><img src="figs/hodkin-huxley-nature-1939-AP_d30dfee.png" height="400px"><figcaption>Adapted from Hodgkin and Huxley *Nature* 1939</figcaption></figure>
<figure><img src="figs/hodkin-huxley-nature-1939-AP_d30dfee.png" height="400px"><figcaption>
Adapted from Hodgkin and Huxley *Nature* 1939</figcaption></figure>
Note:
@@ -847,7 +862,9 @@ Capacitance (farads)
## Role of sodium in the generation of an action potential
<figure><figcaption class="big">Lowering Na⁺ decreases both the rate and the rise of an action potential</figcaption><img src="figs/Neuroscience5e-Fig-02.09-1R_2c02203.png" height="400px"><figcaption>Neuroscience 5e/6e Fig. 2.9; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
<figure><figcaption class="big">Lowering Na⁺ decreases both the rate and the rise of an action potential</figcaption><img src="figs/Neuroscience5e-Fig-02.09-1R_2c02203.png" height="400px"><figcaption>
Neuroscience 5e/6e Fig. 2.9; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
Note:
@@ -858,7 +875,9 @@ When Hodgkin and Katz did this low extracellular Na experiment, the AP had a sma
## Role of sodium in the generation of an action potential
<figure><img src="figs/Neuroscience5e-Fig-02.09-2R_6ca6c4f.png" height="400px"><figcaption>Neuroscience 5e/6e Fig. 2.9; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
<figure><img src="figs/Neuroscience5e-Fig-02.09-2R_6ca6c4f.png" height="400px"><figcaption>
Neuroscience 5e/6e Fig. 2.9; Hodgkin and Katz *J. Physiol* 1949</figcaption></figure>
Note: