From Mouse to Human

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From the course by Hebrew University of Jerusalem

Synapses, Neurons and Brains

673 ratings

Hebrew University of Jerusalem

Synapses, Neurons and Brains

673 ratings

These are very unique times for brain research. The aperitif for the course will thus highlight the present “brain-excitements” worldwide. You will then become intimately acquainted with the operational principles of neuronal “life-ware” (synapses, neurons and the networks that they form) and consequently, on how neurons behave as computational microchips and how they plastically and constantly change - a process that underlies learning and memory. Recent heroic attempts to realistically simulate large cortical networks in the computer will be highlighted (e.g., “the Blue Brain Project”) and processes related to perception, cognition and emotions in the brain will be discussed. For dessert we will deliberate on the future of brain research, including the questions of “brain and art”, consciousness and free will. For more information see the course promo below and read “About the course.”

From the lesson

Cortical Networks - Out of the Blue Project

This module is based on what you have learned in modules 3 to 6: how single cells function, how they are connected via (plastic) synapses to each other and how they might perform specific computations. Here we actually connect a network of neurons (using the “blue machine super computer”) so that we can simulate mathematically the activity of a large network (the “Blue Brain Project” BBP centered in EPFL, Lausanne, Switzerland). We know how to simulate a single neuron (the Hodgkin and Huxley model) and how to simulate synapses and dendritic cable (Wilfrid Rall model) so we can connect neuron models and build realistic networks in the computer. We started with simulating the mammalian neocortex, a relatively new structure in evolution (200 million years old). In each cubic mm of the neocortex (e.g., of rat), there are about 100,000 cells, 4 Km of wires (dendrites and axons) and about 100 million synapses. We can today integrate experimental data (anatomical and physiological) and mathematical methods, and come close to simulating the electrical and synaptic activity in several cubic mm of the neocortex. We will learn about the neocortex - including the neuron types it consists of - and how we go about simulating such a huge neural circuit. We will next discuss what could we learn from it and what are we aiming at next. We will end by describing the recently announced, EU Flagship Project – the “Human Brain Project” (HBP). The BBP served as a seed for the HBP, but the latter is much broader and even more ambitious, aiming at developing new approaches for treatments of brain diseases (so urgently needed) and advancing the future of neuroscience and of brain-inspired computing and robotics.

Mega Projects for the Brain12:14

The Blue Brain Project - The Start12:55

The Cortical Column12:53

A Cortical Column Networks11:57

Blue Brain Simulations9:44

From Mouse to Human5:49

The Human Brain Project12:03

Meet the Instructors

Idan Segev
Professor
Computational Neuroscience

We have, we have today a generic column of a rat, built from 10,000 cells.

We can now connect different columns to each other.

Composing ten columns or so. Simulating the electrical activity of ten

columns like this. Receiving a particular input, looking at

the activity, trying to understand the collective activity due to this

connectivity and electrical properties of synapses and neurons.

But this is from the mouse, and of course, a natural question will come, so

what about humans? And there are several places in the

world. one unique one.

Is in Amsterdam in the fine university. A group there is working in the hospital

with patients, where by the patient is, has a tumor, or maybe has a, an epileptic

seizure and you have to take out. Piece of a brain.

So this is a brain of a human, with a particular region that you have to go

through. So the physician takes on the way, on the

way to this region. He takes out parts of the cortex of the

patient. Sometimes a big part.

Look at the brain of human versus the brain of a mouse, so sometimes a big part

like this. And so this is this group from from

Amsterdam. They receive from the physician a big

chunk of human cortex, which is a very rare material.

Only comes from hospitals. Living, cortical, human brain.

And then, because this piece had to be taken out for purposes of of, of

medicine, or because of the, of the epileptic seizure, or because of the

tumor, you have to take this piece out. Then you can do classical recording.

You can see a cell from a, a pyramidal cell from human.

The cell body, the dendrites look very similar to the mouse, bigger with more

synapses. You can reconstruct the apical tree, the

basal tree. You can do really a full complete

anatomy, as you know, you can see the layers.

Layer one, two, three and so forth. You already know about the layers and you

can really characterize, like Monica Hall already did, but this is now a living

material. And then, you can both do anatomy

reconstructing the cells, but you can also do physiology.

Recording the spikes from this cell, from this cell, from this cell, and also from

pairs of cells trying to see who is connected to who, and so you really can

start to get. A human cortical column so we are aiming

of course at simulating the human cortical column in the Blue Brain

project. But here is some limitation.

So I show you the computing speed. How many operations per second, these

large, big supercomputers can do. We are somewhere here today, we are

somewhere here. And so we can, we can simulate about 100

cortical columns, as I said using the present state art computers.

But, in order to really reconstruct and, I mean simulate mathematically, a whole

human brain, we need something much more powerful, probably a million times more

powerful than present day computers can do.

So we cannot use present day computers. To eventually simulate a whole human

brain and then try using this simulation to understand the activity within the

whole brain associated with a particular disease.

We can simulate a column, several columns of humans.

This will be hopefully enough to already understand some diseases emerging within

sub-networks. So what happens here?

This is the big problem of computers today.

You may know that increasing the speed by a million to exo-flop, exo-scale

computation relative to the petaflop. Or actually the teraflop, we can do

today, this is a big jump. This is the red jump, which is very, very

difficult. And there are lot of companies, and a

lot, a lot of attempts, to get to this scale, within ten years.

So we are, we are here somewhere. We are trying to go there, in terms of

simulating, the whole human brain. We are hoping, that due to, developments,

in the computing world, but also due to The Human Brain Project, we will be able

to develop, new technologies. Maybe even inspired by the brain, to be

able to simulate the human brain itself. So you can see that the human brain have,

to generate technologies, perhaps inspired by understanding its own brain,

in order to be able eventually, to simulate and understand In terms of

simulation-based research the brain of the human itself.

So let's go and complete this lecture by talking about The Human Brain Project.

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