The wonderworld of the healthy brain

Dr Katrin Deinhardt

University of Southampton

http://www.iflscience.com/categories/brain

Image courtesy of the National Institute on Aging/National Institutes of Health

The human brain in numbers

• ~1.4 kg (~2% of the total body weight)

• 1011 (100,000,000,000) individual nerve cells

• 1014-1015 (1,000,000,000,000,000) connections

• Estimates of storage capacity vary from 10-1000 terrabytes

• In comparison: The entire collection of the US Library of Congress is estimated at 10tb

Ramon y Cajal

The beginnings..

Current initiatives to explore the (human) brain

• The Blue Brain Project:http://bluebrain.epfl.ch/

• The Human Connectome:http://www.humanconnectomeproject.org/http://www.humanconnectome.org/

• The Brain Initiative:http://www.nih.gov/science/brain/http://www.kavlifoundation.org/brain-initiative

The Blue Brain Project

• Aim : building a virtual brain in a supercomputer

• Challenge : each simulated neuron requires a computing power equivalent to that of an average laptop

• Benefit : the ability to simulate how changes in one brain area affect the entire network

• Started in 2002

• Developed a realistic model of a rat cortical column (a “building block” of the cortex; ~10,000 nerve cells) with ca 50 different neuronal subtypes by 2006

The Human Connectome Project

• Aim : to generate a wiring diagram of the living human brain (structural and functional)

• Challenge : to access the brain without causing damage

• Benefit : to gain an understanding of pathways underlying behaviour

• Since 2010

• 1200 healthy individuals

• Imaging techniques:

– hardwiring: resting functional MRI, diffusion imaging

– function: functional MRI; MEG/EEG on 100 individuals

– general shape: structural MRI

Diffusion imaging

Images courtesy of: http://humanconnectome.org

Images courtesy of: http://humanconnectomeproject.org

Functional MRI: listening to a story (yellow/red), and performing math

(blue/green)

Images courtesy of: http://humanconnectome.org

Structural MRI

Images courtesy of: http://humanconnectome.org

…put together:

Images courtesy of: http://humanconnectome.org

The Brain Initiative

• Aim : “To revolutionise our understanding of the human brain”“to accelerate the development and application of new technologies that will enable researchers to produce dynamic pictures of the brain that show how individual brain cells and complex neural circuits interact at the speed of thought”

• Challenge : Current technologies are limited

• Benefits : better basic understanding of brain function to develop treatments for brain disease

• Launched 2013

• Promotes new technologies and interdisciplinary research (engineering, informatics, biology etc)

• Brings together initiatives such as the connectome, the Allan Institute

“new technologies” – what can we do today in model organisms?

Some commonly used model organisms in numbers:

• C.elegans (roundworm): 302 neurons, ~5,000 synapses

• D.melanogaster (fruitfly): ~100,000 neurons, ~10,000,000 synapses

• M.musculus (mouse): ~71,000,000 neurons, ~100,000,000,000 synapses

• R.norvegicus (rat): ~200,000,000 neurons, ~450,000,000,000

Ramon y Cajal

Livet et al, Nature 2007

Imaging all nerve cells: The “brainbow” mouse

“Clarity”

Chung et al, Nature 2013

Chung et al, Nature 2013

…and we can watch and manipulate live: “optogenetics”

• Sensors: Chameleon (Ca2+), Mermaid (voltage)

• Manipulators: Light-activated channels switch nerve cells “on” or “off”

So what is my specific interest?

To understand how an individual nerve cell functions: working with large distances and complicated shapes

Long-range logistics: Transport

Local decisions: to grow or not to grow?

Local decisions: to grow or not to grow?

Finally…

…a great website for good “brain-related” info:

https://www.dana.org/

(also the neuroscience societies: BNA, FENS, SfN)