Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Reconstruction and Simulation of Neocortical
Microcircuitry
Presented by: Ardi Tampuu
Institute of Computer Science, University of Tartu
November
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Blue Brain and Human Brain Project
The e�ort to reverse engineer and simulate themammalian/human brain.
Since 1995.
"What I cannot create, I do not understand"
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
The �rst results
This article is a �rst large-scale simulation published by thegroup (after 20 years of work).
• 0.3mm3
• 31 000 neurons
• 37 million synapses
• 207 neuron types
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Video abstract
Let's go to YouTube !
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Building the cortical tissue
There is a lot of knowledge that has to be gathered before wecan build a brain.
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Neuron Morphology
The shapes of neurons are important (at least biologists thinkthey are).
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Neurons' Electrical behaviour
The shape is not the only thing that de�nes behaviour.Di�erent densities of 13 types of ion (Na+, Ca2+, K+)channels on di�erent branches.
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Neurons' Electrical behaviour
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Putting Neurons Together
The di�erent morphological and electrical types are notuniformly distributed along the 2mm thick tissue.
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Putting Neurons Together
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Putting Neurons Together
Being near does not mean being connected. Next step is to�gure out who talks to who, where, how loudly..
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Putting Neurons Together
Being near does not mean being connected. Next step is to�gure out who talks to who, where, how loudly..
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Putting Neurons Together
Nothing is simple in biology. Not all connections are the same.
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Success ! !
After 20 years of work we (Homo Sapiens) have done this !
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Yeah right it works
There were so many things they could have done wrong. Whatkind of a mess does this thing produce ?
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Spontaneous activity
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Synchronization depends on Ca2+ levels
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Adding input from thalamus
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Adding input from thalamus
Behaviour of the network when getting input from thalamus isbest visualized with videos
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Balance of currents
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Spatial segregation
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
What have we achieved ?
There are some results we are fairly sure about :
• conductances are underestimated by in vitro experiments
• cell density is higher than usually thought
• the e�ect of individual layers, neuron types, synapse types,ion concentrations
• estimations : 20 % connections are from local circuitry, 1%from thalamus, rest from other distant sources
• asynchronous activity is caused by anti-correlated inhibition
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
What else could this thing be useful for ?
The model makes many predictions that we can trust blindly orverify by killing more rats.
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Why don't people like my arti�cial brain ?
• it costs 100 000 000 000 Euro cents
• there is other stu� in the brain � blood vessels, glial cells,gap junctions..
• though using well speci�ed distributions, it's still randomconnectivity - no functional restrictions
• maybe simpler models can do the same or better ?(Complexity for complexity's sake ?)
• are we even sure this is useful ?
Reconstruction
and
Simulation of
Neocortical
Microcir-
cuitry
Presented
by: Ardi
Tampuu
Introduction
Methods
Results
Thanks !
Thank you for your attention !
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