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 !