Observing the brain to know ourselves

Sara A. Solla

Northwestern University

The human brain

The human brain

Neurons

About 85 billion neurons,

of which about 15 billion

are in the cortex.

Neurons

Neurons

electrode

Spikes: action potentials

Spikes: from single neurons

to multiple neurons

Multi Electrode Arrays (MEAs)

Reaching tasks

Center out task

MEA recordings: center out task

MEA recordings: multiple targets

Converting thoughts into actions

Nicolelis, Nature Reviews Neuroscience (2003)

Brain machine interfaces Idea first proposed by Edward M. Schmidt in 1980: `Single

neuron recording from motor cortex as a possible source of

signals for control of external devices’.

Schmidt, Annals of Biomedical Engineering (1980)

Multi Electrode Arrays (MEAs)

Truccolo, Hochberg, Donoghue, Nature Neuroscience (2009)

Activity: multiple neurons

110 neurons, M1, hS3

Brain machine interfaces

Neuroprosthesis

Hochberg, Serruya, Friehs, Mukand, et al, Nature (2006)

Neuroprosthesis

MEA recordings: center out task

Target-dependent population activity

fi =ni

D

Here is the number of spikes

emitted by neuron i during a time

bin of duration .

ni

D

Decoding direction of motion

for center out task

Predicting motion from neural activity

Simultaneous recordings of population activity

provide insight on the activity of networks of neurons

and its relation to function.

The ability to simultaneously record and decode the

activity of large populations of neurons provides a tool for

the restoration of function.

The mathematical analysis of neural activity associated

with arm reaches allows us to predict motion trajectory.

• Incorporate realistic limb dynamics into forward pathway

• Incorporate proprioception in feedback pathway

Bidirectional Brain Machine Interface