PENS Summer School - University of Geneva 2013
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EEG neurofeedback: methods and mechanisms Tomas Ros, PhD Laboratory for Neurology & Imaging of Cognition University of Geneva, Switzerland
Transcript of PENS Summer School - University of Geneva 2013
EEG neurofeedback: methods and mechanisms
Tomas Ros, PhD Laboratory for Neurology & Imaging of Cognition University of Geneva, Switzerland
The Big Picture
Is the brain like a computer ?
Software = Functional activity Hardware = Structural architecture
Brain = “Wetware” Brain function ⟺ Brain structure Software ⟺ Hardware
4
Many windows, one brain: the six blind men and the elephant
Pics - EEG: Brain Sci. Institute Swinburne; MEG: Dept. of Psychology NYU;
fMRI: Dept. Cog. Neurology, MPI Leipzig; SPECT: C. Studholme UCSF;
PET: N.D. Volkov et al.; Anatomy: NTVH MRI Lab; Poem: Wordinfo.
SPECT
EEG
MEG
fMRI
PET
Anatomy
Intersecting forms of brain plasticity: Functional e.g. neuronal firing patterns
Chemical e.g. number of synaptic receptors
Structural e.g. grey and white matter volume
Functional plasticity (lasting change in neuronal firing)
Ghosh et al (2013), J Neuroscience
Chemical plasticity (no. of receptors at synapse)
McNab et al (2009), Science
Brain = Wetware Software ⟺ Hardware
Brain function ⟺ Brain structure
How to guide brain plasticity?
Control requires feedback !
Sense Vehicle Speed
Compute Control “Law”
Actuate Gas Pedal
Feedback Loop
Control = Sensing + Computation + Actuation
Note: the system can control only observable parameters
“Cruise Control”
A Brain-Computer Interface (BCI)
Computation
Sensing
Actuation
A Brain-Computer Interface (BCI)
Computation
Control
Detection
The neurofeedback “loop”
REFERENCE VALUE
FEEDBACK
EEG is generated by synaptic activity
EEG and behavioral states
Sterman et al., Science (1970)
EEG in Attention-Deficit Disorder
Sohn et al., Clin Neurophys (2010)
The missing link?
• Current evidence involves multiple sessions of NFB
in healthy subjects : >8 sessions
for clinical application: >20 sessions
• Is there a neuroplastic effect following a single
session of NFB ?
How to study brain plasticity non-invasively ?
TMS allows the
safe, non-invasive
and painless
stimulation of the
human cortex
Transcranial magnetic stimulation (TMS)
TMS stimulation of motor cortex evokes muscle activity
MEP: recording of muscle contraction activity using surface electrode.
TMS
Experimental timeline
30-min NFB
10 9 8 7 6 5 4 3 2 1
time (training period)
8.25
8.00
7.75
EEG
am
plit
ud
e (
mic
roV
)
C R = -ve
B R = 0
A R = +ve
Correlation coeff:
EEG amplitude vs.
Training period
A
B
C
Neurofeedback training coefficient
↑ excitability ↓ alpha EEG
Ros et al, Eur J Neuroscience (2010)
Neurofeedback training coefficient vs
motor-evoked potential (MEP)
3-way scatterplot
R > +0.6
R < -0.6 R < -0.6
Δtraining EEG α
Δresting EEG α
ΔMEP
Ros et al, Eur J Neuroscience (2010)
Can neurofeedback modulate the
brain’s functional networks?
Simultaneous EEG-fMRI (Jann et al 2009)
Mind-wandering and default-mode network (Stawarczyk et al 2011)
Protocol: desynchronizing alpha rhythm (8-12 Hz) at Pz
Real-neurofeedback: n=17
Sham-neurofeedback: n=17
Ros et al, Neuroimage (2013)
Timeline
30-min NFB attention task attention task
Ros et al, Neuroimage (2013)
alpha amplitude (8-12 Hz)
Ros et al, Neuroimage (2013)
EEG topography during neurofeedback
Ros et al, Neuroimage (2013)
Neurofeedback EEG change vs
resting EEG change
Mind wandering change vs
resting alpha change
NFB
SHAM
NFB
SHAM
Ros et al, Neuroimage (2013)
(Wen et al, J Neurosci 2013)
(Salience Network)
(Default Mode Network)
What are the advantages of EEG neurofeedback?
SAFETY:
• Only processes that are naturally intrinsic to the brain are harnessed.
EFFICACY:
• The cortical effects of NFB seem comparable to those attained by exogenous non-invasive brain stimulation methods (rTMS / tDCS).
COST:
• EEG neurofeedback unit cost can be as low as $100.
LONG-TERM STABILITY:
• NFB modulates the brain “from within”, without external agents;
this may minimize tolerance effects of the nervous system.
SAFETY
EFFICACY
NFB +30% rTMS (repetitive pulse)
published safety guidelines for rTMS
Frequency
(Hz)
Max.
duration (s)
1 1800+
5 10
10 5
20 1.6
25 .84 Pascual-Leone et al, Exp Brain Res (2000)
tDCS (transcranial direct current stimulation)
NFB 130%
Nitsche & Paulus, Neurology (2001)
COST
• Price: ≈ 300 USD
• Price: ≈ 300 USD
Consumer-grade BCI Devices Price: ≈ 300 USD
LONG-TERM STABILITY
Research in Autism Spectrum Disorders (2008)
