microstimulation on cortical

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The effects of electrical
microstimulation

on cortical
signal propagation

Nikos K
Logothetis
, Mark
Augath
,
Yusuke Murayama


nature neuroscience: 5 September 2010

1

G
lossary


Functional Magnetic Imaging (
fMRI
)


Blood Oxygen Level
-
Dependent (BOLD)


Positive/
Negetive

BOLD responses (PBRs/NBRs)


Thalamic region:


Lateral
Geniculate

Neucleus

(LGN)


Superior
Colliculus

(SC)


Pulvinar

(PUL)


Primary visual cortex (v1)


Extrastriate

cortex:


Secondary visual cortex (v2)


XC that refers to V3, V3A, V4, V4T,
posterir

TEO


MT (v5)


2

Results


E
lectrical stimulation disrupts
cortico
-
cortical signal
propagation by silencing the output of any neocortical area
whose afferents are electrically stimulated.




Scientific Basis:


S
timulation of a site in the LGN increased the
fMRI

signal in
the regions of V1 that received input from that site, but
suppressed it in the
retinotopically

matched regions of
extrastriate

cortex.


A short excitatory response occurring immediately after a
stimulation pulse was followed by a long
-
lasting inhibition.

3

a)
t static maps for LGN
stimulation.




b)
Time course of the BOLD
fMRI

responses in different
visual structures during LGN
stimulation.



c)
t

statistic maps for
pulvinar

stimulation.



d)
Time course of the BOLD
fMRI

responses in different
visual structures during
pulvinar

stimulation.

4

Combined visual and electrical stimulation of the LGN

a
) t
statistic maps, b) Time course of the BOLD
fMRI

responses, c) Average BOLD responses.

5

Effects of stimulation frequency on the BOLD responses

a) Upper traces show
typical V1 (red,
positive) and V2
(blue, negative)
responses during LGN
stimulation. Inset
shows
activeted

(V1,
red) and deactivated
(V2,
bluse
) areas.

b)
Combined visual and
electrical stimulation
at 12Hz.

c)
BOLD responses in
areas V1 and V2 for
visual and electrical
stimulation at
different frequencies.

6

Neural responses to single electrical pulses

a)
Raster plots and
peristimulus

histograms.



b)
PCA



c)
K
-
means clustering.



d)
C1
-
3 clusters powers.



e)
Electrode depth of the
recorded sites of each cluster.



f)
Pulse efficiency.



g)
Inter
-
pulse spiking activity.

7

Conclusion


The authors found that electrical stimulation of a thalamic site
suppressed the neural activity of its projection regions in
visual cortex.


The magnitude of the suppression depended on stimulation
frequency.


This effect was independent of current strength.


Intracrotical

recordings in V1 showed that an electric pulse
typically evoked an action potential followed by a pronounced
and long
-
lasting inhibition.


Stimulation of LGN consistently activated superior
colliculus

and
pulvinar
, even though neither structure receives direct
LGN input.

8

Strong claim in the paper!


“We

propose

that

many

of

the

behavioral

effects

that

have

been

observed

over

the

years

following

electrical

stimulation

of

the

afferents

of

sensory

or

association

cortical

areas

are

in

fact

largely

mediated

by

cortico
-
subcortico
-
cortical

pathways
.







Corresponding

author
:





Nikos

K

Logothetis




E
-
mail
:

Nikos
.
logothetis@tubingen
.
mpg
.
de




http
:
//www
.
kyb
.
mpg
.
de/




Max

Planck

Institute

for

Biological

Cybernetics,

Tubingen,





Germany
.


9