Attenuation

of

amplitude

of

laser-evoked

potentials

by

theta

burst

stimulation

of

primary

somatosensory

cortex

Theta

burst

stimulation

-LRB-

TBS

-RRB-

is

a

special

repetitive

transcranial

magnetic

stimulation

-LRB-

rTMS

-RRB-

paradigm

where

bursts

of

low-intensity

stimuli

are

applied

in

the

theta

frequency

The

aim

of

this

study

was

to

investigate

the

effect

of

neuronavigated

TBS

over

primary

somatosensory

cortex

-LRB-

SI

-RRB-

on

laser-evoked

potentials

-LRB-

LEPs

-RRB-

and

acute

pain

perception

induced

with

Tm

YAG

laser

stimulation

The

amplitude

changes

of

the

and

components

of

LEPs

and

related

subjective

pain

rating

scores

of

healthy

subjects

were

analyzed

prior

to

and

following

continuous

TBS

-LRB-

cTBS

-RRB-

intermittent

TBS

-LRB-

iTBS

-RRB-

intermediate

TBS

-LRB-

imTBS

-RRB-

and

sham

stimulation

Our

results

demonstrate

that

all

active

TBS

paradigms

significantly

diminished

the

amplitude

of

the

component

when

the

hand

contralateral

to

the

site

of

TBS

was

laser-stimulated

Sham

stimulation

condition

had

no

significant

effect

The

subjective

pain

perception

also

decreased

during

the

experimental

sessions

but

did

not

differ

significantly

from

the

sham

stimulation

condition

The

main

finding

of

our

study

is

that

TBS

over

SI

diminished

the

amplitude

of

the

component

evoked

from

the

contralateral

side

without

any

significant

analgesic

effects

Furthermore

imTBS

produced

responses

similar

to

those

observed

by

other

forms

of

TBS

induced

excitability

changes

in

the

SI

Introduction

Functional

neuroimaging

studies

have

provided

unequivocal

evidence

of

the

participation

of

the

primary

somatosensory

cortex

-LRB-

SI

-RRB-

secondary

somatosensory

cortex

-LRB-

SII

-RRB-

and

insula

in

pain

processing

-LRB-

Talbot

et

al.

Casey

et

al.

Apkarian

et

al.

Gelnar

et

al.

-RRB-

Evidence

suggests

that

the

nociceptive

input

into

these

regions

at

least

partially

underlies

the

perception

of

sensory

features

of

pain

-LRB-

Bushnell

et

al.

Coghill

et

al.

Peyron

et

al.

Chen

et

al.

for

a

reviews

see

Peyron

et

al.

Apkarian

et

al.

-RRB-

Electrophysiological

studies

have

also

confirmed

the

participation

of

the

SI

in

pain

processing

contralateral

to

the

stimulated

side

Tarkka

and

Treede

-LRB-

-RRB-

first

reported

pain

induced-activity

in

the

SI

using

electroencephalogram

-LRB-

EEG

-RRB-

and

applying

brain

electric

source

analysis

-LRB-

BESA

-RRB-

In

their

model

the

peak

latency

measured

at

the

SI

was

very

similar

to

that

of

SII

In

a

combined

magnetoencephalogramm

-LRB-

MEG

-RRB-

and

laser-evoked

potential

-LRB-

LEP

-RRB-

study

Ploner

et

al.

-LRB-

-RRB-

reported

SI

activity

also

contralateral

to

the

side

of

stimulation

and

further

to

this

proposed

a

parallel

pain

processing

in

SI

and

SII

This

parallel

activation

of

SI

and

SII

was

confirmed

by

other

studies

-LRB-

Ploner

et

al.

-RRB-

and

other

groups

-LRB-

Timmermann

et

al.

Kanda

et

al.

Inui

et

al.

Nakata

et

al.

-RRB-

However

some

previous

LEP

dipole

modelling

studies

showed

that

a

dipole

source

in

SI

area

was

necessary

to

explain

the

scalp

LEP

topography

of

them

reported

a

clear

correspondence

between

the

SI

activity

and

a

definite

LEP

component

-LRB-

Tarkka

and

Treede

Ploner

et

al.

Kanda

et

al.

-RRB-

Kanda

et

al.

-LRB-

-RRB-

detected

SI

activity

following

painful

stimulation

by

recording

intracranial

EEG

but

recently

intracerebral

depth

recordings

in

an

epileptic

patient

have

shown

no

reliable

LEP

response

from

the

area

of

the

SI

after

painful

laser

stimulation

although

a

reliable

response

could

be

recorded

at

Cz

-LRB-

Valeriani

et

al.

-RRB-

Inui

et

al.

-LRB-

-RRB-

reported

the

absence

of

activation

from

area

of

the

SI

after

noxious

electrical

stimulation

as

well

however

they

found

activity

in

the

area

of

SI

Other

studies

found

no

pain-related

activation

of

the

SI

at

all

-LRB-

for

a

review

see

Garcia-Larrea

et

al.

Kakigi

et

al.

-RRB-

Recent

studies

showed

that

several

kinds

of

external

stimulation

methods

such

as

single-pulse

transcranial

magnetic

stimulation

-LRB-

TMS

-RRB-

-LRB-

Kujirai

et

al.

-RRB-

Hz

repetitive

TMS

-LRB-

rTMS

-RRB-

-LRB-

Enomoto

et

al.

-RRB-

paired

associative

stimulation

-LRB-

PAS

-RRB-

-LRB-

Tsuji

and

Rothwell

Wolters

et

al.

-RRB-

transcranial

direct

current

stimulation

-LRB-

tDCS

-RRB-

-LRB-

Matsunaga

et

al.

Dieckhofer

et

al.

-RRB-

or

theta

burst

stimulation

-LRB-

TBS

-RRB-

-LRB-

Ishikawa

et

al.

-RRB-

modulate

the

amplitude

of

cortical

components

of

median

nerve

somatosensory

evoked

potentials

-LRB-

SEPs

-RRB-

It

was

recently

reported

that

cathodal

tDCS

over

the

SI

-LRB-

Dieckhofer

et

al.

-RRB-

significantly

reduced

the

amplitude

of

median

nerve

SEPs

Furthermore

cathodal

polarization

over

the

SI

induced

a

prolonged

decrease

of

tactile

discrimination

-LRB-

Rogalewski

et

al.

-RRB-

and

diminished

acute

pain

perception

and

the

amplitude

of

the

component

of

LEPs

-LRB-

Antal

et

al.

-RRB-

Recently

Huang

et

al.

-LRB-

-RRB-

developed

a

special

theta

burst

paradigm

to

modulate

human

motor

cortex

-LRB-

-RRB-

excitability

using

low

intensity

repetitive

bursts

of

magnetic

stimuli

The

authors

distinguished

three

stimulation

patterns

which

were

proved

to

have

different

effects

over

activity

when

it

was

monitored

by

the

amplitude

of

transcranial

motor

evoked

potentials

-LRB-

MEPs

-RRB-

Continuous

TBS

-LRB-

cTBS

-RRB-

caused

a

significant

reduction

in

MEP

amplitudes

which

was

probably

due

to

the

inhibition

of

specific

excitatory

circuits

-LRB-

inputs

to

corticospinal

neurons

-RRB-

as

later

confirmed

by

another

study

-LRB-

Di

Lazzaro

et

al.

-RRB-

In

contrast

intermittent

TBS

-LRB-

iTBS

-RRB-

facilitated

activity

and

produced

increase

in

MEP

amplitudes

Interestingly

intermediate

TBS

-LRB-

imTBS

-RRB-

had

no

effect

at

all

In

addition

TBS

has

also

been

shown

to

have

an

effect

on

the

human

premotor

-LRB-

Mochizuki

et

al.

-RRB-

and

visual

cortex

-LRB-

Franca

et

al.

-RRB-

Non-invasive

cortical

stimulation

of

for

the

treatment

of

certain

kinds

of

chronic

and

experimentally

induced

pain

has

recently

attracted

much

interest

Both

low

and

high

frequency

rTMS

was

reported

to

reduce

subjective

pain

perception

and

has

been

used

experimentally

to

reduce

chronic

pain

-LRB-

for

reviews

see

Leo

and

Latif

Fregni

et

al.

-RRB-

However

although

the

involvement

of

SI

in

pain

perception

and

processing

is

reported

by

several

imaging

studies

-LRB-

for

reviews

see

Peyron

et

al.

Apkarian

et

al.

-RRB-

the

magnetic

stimulation

of

this

cortical

area

in

order

to

modify

pain

perception

is

neglected

Therefore

the

aim

of

our

study

was

to

investigate

the

effects

of

cTBS

iTBS

and

imTBS

on

the

early

-LRB-

-RRB-

and

late

-LRB-

-RRB-

components

of

LEPs

and

related

subjective

pain

perception

when

applied

over

the

left

SI

We

hypothesized

that

the

three

TBS

types

which

have

short

durations

-LRB-

maximum

s

-RRB-

would

affect

LEP

components

in

a

specific

paradigm-dependent

manner

similarly

to

the

effect

over

as

revealed

by

Huang

and

et

al.

-LRB-

-RRB-

Methods

Subjects

Nineteen

healthy

volunteers

between

and

years

were

informed

about

all

aspects

of

the

experiments

and

signed

an

informed

consent

Three

subjects

chose

not

to

continue

the

experiment

after

the

first

or

second

session

and

during

off-line

EEG

analysis

four

further

subjects

were

dropped

out

because

of

their

hardly

detectable

LEP

components

Hence

twelve

of

the

subjects

-LRB-

six

male

six

female

mean

age

years

-RRB-

were

included

in

the

final

analysis

We

conformed

with

the

Declaration

of

Helsinki

and

the

experimental

protocol

was

approved

by

the

Ethics

Committee

of

the

University

of

Göttingen

of

the

subjects

suffered

from

chronic

pain

syndromes

nor

took

any

medication

regularly

had

a

history

of

neurological

or

psychiatric

illness

All

of

them

participated

in

all

four

sessions

the

three

TBS

and

sham

stimulations

TBS

stimulation

Theta

burst

stimulation

was

applied

over

the

hand

area

of

the

left

SI

using

a

standard

figure-of-eight-coil

-LRB-

Butterfly

Coil

-RRB-

and

MagPro

stimulator

-LRB-

Medtronic

Denmark

-RRB-

with

an

outer

half-coil

radius

of

mm

with

a

posterior

anterior

posterior

current

flow

in

the

coil

Stimulus

intensity

was

of

active

motor

threshold

-LRB-

AMT

-RRB-

-LRB-

Huang

et

al.

-RRB-

For

AMT

determination

the

coil

was

placed

tangentially

to

the

scalp

with

the

handle

pointing

backwards

and

laterally

from

mid-line

MEPs

of

the

right

abductor

digiti

minimi

muscle

-LRB-

ADM

-RRB-

were

recorded

by

Ag-AgCl-electrodes

in

a

belly

tendon-montage

before

each

stimulation

The

signals

were

amplified

and

filtered

-LRB-

kHz

sampling

rate

of

kHz

-RRB-

digitalized

with

a

micro

AD

converter

-LRB-

Cambridge

Electronic

Design

Cambridge

UK

-RRB-

recorded

by

a

computer

using

SIGNAL

software

-LRB-

Cambridge

Electronic

Design

Version

-RRB-

Complete

muscle

relaxation

was

controlled

though

auditory

and

visual

feedback

of

EMG

activity

AMT

was

defined

as

the

minimum

intensity

eliciting

a

MEP

of

a

superior

size

when

compared

to

spontaneous

moderate

muscular

activity

in

at

least

three

of

six

pulses

The

pattern

of

TBS

consisted

of

bursts

containing

three

pulses

at

Hz

which

were

repeated

at

ms

intervals

-LRB-

i.e.

Hz

-RRB-

for

up

to

pulses

for

s

continuously

-LRB-

cTBS

-RRB-

or

triads

repeated

at

ms

intervals

for

s

intermittently

with

s

breaks

for

up

to

pulses

-LRB-

iTBS

-RRB-

In

the

case

of

imTBS

the

triads

-LRB-

three

pulses

at

Hz

-RRB-

were

repeated

at

ms

intervals

for

s

in

every

s

up

to

pulses

-LRB-

Huang

et

al.

-RRB-

In

separate

experimental

sessions

sham

stimulation

was

applied

with

the

cTBS

protocol

using

the

same

coil

held

over

the

same

position

but

tilted

to

a

angle

-LRB-

one-wing

-RRB-

-LRB-

Lisanby

et

al.

-RRB-

with

only

the

margin

of

the

coil

in

contact

with

the

scalp

Determination

of

the

primary

somatosensory

cortex

-LRB-

SI

-RRB-

Anatomical

magnetic

resonance

imaging

-LRB-

MRI

-RRB-

-LRB-

Siemens

T

weighted

-RRB-

dataset

was

used

to

determinate

the

coil

localization

for

the

stimulation

of

SI

for

all

subjects

using

the

Brainsight

neuronavigation

system

-LRB-

Rogue

Research

Inc.

Montreal

Quebec

Canada

-RRB-

The

hand

area

was

determined

by

previous

fMRI

studies

-LRB-

Bushnell

et

al.

Blankenburg

et

al.

-RRB-

and

was

located

and

marked

in

the

MRI

dataset

as

the

target

for

TMS

application

-LRB-

Fig.

-RRB-

Fig.

dimensional

anatomical

MRI

of

a

single

subject

Anatomical

magnetic

resonance

imaging

-LRB-

MRI

-RRB-

-LRB-

Siemens

T

weighted

-RRB-

dataset

was

used

to

determinate

the

coil

localization

for

the

stimulation

of

SI

by

all

subjects

using

the

Brainsight

neuronavigation

system

The

hand

area

was

located

and

marked

in

the

MRI

dataset

as

target

for

TMS

application

The

black

point

indicates

the

hot-spot

of

the

stimulation

coil

Laser

stimulation

A

Tm

YAG

laser

system

-LRB-

WaveLight

Laser

Technologie

AG

Erlangen

Germany

-RRB-

was

used

to

induce

painful

stimulation

The

thulium

laser

emits

near-infrared

radiation

-LRB-

wavelength

nm

pulse

duration

ms

laser

beam

diameter

mm

-RRB-

with

a

penetration

depth

of

μm

into

the

human

skin

and

allows

a

precise

restriction

of

the

emitted

heat

energy

to

the

termination

area

of

primary

nociceptive

afferents

without

affecting

the

subcutaneous

tissue

-LRB-

Treede

et

al.

-RRB-

The

distal

handpiece

of

the

laser

was

positioned

cm

from

the

radial

part

of

the

dorsal

surface

of

the

hand

The

pain

threshold

was

determined

on

both

hands

at

the

beginning

each

session

before

baseline

EEG

recording

by

applying

laser

stimuli

from

mJ

in

mJ

steps

During

EEG

recordings

each

laser

stimulus

was

delivered

with

an

intensity

of

times

the

threshold

intensity

to

a

slightly

different

spot

in

a

cm

square

on

the

dorsum

of

the

hand

in

order

to

reduce

receptor

fatigue

or

sensitization

by

skin

overheating

-LRB-

Treede

et

al.

-RRB-

Skin

temperature

of

the

stimulated

area

was

checked

prior

to

every

switch

between

hands

and

corrected

with

a

heating

lamp

if

it

fell

below

°C

Psychophysical

evaluation

We

used

the

verbal

analogue

score

-LRB-

VAS

-RRB-

to

assess

the

subjective

intensity

of

pain

The

subjects

were

instructed

to

pay

attention

to

the

laser

stimuli

and

to

rate

the

perceived

pain

verbally

-LRB-

smallest

pain

and

most

intense

pain

-RRB-

about

s

after

each

laser-impulse

The

values

were

individually

averaged

separately

for

both

hands

in

each

session

and

conditions

The

ears

of

the

subjects

were

plugged

during

the

measurements

to

avoid

auditory

artifacts

accompanying

laser

stimulation

Electrophysiological

recordings

The

EEG

was

recorded

using

a

montage

applying

ring

electrodes

-LRB-

inner

diameter

mm

outer

diameter

mm

-RRB-

-LRB-

EasyCap

Falk

and

Minow

GmbH

Münich

Germany

-RRB-

The

electrodes

were

placed

in

accordance

with

the

extended

international

system

The

impedance

was

kept

kΩ

The

Fz

was

used

as

reference

the

ground

was

placed

cm

anterior

to

the

tragus

of

the

right

ear

Data

were

collected

at

a

sampling

rate

of

Hz

with

the

BrainAmp

system

-LRB-

Brain

Products

GmbH

Munich

Germany

-RRB-

and

were

analyzed

offline

The

obtained

data

were

re-referenced

to

the

connected

mastoids

-LRB-

-RRB-

A

Hz

low-cutoff

as

well

as

a

Hz

high-cutoff

filter

was

used

In

addition

to

automatic

artifact

detection

-LRB-

μV

amplitude

criterion

-RRB-

all

epochs

were

visually

inspected

and

those

containing

eye

blinks

or

muscle

movement

artifacts

were

excluded

Baseline

correction

was

performed

on

the

basis

of

the

ms

prestimulus

interval

The

amplitudes

of

-LRB-

referring

to

Fz

-RRB-

and

-LRB-

referring

to

-RRB-

components

were

measured

Although

we

recorded

data

on

channels

we

assessed

LEPs

according

to

the

scalp

distribution

on

the

analyzed

peaks

The

is

a

negative

component

-LRB-

referring

to

-RRB-

was

peaking

around

ms.

The

amplitude

of

the

early

negative

peak

which

came

before

on

and

channels

-LRB-

referring

to

Fz

-RRB-

was

analyzed

The

positive

component

after

was

peaking

around

ms.

The

component

is

largest

over

the

lateral

temporal

and

fronto-central

areas

on

electrodes

Fz

Cz

CPz

and

In

contrast

the

peak

has

its

maximum

amplitude

over

the

vertex

on

electrodes

FCz

Cz

CPz

Pz

and

For

the

analysis

of

LEPs

according

to

regional

distribution

we

defined

three

distinct

areas

with

pooling

the

data

central

-LRB-

with

all

the

mid-line

electrodes

such

as

Fz

FCz

Cz

CPz

and

Pz

-RRB-

left

-LRB-

and

-RRB-

and

right

-LRB-

electrodes

according

to

the

left

side

-RRB-

instead

of

separate

electrodes

Experimental

design

The

subjects

were

sitting

in

a

reclining

chair

In

case

of

all

sessions

first

the

EEG

cap

was

placed

on

the

head

After

pain

threshold

determination

the

baseline

LEP

measurements

were

performed

Every

run

for

the

LEP

recording

consisted

of

epochs

of

laser

stimulation

on

each

hand

The

interstimulus

interval

of

the

stimulation

ranged

from

to

s

-LRB-

Raij

et

al.

-RRB-

Thus

the

LEP

recording

lasted

for

min

for

the

first

hand

and

also

for

min

for

the

second

hand

laser-stimulation

In

all

three

TBS

and

sham

TBS

conditions

the

right

hand

was

stimulated

first

in

half

of

the

cases

and

the

left

hand

was

stimulated

first

in

the

other

half

This

order

was

kept

for

the

subjects

for

all

conditions

After

baseline

LEP

recording

the

AMT

was

measured

-LRB-

min

-RRB-

and

the

TBS

were

applied

for

s

through

the

cap

After

TBS

the

impedance

of

the

EEG

electrodes

were

retested

and

corrected

below

kΩ

if

it

was

necessary

The

TBS

was

followed

by

a

post-stimulation

LEP

recording

in

min

after

TBS

Thus

the

interval

between

the

two

LEP

recordings

with

regard

to

the

same

hand

was

about

min

including

all

subjects

and

conditions

The

experimental

sessions

were

separated

from

each

other

by

at

least

days

The

subjects

were

blinded

as

to

the

type

of

magnetic

stimulation

The

order

of

the

sessions

was

randomized

across

subjects

Data

analysis

The

individually

averaged

VAS

values

and

LEP

amplitudes

were

entered

into

a

repeated-measures-ANOVA

for

both

hands

and

LEP

components

separately

-LSB-

four

TBS

CONDITION

-LRB-

cTBS

iTBS

imTBS

and

sham

-RRB-

TIME

-LRB-

before

after

TBS

-RRB-

-RSB-

We

considered

a

psychophysical

or

an

electrophysiological

change

only

if

the

CONDITION

TIME

interaction

was

significant

In

case

of

the

LEP

components

we

investigated

if

this

effect

was

dependent

on

the

defined

areas

by

calculating

the

CONDITION

TIME

REGION

interaction

Post

hoc

analysis

was

done

using

Student

's

t

tests

-LRB-

paired

samples

two-tailed

level

of

significance

P

-RRB-

Results

Psychophysics

The

intensity

of

the

laser

stimulation

-LRB-

of

the

pain

threshold

-RRB-

was

for

cTBS

for

iTBS

for

imTBS

and

for

sham

stimulation

of

the

subjects

reported

any

side-effect

after

the

stimulation

In

case

of

the

contralateral

hand

-LRB-

right

-RRB-

stimulation

repeated-measures-ANOVA

revealed

no

main

effect

of

CONDITION

-LSB-

F

-LRB-

-RRB-

P

-RSB-

but

the

TIME

was

significant

-LSB-

F

-LRB-

-RRB-

P

-RSB-

The

CONDITION

TIME

interaction

was

also

not

significant

-LSB-

F

-LRB-

-RRB-

P

-RSB-

In

case

of

the

ipsilateral

hand

-LRB-

left

-RRB-

stimulation

there

was

no

significant

main

effect

of

CONDITION

-LSB-

F

-LRB-

-RRB-

P

-RSB-

but

the

TIME

was

significant

-LSB-

F

-LRB-

-RRB-

P

-RSB-

The

CONDITION

TIME

interaction

was

also

not

significant

-LSB-

F

-LRB-

-RRB-

P

-RSB-

-LRB-

Fig.

-RRB-

Fig.

effects

of

the

TBS

on

subjective

pain

perception

The

VAS-values

were

standardized

for

each

subject

for

each

condition

by

calculating

the

after/before

ratio

The

independent

variables

were

the

CONDITION

and

HAND

in

order

to

determine

if

there

is

any

difference

between

stimulation

of

the

two

hands

There

was

no

main

effect

of

the

stimulation

CONDITION

and

the

HAND

-LRB-

left

or

right

-RRB-

The

interaction

CONDITION

TIME

was

also

not

significant

Electrophysiology

The

and

components

could

clearly

be

identified

in

all

subjects

The

LEPs

are

presented

in

Figs.

and

Fig.

effects

of

the

TBS

on

the

component

The

figure

shows

amplitude

changes

during

the

experimental

sessions

on

the

grand

averages

of

LEPs

The

was

analyzed

over

the

electrodes

and

referred

to

Fz

-LRB-

international

electrode

system

-RRB-

in

case

of

both

hands

The

solid

line

shows

LEPs

before

and

the

intermittent

line

after

TBS

interventions

There

was

no

significant

difference

between

stimulation

conditionsFig

averages

of

LEPs

obtained

by

contralateral

-LRB-

right

-RRB-

hand

laser

stimulation

for

three

scalp

regions

-LRB-

central

left

and

right

-RRB-

re-referenced

to

the

connected

mastoids

-LRB-

-RRB-

before

and

after

the

three

TBS

conditions

and

sham

stimulation

The

solid

line

shows

LEPs

before

and

the

intermittent

line

after

TBS

interventions

The

component

We

analyzed

the

amplitudes

of

the

early

components

on

channels

and

-LRB-

referring

to

Fz

-RRB-

There

was

no

significant

main

effect

of

CONDITION

-LSB-

contralateral

hand

F

-LRB-

-RRB-

P

ipsilateral

hand

F

-LRB-

-RRB-

P

-RSB-

The

TIME

was

significant

if

the

contralateral

hand

was

stimulated

-LSB-

F

-LRB-

-RRB-

P

-RSB-

but

not

for

the

ipsilateral

hand

-LSB-

F

-LRB-

-RRB-

P

-RSB-

The

interaction

of

the

CONDITION

TIME

resulted

in

no

significant

interaction

neither

after

the

contraleteral

-LSB-

F

-LRB-

-RRB-

P

-RSB-

or

ipsilateral

-LSB-

F

-LRB-

-RRB-

P

-RSB-

hand

stimulation

-LRB-

Fig.

-RRB-

The

component

The

repeated-measures-ANOVA

-LRB-

ipsilateral

hand

-RRB-

showed

no

significant

main

effect

of

CONDITION

-LSB-

F

-LRB-

-RRB-

P

-RSB-

but

the

effect

of

TIME

was

significant

-LSB-

F

-LRB-

-RRB-

P

-RSB-

The

CONDITION

TIME

interaction

resulted

in

no

significance

-LSB-

F

-LRB-

-RRB-

P

-RSB-

-LRB-

Fig.

-RRB-

In

case

of

the

-LRB-

contralateral

hand

-RRB-

the

main

effect

of

CONDITION

-LSB-

F

-LRB-

-RRB-

P

-RSB-

was

not

significant

but

the

TIME

was

significant

-LSB-

F

-LRB-

-RRB-

P

-RSB-

The

CONDITION

TIME

interaction

was

also

significant

-LSB-

F

-LRB-

-RRB-

P

-RSB-

-LRB-

Fig.

-RRB-

The

interaction

with

electrode

position

was

not

significant

-LSB-

F

-LRB-

-RRB-

P

-RSB-

The

post

hoc

t

test

showed

that

all

active

TBS

stimulation

significantly

decreased

the

amplitudes

of

the

component

at

all

defined

regions

for

the

contralateral

hand

stimulation

Table

summarizes

the

results

of

t

tests

Fig.

mean

amplitude

changes

during

the

four

TBS

conditions

at

the

ipsilateral

-LRB-

left

-RRB-

-LRB-

Fig.

-RRB-

and

contralateral

-LRB-

right

-RRB-

-LRB-

Fig.

-RRB-

hand

laser-stimulation

for

the

three

calculated

regions

-LRB-

central

left

and

right

-RRB-

The

stars

mark

significant

differences

between

before-after

TBS

conditions

-LRB-

post

hoc

t-tests

paired

samples

two-tailed

P

-RRB-

Table

hoc

analysis

of

the

componentcTBSiTBSimTBSshamBefore

versus

afterBefore

versus

afterBefore

versus

afterBefore

versus

t-values

t-values

t-values

Shows

the

results

of

the

Student

's

t-tests

-LRB-

paired

samples

two-tailed

-RRB-

in

case

of

the

right

hand

stimulation

The

level

of

the

significance

was

P

The

component

The

repeated-measures-ANOVA

showed

no

significant

main

effect

of

CONDITION

-LSB-

contralateral

F

-LRB-

-RRB-

P

ipsilateral

F

-LRB-

-RRB-

P

-RSB-

but

the

TIME

was

significant

-LSB-

contralateral

F

-LRB-

-RRB-

P

ipsilateral

F

-LRB-

-RRB-

P

-RSB-

The

CONDITION

TIME

interaction

was

also

not

significant

-LSB-

contralateral

F

-LRB-

-RRB-

P

ipsilateral

F

-LRB-

-RRB-

P

-RSB-

The

means

of

the

different

LEP

components

from

all

subjects

are

presented

in

Table

Table

mean

amplitudes

of

the

LEP

componentsPeakcTBSiTBSimTBSshamBeforeAfterBeforeAfterBeforeAfterBeforeAfterLeft

Left

Right

Right

Left

Right

The

mean

amplitudes

of

the

LEP

components

before

and

after

stimulation

in

all

four

conditions

-LRB-

mean

standard

deviation

-RRB-

Discussion

The

main

finding

of

our

study

is

that

all

theta

burst

paradigms

over

the

SI

were

able

to

diminish

the

amplitude

of

the

component

of

LEPs

significantly

when

compared

to

sham

stimulation

Surprisingly

the

imTBS

condition

that

is

suggested

to

be

used

as

a

placebo

condition

when

it

applied

over

the

-LRB-

Huang

et

al.

-RRB-

also

caused

a

strong

amplitude

decrease

The

and

components

and

the

subjective

pain

rating

scores

were

not

significantly

influenced

by

any

type

of

TBS

Recent

studies

using

the

theta

burst

paradigm

have

concentrated

on

the

effects

of

continuous

-LRB-

cTBS

-RRB-

and

intermittent

theta

burst

stimulation

-LRB-

iTBS

-RRB-

-LRB-

Franca

et

al.

Andoh

et

al.

Ishikawa

et

al.

Koch

et

al.

Mochizuki

et

al.

-RRB-

of

them

investigated

the

intermediate

-LRB-

imTBS

-RRB-

pattern

since

Huang

and

et

al.

published

that

it

has

no

effect

over

the

as

revealed

by

MEPs

and

could

thus

be

used

as

a

sham

condition

-LRB-

Huang

et

al.

-RRB-

According

to

our

knowledge

only

five

studies

applied

TBS

over

non-motor

cortical

areas

First

Franca

et

al.

-LRB-

-RRB-

used

the

theta

burst

pattern

of

rTMS

over

the

visual

cortex

They

found

that

cTBS

increased

phosphene

thresholds

whilst

iTBS

was

found

to

be

ineffective

In

another

study

both

cTBS

and

iTBS

over

the

left

dorsal

premotor

cortex

decreased

the

transcallosal

inhibition

revealed

by

pairs

of

transcranial

magnetic

stimuli

-LRB-

Koch

et

al.

-RRB-

In

a

recent

study

Wernicke

's

area

was

stimulated

with

iTBS

while

the

reaction

time

of

auditory

word

detection

was

measured

-LRB-

Andoh

et

al.

-RRB-

In

this

work

iTBS

facilitated

the

detection

of

foreign

words

when

compared

with

native

words

Concerning

the

SI

a

shorter

form

of

the

iTBS

-LRB-

pulses

-RRB-

over

the

left

SI

resulted

in

a

significant

oxy-hemoglobin

decrease

at

the

contralateral

SI

and

detected

by

near

infrared

spectroscopy

-LRB-

Mochizuki

et

al.

-RRB-

In

another

study

cTBS

of

the

SI

resulted

in

a

temporary

decrease

-LRB-

min

-RRB-

whereas

stimulation

of

the

caused

a

long-lasting

increase

-LRB-

up

to

min

-RRB-

of

the

amplitudes

of

cortical

components

of

the

median

nerve

SEPs

-LRB-

Ishikawa

et

al.

-RRB-

In

summary

these

results

suggest

that

cTBS

has

an

inhibitory

effect

on

non-motor

areas

whereas

the

effect

of

iTBS

is

more

facilitatory

but

clearer

results

have

still

to

emerge

Our

results

are

the

first

demonstrating

that

all

three

TBS

paradigms

but

not

by

sham

stimulation

over

the

SI

resulted

in

similar

after-effects

regarding

the

amplitude

of

the

component

of

LEPs

evoked

by

the

laser

stimulation

of

the

contralateral

hand

The

component

-LRB-

peaking

around

ms

-RRB-

is

generated

bilaterally

in

the

operculoinsular

region

and

in

the

anterior

cingulate

cortex

-LRB-

ACC

-RRB-

-LRB-

Garcia-Larrea

et

al.

-RRB-

and

reflects

sensory

discriminatory

processes

-LRB-

Garcia-Larrea

et

al.

Iannetti

et

al.

-RRB-

whilst

the

component

-LRB-

peaking

around

ms

-RRB-

arose

mostly

from

the

ACC

and

represents

attentional

cognitive

and

affective

factors

of

pain

perception

and

processing

-LRB-

Treede

-RRB-

However

other

studies

did

not

find

significantly

different

brain

sources

for

and

revealing

both

parasylvian

and

ACC

contributions

for

the

components

-LRB-

Raij

et

al.

Ohara

et

al.

-RRB-

Thus

LEP

changes

in

or

component

might

result

from

changes

in

either

sensory-discriminative

or

cognitive

aspects

of

pain

Studies

using

subdural

recordings

-LRB-

Kanda

et

al.

Ohara

et

al.

-RRB-

or

MEG

-LRB-

Kanda

et

al.

-RRB-

demonstrated

that

the

LEP

components

can

be

recorded

over

the

SI

and

SII

simultaneously

and

the

peak

may

indicate

the

arrival

of

input

originating

from

nociceptors

With

regard

to

the

component

which

is

an

early

LEP

potential

-LRB-

peaking

around

ms

-RRB-

and

reflecting

the

early

sensory-discriminative

processing

of

pain

perception

-LRB-

Iannetti

et

al.

-RRB-

we

did

not

find

any

significant

change

in

amplitude

According

to

scalp

topography

-LRB-

maximum

near

and

-RRB-

the

is

generated

near

to

the

SII

in

the

fronto-parietal

operculum

-LRB-

Treede

et

al.

-RRB-

The

participation

of

operculoinsular

cortex

in

coding

the

pain

intensity

was

recently

suggested

by

using

LEP

measurements

-LRB-

Ianetti

et

al.

-RRB-

However

another

study

-LRB-

Gracia-Larrea

et

al.

-RRB-

did

not

find

any

significant

correlation

between

the

amplitude

of

the

component

and

subjective

pain

rating

The

fact

that

we

found

a

decrement

of

both

the

and

amplitudes

in

the

sham

condition

as

well

should

be

discussed

This

phenomenon

is

known

as

habituation

and

has

been

described

in

previous

LEP

studies

-LRB-

Spiegel

et

al.

Tamura

et

al.

-RRB-

Still

the

effects

of

real

TBS

conditions

on

amplitudes

were

greater

than

that

of

the

sham

condition

and

it

was

significant

above

the

stimulated

left

the

neighboring

central

and

the

contralateral

area

as

well

when

the

right

hand

was

laser

stimulated

Attention

can

also

directly

influence

the

components

of

LEPs

as

well

as

subjective

pain

rating

as

it

was

suggested

by

previous

experimental

results

-LRB-

Gracia-Larrea

et

al.

Ohara

et

al.

-RRB-

In

our

experiment

the

subjects

were

asked

to

pay

attention

to

each

laser

stimuli

and

since

the

TBS

and

sham

condition

were

applied

in

a

randomized

order

and

the

subjects

were

blinded

as

to

the

type

of

magnetic

stimulation

the

significant

difference

between

sham

and

the

other

three

TBS

on

the

amplitude

is

more

than

simply

habituation

or

the

effect

of

the

different

attentional

states

The

possible

origin

of

the

component

is

mainly

the

bilateral

operculoinsular

region

and

the

ACC

-LRB-

Garcia-Larrea

et

al.

-RRB-

Therefore

when

we

inhibited

the

left

SI

the

activity

of

the

pain

related

cortical

network

decreased

due

to

the

widespread

cortical

connections

between

SI

and

other

cortical

areas

However

the

involvement

of

the

contralateral

SI

and

bilateral

SII

parasylvian

region

in

the

component

generation

was

also

reported

-LRB-

Kakigi

et

al.

Kanda

et

al.

Ohara

et

al.

-RRB-

According

to

this

it

is

also

possible

that

the

inhibition

of

the

SI

itself

may

cause

direct

effects

on

LEP

components

In

this

study

we

found

no

significant

difference

between

the

stimulation

conditions

with

regard

to

subjective

pain

perception

-LRB-

Fig.

-RRB-

however

the

subjective

pain

rating

decreased

during

the

experimental

sessions

after

every

type

of

TBS

including

the

sham

condition

It

is

important

to

mention

that

the

placebo

effect

is

high

in

almost

every

pain

perception

study

regardless

of

the

paradigm

used

-LRB-

Khedr

et

al.

Lefaucheur

et

al.

-RRB-

The

explanation

of

this

discrepancy

between

the

electrophysiological

and

psychophysical

changes

is

rather

speculative

because

the

relationship

between

the

anatomical

origin

of

the

components

and

their

psychophysical

correlates

controversially

discussed

in

the

literature

In

a

PET

study

different

cortical

activations

for

pain

threshold

intensity

and

unpleasantness

have

been

found

-LRB-

Tölle

et

al.

-RRB-

One

possibility

is

that

modulation

the

excitability

of

the

left

SI

by

TBS

activated

some

elements

of

the

pain

related

network

that

caused

a

decrease

in

the

amplitude

However

this

stimulation

intensity

or

duration

was

not

strong

or

adequate

enough

to

modify

the

subjective

pain

rating

In

our

previous

study

-LRB-

Antal

et

al.

-RRB-

we

found

that

cathodal

tDCS

over

the

SI

similarly

to

the

present

findings

significantly

decreased

the

component

of

LEPs

In

contrast

to

the

present

findings

the

subjective

pain

perception

in

healthy

subjects

was

also

diminished

TDCS

is

a

method

that

modifies

the

resting

membrane

potentials

of

cortical

neurons

intracortically

-LRB-

Nitsche

and

Paulus

-RRB-

Cathodal

stimulation

decreases

whilst

anodal

stimulation

increases

cortical

excitability

-LRB-

Nitsche

and

Paulus

-RRB-

However

in

that

study

we

have

used

a

large

electrode

size

-LRB-

cm

-RRB-

in

order

to

optimize

stimulation

's

parameters

-LRB-

Nitsche

and

Paulus

-RRB-

and

therefore

we

might

have

covered

a

large

part

of

the

SI

It

is

possible

that

we

have

stimulated

one

part

of

the

somatosensory

association

cortex

-LRB-

BA

-RRB-

that

is

posterior

to

the

SI

Activation

of

human

has

also

been

linked

to

pain

perception

-LRB-

Apkarian

et

al.

Forss

et

al.

-RRB-

BA

is

anatomically

connected

to

other

nociceptive

brain

areas

such

as

the

ACC

insula

thalamus

and

primary

motor

cortices

-LRB-

Friedman

et

al.

-RRB-

In

order

to

increase

the

focality

of

the

transcranial

stimulation

in

the

present

study

we

used

a

neuronavigation

system

to

determine

the

hand

area

over

the

SI

Many

of

the

previous

pain-related

studies

stimulated

the

The

effects

of

low

and

high

frequency

rTMS

of

on

experimentally

induced

acute

pain

perception

seem

to

depend

on

the

type

of

noxious

stimulation

C-fiber

mediated

acute

pain

as

induced

by

intradermal

capsaicin

administration

could

be

attenuated

by

Hz

rTMS

over

the

-LRB-

Tamura

et

al.

-RRB-

whereas

it

increased

Aδ-fiber

mediated

laser-induced

pain

in

another

study

-LRB-

Tamura

et

al.

-RRB-

Similarly

controversial

effects

were

observed

after

Hz

rTMS

-LRB-

Johnson

et

al.

Summers

et

al.

-RRB-

In

contrast

Hz

rTMS

over

increased

electrically

induced

Aδ-fiber

mediated

pain

threshold

-LRB-

Yoo

et

al.

-RRB-

but

others

found

that

Hz

rTMS

has

only

an

effect

on

the

unpleasantness

of

the

pain

without

any

effect

on

pain

threshold

-LRB-

Mylius

et

al.

-RRB-

In

case

of

chronic

pain

the

high

frequency

rTMS

seems

to

more

effective

than

the

application

of

low

frequencies

-LRB-

Leo

and

Latif

-RRB-

The

neuronal

mechanism

of

the

theta

burst

paradigm

is

highly

speculative

The

results

of

the

experiments

with

single

trains

of

TBS

suggest

that

in

the

human

TBS

produces

a

mixture

of

facilitatory

and

inhibitory

effects

on

synaptic

transmission

-LRB-

Huang

and

Rothwell

-RRB-

Huang

and

Rothwell

proposed

that

facilitation

develops

faster

than

inhibition

thus

in

case

of

the

inhibitory

cTBS

several

seconds

after

an

initial

facilitation

the

inhibition

overrides

this

effect

ITBS

uses

only

the

early

excitatory

effect

in

the

initial

s

and

after

this

the

stimulation

is

interrupted

for

s.

Most

likely

the

underlying

mechanisms

will

involve

many

of

the

basic

elementary

mechanisms

described

previously

in

the

LTP/LTD

literature

-LRB-

Paulus

-RRB-

Recently

Huang

et

al.

-LRB-

-RRB-

have

demonstrated

that

the

after-effects

produced

by

both

iTBS

or

cTBS

are

NMDA-receptor

dependent

and

hence

they

are

more

likely

to

involve

plasticity-like

changes

at

the

synapse

in

the

More

recently

it

was

found

that

the

excitatory

effects

of

iTBS

were

reversed

after

NMDA

receptor

activation

by

D-cycloserin

-LRB-

Teo

et

al.

-RRB-

This

is

in

contrast

with

the

findings

of

tDCS

induced

LTP

where

the

excitatory

effects

are

prolonged

by

D-cycloserin

-LRB-

Nitsche

et

al.

-RRB-

However

it

is

important

to

note

that

these

observations

were

done

on

the

It

is

possible

that

the

different

effectiveness

observed

between

TBS

protocols

on

motor

and

sensory

cortices

could

be

due

to

differences

in

the

physiological

and

functional

states

of

the

stimulated

cortex

In

summary

in

our

study

we

found

a

significant

decrease

of

the

component

of

the

LEPs

after

cTBS

iTBS

and

imTBS

when

compared

to

sham

stimulation

over

the

SI

In

addition

we

found

that

the

subjective

pain

perception

did

not

show

significant

differences

among

the

stimulation

conditions

suggesting

that

this

method

is

probably

not

the

most

effective

in

decreasing

subjective

pain

perception

Further

findings

show

that

imTBS

resulted

in

more

impressive

modification

of

the

LEPs

than

were

found

in

previous

TMS-studies

over

the

using

MEP

measures

-LRB-

Huang

et

al.

-RRB-

implying

that

it

should

not

be

used

in

further

studies

as

sham

condition

at

least

with

regard

to

LEPs

and

when

it

is

applied

over

the

SI

However

these

results

are

not

directly

comparable

with

the

effects

of

TBS

on

thus

further

studies

are

needed

to

clarify

the

effects

of

imTBS

on

different

cortical

areas

Future

studies

should

also

clarify

the

effectiveness

of

the

different

TBS

paradigms

applied

over

the

and

non-motor

cortical

areas

such

as

the

SII

on

acute

pain

perception

and

in

chronic

pain

O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B O O O O O O B O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O B O

primary somatosensory cortex
pain
neuronavigation

theta burst transcranial magnetic stimulation