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Consciousness in the Human Brain - Maastricht University

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<strong>Consciousness</strong> <strong>in</strong> <strong>the</strong> <strong>Human</strong> Bra<strong>in</strong><br />

Tom de Graaf<br />

Dept of Cognitive Neuroscience,<br />

Faculty of Psychology & Neuroscience, <strong>Maastricht</strong> <strong>University</strong><br />

(from De motu animalium, 4th century B.C.)<br />

The seat of <strong>the</strong> soul …- <strong>in</strong> fact, of nervous functions <strong>in</strong><br />

general, - is to be sought <strong>in</strong> <strong>the</strong> heart. The bra<strong>in</strong> is an<br />

organ of m<strong>in</strong>or importance.<br />

And of course, <strong>the</strong> bra<strong>in</strong> is not responsible for any of<br />

<strong>the</strong> sensations at all. The correct view is that <strong>the</strong> seat<br />

and source of sensation is <strong>the</strong> region of <strong>the</strong> heart.


Aristotle<br />

16th century science:<br />

Kallionates & Luu, 2005<br />

Aristotle<br />

Galen


Galen<br />

• What is necessary for<br />

consciousness?<br />

• Press <strong>the</strong> Heart<br />

• Cut <strong>the</strong> Bra<strong>in</strong><br />

<strong>Consciousness</strong> <strong>in</strong> <strong>the</strong> bra<strong>in</strong>?<br />

Feel<strong>in</strong>g<br />

Taste/smell<br />

See<strong>in</strong>g<br />

Hear<strong>in</strong>g


<strong>Consciousness</strong> <strong>in</strong> <strong>the</strong> bra<strong>in</strong>?<br />

The visual system:<br />

some of its parts and connections<br />

Felleman & Essen (1991), Cerebral cortex


Pre-consciousness<br />

consciousness:<br />

• What IS consciousness?<br />

• HUMAN consciousness studies<br />

• Research paradigms<br />

F<strong>in</strong>d<strong>in</strong>gs:<br />

• Neural Correlates of Unconsciousness<br />

• Neural Correlates of <strong>Consciousness</strong><br />

Manipulat<strong>in</strong>g <strong>Consciousness</strong> (TMS)<br />

<strong>Consciousness</strong> research at our university<br />

What IS consciousness?<br />

Self awareness<br />

“<strong>Consciousness</strong>”<br />

Higher-order awareness<br />

Medical awareness<br />

Experience<br />

Access consciousness<br />

Phenomenal consciousness<br />

HARD PROBLEM ?<br />

De Graaf et al (<strong>in</strong> preparation)


What are <strong>the</strong> problems?<br />

• Color chang<strong>in</strong>g card trick<br />

• Bl<strong>in</strong>dsight<br />

• Many different k<strong>in</strong>ds of problems, , we focus<br />

on conscious vs unconscious vision


What are <strong>the</strong> problems?<br />

• Color chang<strong>in</strong>g card trick<br />

• Bl<strong>in</strong>dsight<br />

• Many different k<strong>in</strong>ds of problems, , we focus<br />

on conscious vs unconscious vision


Watch<strong>in</strong>g <strong>the</strong> Conscious Bra<strong>in</strong><br />

• Functional<br />

Magnetic<br />

Resonance<br />

Imag<strong>in</strong>g<br />

(fMRI)<br />

3T MRI scanner, at FPN <strong>in</strong> <strong>Maastricht</strong><br />

• What is happen<strong>in</strong>g<br />

<strong>in</strong>side <strong>the</strong> bra<strong>in</strong>?<br />

• Regional bra<strong>in</strong><br />

activity<br />

What’s fMRI?<br />

FMRI allows <strong>the</strong> time course<br />

of human bra<strong>in</strong> activity to be<br />

imaged.<br />

With fMRI it is possible to<br />

study not only what <strong>the</strong><br />

bra<strong>in</strong> looks like, but also<br />

how <strong>the</strong> bra<strong>in</strong> works when<br />

<strong>the</strong> subject is look<strong>in</strong>g at<br />

images, listen<strong>in</strong>g to<br />

sounds, imag<strong>in</strong><strong>in</strong>g<br />

someth<strong>in</strong>g etc.


An easy example of an fMRI experiment<br />

V5<br />

V1 / V2<br />

Activity <strong>in</strong> <strong>the</strong> bra<strong>in</strong><br />

MFG<br />

SPL<br />

SPL<br />

MFG<br />

OC<br />

OC<br />

De Graaf et al., 2009, JOCN


What has been “imaged”<br />

• How much we like to pay taxes<br />

• Political preference of undecided voters <strong>in</strong><br />

<strong>the</strong> ’08 US presidential election<br />

• Romantic love<br />

• Erotic love<br />

• Moral <strong>in</strong>cl<strong>in</strong>ations<br />

• M<strong>in</strong>d-read<strong>in</strong>g<br />

(we’ll<br />

see this later)<br />

Network function <strong>in</strong> <strong>the</strong> bra<strong>in</strong><br />

Functional connectivity:<br />

areas work<strong>in</strong>g toge<strong>the</strong>r (when you look at <strong>the</strong> clock)<br />

De Graaf et al., 2009, JOCN


Information Flow <strong>in</strong> <strong>the</strong> Bra<strong>in</strong><br />

A B C<br />

effective<br />

connectivity<br />

activity<br />

time<br />

A<br />

C<br />

B<br />

A<br />

A<br />

De Graaf et al., 2009, JOCN<br />

Individual GCM <strong>in</strong> volume space<br />

suggests neighbor<strong>in</strong>g clusters<br />

differentially connected to PPC<br />

and o<strong>the</strong>r network nodes.<br />

Might be a form of recurrent loops<br />

Hypo<strong>the</strong>sized model<br />

De Graaf et al., 2009, JOCN


Bra<strong>in</strong> Systems of Visual<br />

<strong>Consciousness</strong><br />

Tom A. de Graaf, FdP, <strong>Maastricht</strong> <strong>University</strong> 20/03/08 TopTalent<br />

Separat<strong>in</strong>g Conscious from<br />

Unconscious Vision<br />

Conscious:<br />

Blue, p<strong>in</strong>k, orange, pretty, “I<br />

feel all warm and glowy… ”<br />

Unconscious:<br />

Wavelengths,<br />

contrasts,<br />

associations: “what<br />

<strong>the</strong> hell am I do<strong>in</strong>g<br />

here?”


Separat<strong>in</strong>g Conscious from<br />

Unconscious Vision<br />

Conscious: “apple-ness”<br />

Unconscious: : 650 nm, shape,<br />

orientations<br />

Conscious: “pear-ness”<br />

Unconscious: : 510 nm,<br />

shape, orientations<br />

Separat<strong>in</strong>g Conscious from<br />

Unconscious Vision<br />

Conscious:<br />

Blue, p<strong>in</strong>k, orange, pretty, “I<br />

feel all warm and glowy… ”<br />

Unconscious:<br />

Wavelengths,<br />

contrasts,<br />

associations: “what<br />

<strong>the</strong> hell am I do<strong>in</strong>g<br />

here?”


Ways to separate conscious vision<br />

from unconscious vision<br />

• Change <strong>the</strong> conscious experience, , keep<br />

constant <strong>the</strong> <strong>in</strong>com<strong>in</strong>g stimulation<br />

• Conscious Vision<br />

• Change <strong>the</strong> <strong>in</strong>com<strong>in</strong>g stimulation, , keep<br />

constant <strong>the</strong> conscious experience<br />

• Unconscious Vision<br />

Illusions<br />

Illusory brightness,<br />

size, contours<br />

Halluc<strong>in</strong>ations etc.<br />

Multistable Perception<br />

B<strong>in</strong>ocular rivalry<br />

(monocular rivalry)<br />

(pattern rivalry)<br />

Ambiguous stimuli<br />

Research Paradigms<br />

for NCC and NCU<br />

ON-OFF paradigm<br />

OFF-basel<strong>in</strong>e<br />

Strong ON-OFF<br />

(perception depends on<br />

background variables)<br />

Weak ON-OFF<br />

(experimenter determ<strong>in</strong>es<br />

perception by experimental<br />

manipulation)<br />

Cont<strong>in</strong>uous flash suppression<br />

De Graaf et al (<strong>in</strong> preparation)


What do you see?<br />

What do you see?


What do you see?<br />

What do you see?


What do you see?<br />

What do you see?


What do you see?<br />

What do you see?


Exercise<br />

A = B ?<br />

Exercise<br />

A = B ?<br />

http://www.youtube.com/watch?v=QirAG58U1FY


<strong>Consciousness</strong> <strong>in</strong> <strong>the</strong> bra<strong>in</strong>?<br />

Feel<strong>in</strong>g<br />

Taste/smell<br />

See<strong>in</strong>g<br />

Hear<strong>in</strong>g<br />

One bra<strong>in</strong> experiment<br />

Cell 1 fires if someth<strong>in</strong>g passes through here<br />

Cell 2 fires if someth<strong>in</strong>g passes through here<br />

High<br />

Waves<br />

Some<br />

Waves<br />

The higher <strong>the</strong> waves are, <strong>the</strong> more<br />

cell 1 and cell 2 communicate<br />

Someth<strong>in</strong>g OUTSIDE of <strong>the</strong>se cells<br />

<strong>in</strong>fluences how <strong>the</strong>y fire and<br />

communicate:<br />

Someth<strong>in</strong>g that determ<strong>in</strong>es whe<strong>the</strong>r <strong>the</strong><br />

bars are part of one object or not. Gray et al., Science, 1989<br />

No<br />

Waves


Ano<strong>the</strong>r bra<strong>in</strong> experiment<br />

A: real contour<br />

B: illusory contour<br />

C: no contour<br />

Von der Heydt, Science, 1984<br />

Ano<strong>the</strong>r bra<strong>in</strong> experiment<br />

Neurons <strong>in</strong> <strong>the</strong> bra<strong>in</strong> (<strong>in</strong> early<br />

visual cortex) fire <strong>in</strong><br />

response to contours,<br />

whe<strong>the</strong>r <strong>the</strong>y are real or not.<br />

A: real contour<br />

B: illusory contour<br />

C: no contour<br />

Von der Heydt, Science, 1984


Illusions<br />

Illusory brightness,<br />

size, contours<br />

Halluc<strong>in</strong>ations etc.<br />

Multistable Perception<br />

B<strong>in</strong>ocular rivalry<br />

(monocular rivalry)<br />

(pattern rivalry)<br />

Ambiguous stimuli<br />

Research Paradigms<br />

for NCC and NCU<br />

ON-OFF paradigm<br />

OFF-basel<strong>in</strong>e<br />

Strong ON-OFF<br />

(perception depends on<br />

background variables)<br />

Weak ON-OFF<br />

(experimenter determ<strong>in</strong>es<br />

perception by experimental<br />

manipulation)<br />

Cont<strong>in</strong>uous flash suppression<br />

De Graaf et al (<strong>in</strong> preparation)<br />

Left or right?


What do you see?<br />

Necker cube<br />

Face/Vase<br />

Exercise


Do we see what is? : summary<br />

• Illusory contours<br />

• Context effects<br />

• Multi-stable<br />

perception<br />

What do you see?


Illusions and <strong>the</strong> like: summary<br />

• There are th<strong>in</strong>gs <strong>in</strong> our perception, that are not sensed.<br />

• The bra<strong>in</strong> constructs our percept:<br />

it does not come cleanly from <strong>the</strong> outside!!<br />

Illusions<br />

Illusory brightness,<br />

size, contours<br />

Halluc<strong>in</strong>ations etc.<br />

Multistable Perception<br />

B<strong>in</strong>ocular rivalry<br />

(monocular rivalry)<br />

(pattern rivalry)<br />

Ambiguous stimuli<br />

Research Paradigms<br />

for NCC and NCU<br />

ON-OFF paradigm<br />

OFF-basel<strong>in</strong>e<br />

Strong ON-OFF<br />

(perception depends on<br />

background variables)<br />

Weak ON-OFF<br />

(experimenter determ<strong>in</strong>es<br />

perception by experimental<br />

manipulation)<br />

Cont<strong>in</strong>uous flash suppression<br />

De Graaf et al (<strong>in</strong> preparation)


Neural Correlates of<br />

Unconsciousness<br />

• How do we know <strong>the</strong>re is such a th<strong>in</strong>g as<br />

unconscious vision?<br />

• Bra<strong>in</strong> damage (special bra<strong>in</strong>s)<br />

• Bl<strong>in</strong>dsight<br />

• Neglect<br />

Bl<strong>in</strong>dsight<br />

Presence<br />

Location<br />

Colour<br />

Orientation<br />

Direction<br />

Discrim<strong>in</strong>ation


Neural Correlates of<br />

Unconsciousness<br />

• How do we know <strong>the</strong>re is such a th<strong>in</strong>g as<br />

unconscious vision?<br />

• Bra<strong>in</strong> damage (special bra<strong>in</strong>s)<br />

• Bl<strong>in</strong>dsight<br />

• Neglect<br />

• Behavioral studies (normal(<br />

bra<strong>in</strong>s)<br />

• Mask<strong>in</strong>g-prim<strong>in</strong>g<br />

• Location<br />

• Word mean<strong>in</strong>g<br />

• Number sense<br />

NCU –neural<br />

correlates of<br />

unconsciousness<br />

• Orientation<br />

Haynes & Rees<br />

2005, nat neurosc


• Words<br />

NCU –neural<br />

correlates of<br />

unconsciousness<br />

Dehaene et al.,<br />

2001, nat neurosc<br />

NCU –neural<br />

correlates of<br />

unconsciousness<br />

• Houses>Faces<br />

Moutoussis & Zeki<br />

2002, PNAS


Stay-at<br />

at-home<br />

message<br />

• There is evidence that unconsciously<br />

perceived stimuli are processed cortically:<br />

• They result <strong>in</strong> fMRI activity<br />

• In <strong>the</strong> same bra<strong>in</strong> areas as ‘seen’stimulistimuli<br />

What is <strong>the</strong> difference between consciously<br />

see<strong>in</strong>g and unconsciously see<strong>in</strong>g???<br />

Bl<strong>in</strong>dsight<br />

• V5 activity not<br />

sufficient for conscious<br />

perception<br />

Goebel et al., Vision Res, 2001


Neural Correlates of<br />

<strong>Consciousness</strong><br />

Illusions<br />

Illusory brightness,<br />

size, contours<br />

Halluc<strong>in</strong>ations etc.<br />

Multistable Perception<br />

B<strong>in</strong>ocular rivalry<br />

(monocular rivalry)<br />

(pattern rivalry)<br />

Ambiguous stimuli<br />

Research Paradigms<br />

for NCC and NCU<br />

ON-OFF paradigm<br />

OFF-basel<strong>in</strong>e<br />

Strong ON-OFF<br />

(perception depends on<br />

background variables)<br />

Weak ON-OFF<br />

(experimenter determ<strong>in</strong>es<br />

perception by experimental<br />

manipulation)<br />

Cont<strong>in</strong>uous flash suppression<br />

De Graaf et al (<strong>in</strong> preparation)


Auditory<br />

Halluc<strong>in</strong>ations<br />

Neural Correlates of<br />

<strong>Consciousness</strong><br />

Dierks et al.,<br />

Neuron, 1999<br />

Neural Correlates of<br />

<strong>Consciousness</strong><br />

• Supernumerary phantom limb<br />

Khateb et al., 2009


Illusions<br />

Illusory brightness,<br />

size, contours<br />

Halluc<strong>in</strong>ations etc.<br />

Multistable Perception<br />

B<strong>in</strong>ocular rivalry<br />

(monocular rivalry)<br />

(pattern rivalry)<br />

Ambiguous stimuli<br />

Research Paradigms<br />

for NCC and NCU<br />

ON-OFF paradigm<br />

OFF-basel<strong>in</strong>e<br />

Strong ON-OFF<br />

(perception depends on<br />

background variables)<br />

Weak ON-OFF<br />

(experimenter determ<strong>in</strong>es<br />

perception by experimental<br />

manipulation)<br />

Cont<strong>in</strong>uous flash suppression<br />

De Graaf et al (<strong>in</strong> preparation)<br />

B<strong>in</strong>ocular Rivalry<br />

Stimulation<br />

Conscious Percept<br />

T<br />

I<br />

M<br />

E<br />

T<br />

I<br />

M<br />

E


Can you guess<br />

which graph<br />

represents BR?<br />

The o<strong>the</strong>r graph<br />

represents<br />

changes <strong>in</strong><br />

stimulation,<br />

without rivalry<br />

FFA = “face”areaarea<br />

PPA = “house”area<br />

Neural Correlates of<br />

<strong>Consciousness</strong><br />

Frontoparietal network is <strong>in</strong>volved <strong>in</strong> switch<strong>in</strong>g of conscious<br />

experience dur<strong>in</strong>g b<strong>in</strong>ocular rivalry<br />

Lumer et al., Science, 1999


Neural Correlates of<br />

<strong>Consciousness</strong><br />

Functional Connectivity:<br />

(Early) visual areas are<br />

connected to frontoparietal<br />

network to determ<strong>in</strong>e<br />

conscious experience<br />

Lumer & Rees, PNAS, 1999<br />

• Words<br />

NCU –neural<br />

correlates of<br />

(un)consciousness<br />

Dehaene et al.,<br />

2001, nat neurosc


Replicability<br />

Stay-at<br />

at-home<br />

message<br />

• When conscious percept changes, activity <strong>in</strong><br />

higher (extrastriate) visual areas changes<br />

• A frontoparietal network is <strong>in</strong>volved, when<br />

conscious percept changes<br />

• Connectivity between extrastriate areas and <strong>the</strong><br />

frontoparietal network seems important


Transcraniale magnetische stimulatie<br />

(TMS)


Magnetic tricks on consciousness<br />

• Transcranial<br />

Magnetic<br />

Stimulation (TMS(<br />

TMS)<br />

• Functional Relevance<br />

• Behavioral Effects<br />

Stay-at<br />

at-home<br />

message<br />

• TMS can manipulate <strong>the</strong> bra<strong>in</strong> (with<br />

observable effects)<br />

• Can TMS manipulate consciousness..?


Creat<strong>in</strong>g Unconsciousness<br />

123<br />

324<br />

523<br />

654<br />

ABY<br />

234<br />

543<br />

123<br />

765<br />

T<br />

I<br />

M<br />

E<br />

+/- 80 to 100 ms after a stimulus, a TMS<br />

pulse over V1 can make you unconscious<br />

Amassian et al., 1989<br />

Creat<strong>in</strong>g Bl<strong>in</strong>dsight!<br />

Mask<strong>in</strong>g a stimulus like that<br />

apparently doesn’t mean it is<br />

not processed.<br />

TMS can <strong>in</strong>duce bl<strong>in</strong>dsight!<br />

Boyer et al., 2005, PNAS


Creat<strong>in</strong>g <strong>Consciousness</strong> AND<br />

Unconsciousness<br />

Phosphenes<br />

V5: mov<strong>in</strong>g phosphenes<br />

V5 –100 ms - V1: no phoshene<br />

Pascual-Leone & Walsh, Science, 2000<br />

TMS


You <strong>in</strong> Your Body<br />

Out-of-Body<br />

Experience<br />

Blanke et al,<br />

Nature, 2002<br />

<strong>Consciousness</strong><br />

and<br />

connectivity<br />

TMS + EEG:<br />

When conscious, <strong>the</strong> effect of a<br />

TMS pulse spreads much<br />

fur<strong>the</strong>r:<br />

The bra<strong>in</strong> is ‘more connected’!<br />

Massim<strong>in</strong>i et al., Science, 2005


Stay-at<br />

at-home<br />

message<br />

• TMS CAN manipulate consciousness<br />

• Thus it CAN teach us about <strong>the</strong> locations and<br />

tim<strong>in</strong>g of conscious process<strong>in</strong>g<br />

• Early visual cortex is important around 100 ms.<br />

• Probably a k<strong>in</strong>d of feedback signal is arriv<strong>in</strong>g by<br />

that time<br />

Connectivity is key?<br />

• The <strong>in</strong>terest<strong>in</strong>g case of Neglect…<br />

• Widespread synchronization (EEG)<br />

• Work<strong>in</strong>g memory hypo<strong>the</strong>sis<br />

• Global neuronal workspace<br />

• Global availability


The future?<br />

Neural Prerequisites ?<br />

<strong>Consciousness</strong><br />

Neural Correlates<br />

Neural Consequences ?<br />

Neural Substrates ?<br />

Current neuroscience of consciousness<br />

future neuroscience of consciousness?<br />

De Graaf et al, <strong>in</strong> preparation<br />

The future?<br />

• Look for common activations across studies:<br />

• Prerequisites or consequences?<br />

• Use TMS to f<strong>in</strong>d out whe<strong>the</strong>r <strong>the</strong>se activations actually matter<br />

• Use connectivity to map <strong>in</strong>teractions between <strong>the</strong>se regions.


Research at our university<br />

Illusions<br />

Illusory brightness,<br />

size, contours<br />

Halluc<strong>in</strong>ations etc.<br />

Multistable Perception<br />

B<strong>in</strong>ocular rivalry<br />

(monocular rivalry)<br />

(pattern rivalry)<br />

Ambiguous stimuli<br />

Research Paradigms<br />

for NCC and NCU<br />

ON-OFF paradigm<br />

OFF-basel<strong>in</strong>e<br />

Strong ON-OFF<br />

(perception depends on<br />

background variables)<br />

Weak ON-OFF<br />

(experimenter determ<strong>in</strong>es<br />

perception by experimental<br />

manipulation)<br />

Cont<strong>in</strong>uous flash suppression<br />

De Graaf et al (<strong>in</strong> preparation)


Multistable Perception<br />

• People can control<br />

• What network <strong>in</strong> <strong>the</strong> bra<strong>in</strong>?<br />

• Effects of TMS on<br />

• Frontal cortex?<br />

• Parietal cortex?<br />

• On:<br />

• Passive multistable view<strong>in</strong>g?<br />

• Voluntary control of view<strong>in</strong>g?<br />

TMS & multistable control<br />

PARIETAL CORTEX<br />

FRONTAL CORTEX


150<br />

N = 8<br />

140<br />

130<br />

120<br />

110<br />

100<br />

Series1<br />

PARIETAL CORTEX<br />

90<br />

80<br />

150<br />

140<br />

130<br />

1 2 3 4 5 6 7 8 9 10 11<br />

Higher than 100%<br />

means<br />

DECREASE <strong>in</strong><br />

voluntary control<br />

120<br />

110<br />

100<br />

Series1<br />

FRONTAL CORTEX<br />

90<br />

80<br />

1 2 3 4 5 6 7 8 9 10 11<br />

time<br />

De Graaf et al., <strong>in</strong> progress<br />

Information Flow <strong>in</strong> <strong>the</strong> Bra<strong>in</strong><br />

A B C<br />

effective<br />

connectivity<br />

activity<br />

time<br />

A<br />

C<br />

B<br />

A<br />

A<br />

De Graaf et al., 2009, JOCN


Illusions<br />

Illusory brightness,<br />

size, contours<br />

Halluc<strong>in</strong>ations etc.<br />

Multistable Perception<br />

B<strong>in</strong>ocular rivalry<br />

(monocular rivalry)<br />

(pattern rivalry)<br />

Ambiguous stimuli<br />

Research Paradigms<br />

for NCC and NCU<br />

ON-OFF paradigm<br />

OFF-basel<strong>in</strong>e<br />

Strong ON-OFF<br />

(perception depends on<br />

background variables)<br />

Weak ON-OFF<br />

(experimenter determ<strong>in</strong>es<br />

perception by experimental<br />

manipulation)<br />

Cont<strong>in</strong>uous flash suppression<br />

De Graaf et al (<strong>in</strong> preparation)<br />

• Controlled by<br />

TMS:<br />

TMS-<strong>in</strong>duced<br />

bl<strong>in</strong>dsight<br />

ON-OFF<br />

OFF-basel<strong>in</strong>e<br />

120<br />

100<br />

80<br />

60<br />

40<br />

20<br />

0<br />

20 ms<br />

Orientation<br />

ep mp lp cp<br />

time w<strong>in</strong>dow<br />

*<br />

100 ms<br />

seen %<br />

unseen & correct %<br />

AND<br />

non-bl<strong>in</strong>dsight<br />

bl<strong>in</strong>dsight!<br />

120<br />

100<br />

80<br />

*<br />

Color<br />

*<br />

60<br />

seen %<br />

unseen & correct %<br />

40<br />

20<br />

0<br />

ep mp lp cp<br />

20 ms<br />

time w<strong>in</strong>dow<br />

100 ms


M<strong>in</strong>d Read<strong>in</strong>g<br />

Questions…<br />

Thanks to:<br />

Ra<strong>in</strong>er Goebel<br />

Alexander Sack<br />

Christianne Jacobs

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