Consciousness in the Human Brain - Maastricht University
Consciousness in the Human Brain - Maastricht University
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