specchi nel cervello

ETICA E GENETICA
Milano - Giovedì 26 Febbraio 2009
SPECCHI NEL CERVELLO
Corrado Sinigaglia
University of Milan Department of Philosophy
Via Festa del Perdono 7
20122 Milano (Italy)
E-mail:[email protected] Web: www.filosofia.unimi.it/infosinigaglia/
What is directly matched is the motor aboutness that characterizes both the
effective observed and the effective executed motor acts. The fact that the
observation of a motor act performed by others generates a motor
activation similar to that would underpin the execution of that motor act by
the observer suggest that effective
and effective
executed
motor
Theobserved
DM hypothesis
maintains
that the
acts share the same motor aboutness
and thatofthe
the identity
observation
an status
action and
performed
by of
a given motor act,, whether observed
or performed,
depends primarily
others evokes,
in the observer’s
brain, a
on this motor
is alike to that
motor aboutness.
activation that
which occurs during the planning and
effective execution of that action. The directness of matching not only does not involve that it uniquely runs
Thealso
difference
is that
while
the latter
at the low (kinematics)-level , but
does not
imply
that in
it has
to be
motor activation
becomes an
construed in termscase
of athe
one-to-one
mapping.
overt motor act, in the former it remains
at the stage of a potential motor act,
thussensory
enabling
the observer
to be able to
Without such mapping, at best the
information
would
understand
the observed
provide us with a description immediately
of various features
of observed
bodily
movements, but it would not be motor
able toact
pick up their intentional meaning,
i.e. what these movements are about. A. 1 Ventral PM 2 Dorsal PM 3 IPS 4 pSTS
B. 1 SPL 2 IPS
I found it hard work to move at all, as I had to think out
everything I did in order to be able to do it. In a way, I had
to order my body to carry out what it had to do by
thinking it out all the time. Gunilla Gerland, A real person, p.12
BOTH OF US DISGUSTED IN MY INSULA
Electrophysiological evidence
Philipps et al. 1997 found that the intensity of activation
of insular cortex is proportional to the observed disgust.
Krolak Salmon et al. 2003 recorded evoked potentials
from the insula of epileptic patients, observing that the
anterior region of the insula responded selectively to
the sight of disgusted faces
Clinical studies
The anterior region of insula is closely
connected with gustatory and olfactory
centers; it also receives information
from the ventral part of STS (face
sensitive); finally, it is a viscero-motor
integration center: when it is electrically
stimulated, it causes bodily movements
accompanied by visceral effects such
as an increase in heart beat, dilation of
pupil, retching, and so on.
Calder et al. 2000 reported the case of a patient (NK)
who, following a cerebral haemorrhage, had a severe
damage in the left insula. Polymodal (visual, acoustic)
and selective (disgust, but not fear or anger) deficit
correlated with her inability to feel disgust.
Adolphs et al 2003 reported the case of a patient (B)
with a bilateral lesion of the insula. He was no longer
able to identify both facial grimaces and noisy
expressions of disgust. In addition, he was no longer
able to experience disgust, swallowing things that are
totally inedible and absolutely disgusting. BOTH OF US DISGUSTED IN MY INSULA
In the visual session,
only the sight of
disgusted grimaces
activated the anterior
part of L insula (as well
as the anterior part of
R cingulate cortex).
Conversely, there was
no activation in
amygdala.
Olfactory session
A. Coronal sections showing the activations of
amygdala produced by both pleasant and
disgusting smells
B. Axial slice showing that the disgusting
smells activated the anterior region of R and L
insula, while the pleasant odors activated a
more posterior site of L insula.
PAIN-RELATED NEURONS IN HUMAN CINGULATE CORTEX
This single neuron
recording study in
neurological patients
showed that there are
pain related neurons in
the anterior cingulate
cortex (ACC) that
respond both to the
actual stimulation and
also to the same stimuli
delivered to another
individual.
Hutchinson et al.
1999
Similar results were obtained by Morrison et al. 2004. In this fMRI study participants underwent
stimulation of one hand by a needle-like sharp probe, and, in another condition, they watched
videos of someone else’s hand being pricked by a hypodermic needle. Results reveal common
activated foci in ACC and in AIC In a second experiment participants
observed a needle penetrating a
foot and a Q-tip touching the same
region, while in third experiment
they observed a needle penetrating
in ADM and in a foot. The results
were in line with those obtained in
the first experiments.
First experiment. Motor evoked potentials (MEPs) to
focal TMS of the left motor cortex were recorded
simultaneously from two muscles of observer’s right
hand, i.e. the first dorsal interosseous (FDI) and the
abductor digiti minimi (ADM). Different categories of
visual stimuli: A needle penetrating the FDI muscle; a
Q-tip gently moving and pressing on FDI; a needle
penetrating a tomato. MEPs amplitude recorded from
FDI were significantly lower in the Needle in FDI
condition than in the other ones. This indicates a
decrease of motor excitability during the observation of
other’s pain. THE SOMATOSENSORY SIDE OF PAIN EXPERIENCE
The
experience
of pain relies
not only on
an affectivemotivational
simulation,
but also on a
fine-grained
somatic
simulation
The analysis of the subjective judgments (measured by sensory and affective subscales of the McGill Pain
Questionnaire and two Visual Analogous Scales related to pain intensity and unpleasantness) about the different
components of pain experience ascribed to the model during needle penetration showed that amplitude
changes of MEPs were negative correlated with sensory ratings but not with affective scores.
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