NEUROREPORT

MOTOR SYSTEMS

Feeling touches in someone else’s hand
Gabriella Bottini,1,2,CA Edoardo Bisiach,3 Roberto Sterzi 4 and Giuseppe Vallar5
1

Psychology Section, Department of Philosophy, University of Pavia, Piazza Botta 6, 27100 Pavia; 2Neuropsychology Laboratory,
Department of Neurological Sciences, Ospedale Niguarda Ca' Granda, Milan; 3Psychology Department, University of Turin,
Turin; 4Neurology Department, Sant’Anna Hospital, Como and 5Psychology Department, University of Milano-Bicocca,
Milan, Italy
CA,1

Corresponding Author and Address

Received 25 November 2001; accepted 7 December 2001

Cerebral damage may induce a delusional belief so that patients
claim that their limbs contralateral to the side of the lesion belong
to someone else (somatoparaphrenia). This disorder, which is not
due to a general delirium, is frequently accompanied by the inability
to feel tactile sensations in the‘non-belonging’ part of the body.We
report the unique case of a patient with somatoparaphrenia in
whom dense tactile imperception in the left hand dramatically recovered when she was instructed to report touches delivered to

her niece’s hand, rather than to her own hand. We suggest that,
through this verbal instruction, the mismatch between the patient’s belief about the ownership of her left hand and her ability
to perceive touch on it was transiently recomposed. This is evidence that apparently elementary de¢cits, such as hemianesthesia,
and selective delusional behavior, such as somatoparaphrenia, may
both originate from an impairment of the body image. NeuroReport
13:249^252 c 2002 Lippincott Williams & Wilkins.

Key words: Body image; Ownership; Somatoparaphrenia; Spatial neglect

INTRODUCTION

CASE REPORTAND METHODS

How do we know that our limbs are our own, and do not
belong to someone else? Is there any relationship between
this sense of ownership of body parts and our awareness of
the sensory quality of our body? Under conditions of
normal brain function, touches delivered, for instance, to
our hands are reported as stimuli given to a part of our
body. However, brain damage may disrupt tactile perception and, though less frequently, sense of ownership. This
pathological state offers the unique opportunity of investigating the role of sense of body ownership in somatosensory
awareness. The neuroanatomical functional organization of
the brain is such that the inability to report touches
delivered to one side of the body (hemianesthesia) is
brought about by a lesion to the contralateral somatosensory
parietal cortex [1–3]. In humans, when damage to the right
hemisphere occurs, left hemianesthesia may sometimes be
accompanied by a higher-order impairment of body awareness which, as tactile imperception, concerns the contralateral left side of the body. Patients may exhibit a delusional
belief concerning the sense of ownership of body parts,
claiming that their left limbs belong to someone else
(somatoparaphrenia) [4].
We explored the putative relationship between tactile
imperception in particular body parts and selective delusional behavior concerning those body parts in a right brain
damaged woman who showed both hemianesthesia and
somatoparaphrenia.

F.B. was a 77-year-old right-handed woman who, on the
17th December 1999, sustained a stroke in the right cerebral
hemisphere. A CT scan showed a right subcortical hemorrhage (Fig. 1). This lesion caused left-sided neurological
deficits: hemiplegia, hemianaesthesia, and hemianopia.
Gross spatial unilateral neglect for the left side of space
[5,6] was found during the copy of various figures and on a
number of tasks. On the line bisection test F.B. was asked to
mark with a pencil the center of a 20 cm horizontal line,
printed on an A4 page, centered on the mid-sagittal plane of
her body. The patient made a dramatic rightward error,
setting the subjective mid-point on the right end of the line
(Fig. 2a). On Albert’s cancellation test F.B. was asked to cross
out 40 short lines printed on an A4 sheet. F.B. crossed out
only six lines on the extreme right side of the sheet,
spontaneously adding material, as right brain damaged
patients sometimes do [7] (Fig. 2b).
As may occur in unilateral neglect, the patient firmly
denied her left neurological deficits (anosognosia). Patients
with unilateral neglect are not only unable to attend to
stimuli in the extra-personal, contralesional space, but
may also show difficulties in attending to and exploring
the left side of their own body [8]. F.B. did not report
any touch given to her left hand. When she was required to
touch her left hand she was not able to reach it: she confined
her search to the right side of her peri-personal space,
randomly exploring for her left hand. The patient also

0959- 4965 c Lippincott Williams & Wilkins

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NEUROREPORT

G. BOTTINI ETAL.

Fig. 1. Patient F.B.’s CT Scan of the right hemisphere lesion. The haemorrhage invades, from bottom to top, the putamen and pallidum, the posterior
brachium of the internal capsule, the white matter underlying the cortex of the following strunctures: insula, superior temporal gyrus, parietal operculum, pre- and post-central gyri. R = right.

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NEUROREPORT

SOMATOPARAPHRENIA AND BODY IMAGE

Table 1. Patient F.B.’s report of touches given to her left or right hand.
Side of tactile stimulation

Responses

(% correct)

Yes

No

24.12.1999/1
Right hand
Left hand
Left hand (niece’s hand)
Catch trials

10
0
7
0

0
10
3
9

(100%)
(0%)
(70%)
(100%)

24.12.1999/2
Right hand
Left hand
Left hand (niece’s hand)
Catch trials

10
0
7
0

0
10
3
9

(100%)
(0%)
(70%)
(100%)

25.12.1999/1
Right hand
Left hand
Left hand (niece’s hand)
Catch trials

10
0
10
0

0
10
0
9

(100%)
(0%)
(100%)
(100%)

25.12.1999/2
Right hand
Left hand
Left hand (niece’s hand)
Catch trials

10
0
8
0

0
10
2
9

(100%)
(0%)
(80%)
(100%)

RESULTS
Fig. 2. Patient F.B.’s performance in (a) line bisection and (b) Albert’s
cancellation task [15]. Note on the right side of the sheet a drawing spontaneously made by F.B. while performing the cancellation task.

manifested a delusional behavior confined to her left hand,
which she claimed to belong to her niece. Somatoparaphrenia, which may sometimes be associated with left
unilateral neglect, was invariably observed over different
days and became chronic along with the left hemianaesthesia, still being present 2 months after the acute cerebral
accident. F.B. was nevertheless fully oriented in time and
space and did not show any other sign of mental
deterioration on the Mini Mental State Examination (score:
26/31) [9].
Following a preliminary assessment confirming F.B.’s
complete inability to report touches delivered to her left
hand, we explored the relationship between her tactile
imperception and her selective delusion, using different
verbal warnings. On each trial the examiner briefly touched
the dorsal surface of F.B.’s hand with the index finger, and
warned her that he/she was going to touch (a) her right
hand, (b) her left hand, (c) her niece’s hand. In the latter
condition (c), the examiner touched F.B.’s left hand. The
patient was blindfolded and instructed to say ‘yes’ when
she felt a touch and ‘no’ when she did not feel any touch.
Touches were delivered in a randomised fixed order. Catch
trials, evenly distributed across the three verbal conditions,
were introduced in order to monitor F.B.’s level of sustained
attention and reliability of response. F.B.’s tactile perception
was assessed in four sessions performed on two consecutive
days.

When F.B. was required to report touches delivered to her
niece’s hand, her tactile imperception dramatically
recovered (Table 1). Immediately after the experiment, we
asked F.B. how she could report touches on someone
else’s hand. Her response was initially elusive; however
she eventually explained the phenomenon as follows
(though adding ‘Yes, I know, it is strange’): her
absent-minded niece would always forget her hand
on the patient’s bed while leaving the hospital, so that F.B.
used to take care of it until the niece came back to visit her
again.

DISCUSSION
Patient F.B.’s behavior sheds light on important aspects of a
much debated issue in cognitive neuroscience [10]: the
nature of the belief of ownership of body parts and its
disorders. Body segments are mapped in an orderly fashion
onto somatosensory and motor cortices. Their representations are resistant to the absence of the corresponding
physical objects as illustrated by the vivid persistent
perception of an amputated body part in the phantom limb
syndrome [11,12]. Somatoparaphrenia may be considered
the opposite phenomenon: a limb, although still part of the
body, is felt as if it were not belonging to the body itself.
F.B.’s spared ability to perceive tactile stimuli, provided
that these were referred to someone else’s body, was
evidently based on the survival of some elementary
somatosensory cortical functions, perhaps of the kind
mapped in primary or secondary somatosensory cortices
[1,2]. The behavior of our patient, however, shows that these
sensory representations are not sufficient to generate the
sense of ownership of the touched limb. F.B.’s recovered

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NEUROREPORT
ability to report touches on the affected left upper limb,
following verbal instructions coherent with her delusion, is,
under some respects, similar to the phenomenon of
allochiria [13] which, like somatoparaphrenia, may be
associated with the syndrome of spatial unilateral neglect.
Patients with tactile allochiria perceive touches contralateral
to the side of the lesion, but refer them to the ipsilateral side
of their body [14]. Patient F.B. reported left-sided touches
only when, prompted by the examiner, she delusively
referred them to someone else’s body image. In both
conditions, conscious tactile perception would occur only
when the disrupted representation of one side of the body is
replaced by a preserved image: that of the unaffected side in
allochiria, or, as in patient F.B., the delusional image of a
body part of another person.
The transient remission of F.B.’s tactile deficit via an
interplay with her somatoparaphrenic delusion demonstrates that somatosensory awareness involves a crucial
contribution from a higher-level representation of the body,
including basic beliefs, such as ownership.

CONCLUSION
The nature of the belief of ownership of body parts is a
major issue in cognitive neuroscience of consciousness.
Limb representation can survive to the absence of the
corresponding physical objects, as in the phantom limb
syndrome. In a different syndrome, somatoparaphrenia, one
can observe the opposite phenomenon: a limb, although still
part of the body, is felt as if it were not belonging to the body
itself rather it is vividly felt as belonging to someone else.
Somatoparaphrenia is frequently associated with hemianaesthesia and unilateral neglect.
In this paper we describe the unique case of a patient with
somatoparaphrenia and phenomenological hemianeasthesia
who was very accurate in reporting tactile stimuli when
these were delivered to what she believed to be someone

G. BOTTINI ETAL.

else’s hand. Our experiment provides evidence that elementary somatosensory representations are not sufficient to
give rise to a sense of ownership, rather both, elementary
tactile perception and sense of ownership; rather, both
elementry tactile perception and sense of ownership must
depend on a more abstract/higher level body image.

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Acknowledgements: The present investigation was inspired by an informal clinical observation reported to E.B. by Professor
M.W. van Hof, of the Erasmus Universiteit Rotterdam.This study was supported in part by grants of Bracco spato G.B. and MURST
grants to E.B. and G.V.We are grateful to Eraldo Paulesu for his comments on an earlier version of the manuscript.

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