Somatotopy of the Anterior Cingulate Cortex and Supplementary Motor Area for tactile stimulation of

1
12TH ANNUAL MEETING OF THE ORGANIZATION FOR HUMAN
BRAIN MAPPING, JUNE 11-15, 2006 - FLORENCE, ITALY
Somatotopy of the Anterior Cingulate Cortex and
Supplementary Motor Area for tactile stimulation
of the hand and the foot
D. Arienzo1,2, T.D. Wager3, J. Ferrera4, G.L.
Romani1,2, J. Hirsch4, 1 Department of Clinical
Sciences and Bioimaging, G. D'Annunzio
University, Chieti, Italy 2 Institute for
Advanced Biomedical Technologies, G. D'Annunzio
University Foundation, Chieti, Italy 3
Department of Psychology, Columbia University,
New York, USA 4 Department of Radiology, fMRI
Center, Columbia University, New York, USA.
497 TH - AM
INTRODUCTION
HAND
FOOT
Although the somatotopic organization of early
sensory and motorsensitive areas is well
established, the somatotopic organization of
supplementary and executive regions is an active
investigational question. Positron emission
tomography (PET) has shown a within-arm
somatotopy in ACC and SMA during visuomotor
tracking tasks involving the shoulder, the elbow,
the wrist, the finger, the thumb and the eye 1.
More recent fMRI evidence has indicated an
activation of the ACC and SMA following
nonpainful electrical stimulation of the hand and
foot 2. The present study aims at evaluating
the working hypothesis that the spatial
segregation of somatosensory inputs in
cognitive-sensorimotor areas such as ACC and SMA
is present with tactile stimulation of the hand
and foot.
ACC
METHODS
Figure 1. Results of a typical subject showing
the activated areas in the anterior cingulate
cortex (ACC) after tactile stimulation to the
hand and the foot. Red activated areas during
hand stimulation. Blue activated areas during
foot stimulation.
Subjects and
Stimuli Ten right handed healthy volunteers (19
to 33 years, 5 males, 5 females). Tactile
stimulation delivered to either the right hand or
the right foot. Data acquisition and
analysis BOLD functional imaging was performed
with a 1.5T G.E. scanner by means of T2 EPI
sequences (TR 2s, TE 52 ms, matrix 64x64, voxel
size 4 mm x 4 mm, flip angle 90, slice thickness
4.5 mm). Functional volumes consisted of 21
slices acquired parallel to the AC-PC line. Each
scanning session was composed of two parts a
block design paradigm and an event related design
paradigm. The block design paradigm consisted of
3 runs, each presenting an alternating sequence
of 13 16s-long blocks of either rest or paint
brush stimulation to the hand or the foot. Each
run lasted 3 minutes and 34 seconds and, at a
TR2s, yielded 107 volumes. In the event related
design there were 8 runs, each consisting of 24
trials, 12 of which lasted 11 s, and 12 lasted 15
s. Each run lasted 5 minutes and 22 seconds and,
at TR2, yielded 161 volumes. Data were analyzed
in the general linear model framework with Brain
Voyager 4.9. Preprocessed functional images were
transformed into the Talairach space. Talairach
coordinates of activation were selected at the
most significant voxel in each cluster. The
difference in the individual Talairach
coordinates between median and tibial nerve
activation was tested for ACC and SMA with an
ANOVA test.
HAND
FOOT
SMA
 
Figure 2. Results of a typical subject showing
the activated areas in the supplementary motor
area (SMA) after tactile stimulation to the hand
and the foot. Red activated areas during hand
stimulation. Blue activated areas during foot
stimulation.
DISCUSSION
We used functional magnetic resonance imaging
(fMRI) to test the hypothesis of a somatotopic
organization in the anterior cingulate cortex
(ACC) and in the supplementary motor area (SMA)
for tactile stimulation to the hand and the foot.
Individual functional maps showed a clear
segregation of activation in the two different
paradigms. The preliminary results of the present
study support the working hypothesis of a spatial
segregation of somatosensory inputs in
cognitive-sensorimotor areas such as ACC and SMA.
RESULTS
The results demonstrated somatotopic
organization of hand and foot within both the ACC
and the SMA for both the event related design
paradigm and for the block design paradigm .
Results from a typical subject are depicted in
Figures 1 and 2. These preliminary results
confirm the working hypothesis supporting the
importance of spatial segregation of
somatosensory inputs in cognitive-sensorimotor
areas such as ACC and SMA .
REFERENCES
1Grafton ST et al. Exp Brain Res. 199395172.
2 Ruben J. et al. Cereb Cortex. 200111463.